A20-OLinuXino-MICRO
Open-source single-board
Android/Linux mini-computer

USER’S MANUAL
Document revision S, March 2018
Designed by OLIMEX Ltd, 2015

All boards produced by Olimex LTD are ROHS compliant

OLIMEX© 2018

A20-OLinuXino-MICRO user's manual

DISCLAIMER© 2018 Olimex Ltd. Olimex®, logo and combinations thereof, are registered trademarks of Olimex Ltd. Other productnames may be trademarks of others and the rights belong to their respective owners.
The information in this document is provided in connection with Olimex products. No license, express or impliedor otherwise, to any intellectual property right is granted by this document or in connection with the sale of
Olimex products.
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License. To view a copy ofthis license, visit http://www.creativecommons.org/licenses/by-sa/3.0/.

This hardware design by Olimex LTD is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported
License.
The software is released under GPL.
It is possible that the pictures in this manual differ from the latest revision of the board.
The product described in this document is subject to continuous development and improvements. All particulars of the
product and its use contained in this document are given by OLIMEX in good faith. However all warranties implied or
expressed including but not limited to implied warranties of merchantability or fitness for purpose are excluded. This
document is intended only to assist the reader in the use of the product. OLIMEX Ltd. shall not be liable for any loss ordamage arising from the use of any information in this document or any error or omission in such information or any
incorrect use of the product.
This evaluation board/kit is intended for use for engineering development, demonstration, or evaluation purposes only
and is not considered by OLIMEX to be a finished end-product fit for general consumer use. Persons handling the
product must have electronics training and observe good engineering practice standards. As such, the goods being
provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related
protective considerations, including product safety and environmental measures typically found in end products thatincorporate such semiconductor components or circuit boards.
Olimex currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive. Olimex assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein.

THERE IS NO WARRANTY FOR THE DESIGN MATERIALS AND THE COMPONENTS
USED TO CREATE A20-OLINUXINO-MICRO. THEY ARE CONSIDERED SUITABLE
ONLY FOR A20-OLINUXINO-MICRO.

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Table of Contents
DISCLAIMER............................................................................................................. 2
CHAPTER 1: OVERVIEW........................................................................................5
1. Introduction to the chapter.......................................................................................................5
1.1 Features.....................................................................................................................................5
1.2 Target market and purpose of the board...............................................................................6
1.3 Board variants..........................................................................................................................6
1.4 Board version used in the manual..........................................................................................7
1.5 Organization.............................................................................................................................7

CHAPTER 2: SETTING UP THE OLINUXINO BOARD.....................................8
2. Introduction to the chapter.......................................................................................................8
2.1 Electrostatic and electrical polarity warning........................................................................ 8
2.2 Requirements........................................................................................................................... 8
2.3 Powering the board................................................................................................................10
2.4 Prebuilt software.................................................................................................................... 11
2.5 Button functions..................................................................................................................... 11
2.6 Interacting with the board....................................................................................................122.6.1 HDMI monitor..............................................................................................................................................122.6.2 VGA monitor.................................................................................................................................................13
2.6.3 SSH via mini USB cable in Debian.............................................................................................................13
2.6.4 SSH via Ethernet..........................................................................................................................................13
2.6.5 LCD display..................................................................................................................................................13

2.7 Changing the default image resolution................................................................................14
2.8 Connecting a display and calibrating touchscreen.............................................................16
2.8.1 Android toucshcreen calibration.................................................................................................................162.8.2 Debian touchscreen calibration...................................................................................................................16

2.9 GPIO under Debian...............................................................................................................17
2.10 I2C and SPI under Debian..................................................................................................18
2.11 Software support..................................................................................................................18

CHAPTER 3: A20-OLINUXINO-MICRO BOARD DESCRIPTION.................19
3. Introduction to the chapter.....................................................................................................19
3.1 Layout (top view)...................................................................................................................19
3.2 Layout (bottom view).............................................................................................................20

CHAPTER 4: THE ALLWINNER A20 EMBEDDED PROCESSOR.................21
4. Introduction to the chapter.....................................................................................................21
4.1 The processor......................................................................................................................... 21
4.2 Block diagram........................................................................................................................ 22

CHAPTER 5: CONTROL CIRCUITY................................................................... 23
5. Introduction to the chapter.....................................................................................................23
5.1 Reset........................................................................................................................................23
5.2 Clocks......................................................................................................................................23
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5.3 Power supply circuit.............................................................................................................. 23

CHAPTER 6: CONNECTORS AND PINOUT......................................................24
6. Introduction to the chapter.....................................................................................................24
6.1 Communication with the A20............................................................................................... 24
6.1.1 USB-OTG communication (NAND firmware repair/update)..................................................................24
6.1.2 UART0, UEXT1, UEXT2 interface............................................................................................................26

6.2 SD card connectors................................................................................................................27
6.2.1 SD/MMC1 slot..............................................................................................................................................28
6.2.2 SD/MMC slot................................................................................................................................................29

6.3 PWR jack................................................................................................................................30
6.4 MIC_IN & HEADPHONES connectors..............................................................................30
6.5 USB_OTG connector.............................................................................................................31
6.6 USB_HOST connector...........................................................................................................33
6.7 Ethernet.................................................................................................................................. 34
6.8 HDMI connector.................................................................................................................... 36
6.9 VGA connector.......................................................................................................................37
6.10 SATA connector and power.................................................................................................38
6.11 GPIO ports............................................................................................................................39
6.11.1 GPIO-1 (General Purpose Input/Output) 40pin connector**................................................................39
6.11.2 GPIO-2 (General Purpose Input/Output) 40pin connector....................................................................40
6.11.3 GPIO-3 (General Purpose Input/Output) 40pin connector....................................................................41

6.12 LCD_CON 40pin connector................................................................................................43
6.13 Jumper description..............................................................................................................44
6.14 Additional hardware components...................................................................................... 45

CHAPTER 7: SCHEMATICS..................................................................................46
7. Introduction to the chapter.....................................................................................................46
7.1 Eagle schematic......................................................................................................................46
7.2 Physical dimensions...............................................................................................................47

CHAPTER 8: REVISION HISTORY AND SUPPORT........................................ 48
8. Introduction to the chapter.....................................................................................................48
8.1 Document revision................................................................................................................. 48
8.2 Board revision........................................................................................................................ 50
8.3 Useful web links and purchase codes...................................................................................52
8.4 Frequently asked questions (FAQ).......................................................................................53
8.5 Product support..................................................................................................................... 56

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CHAPTER 1: OVERVIEW
1. Introduction to the chapter
Thank you for choosing this A20 single board computer from Olimex! This document provides auser’s guide for the Olimex A20-OLinuXino-MICRO board. As an overview, this chapter gives thescope of this document and lists the board’s features. The document’s organization is then detailed.
The A20-OLinuXino-MICRO development board allows evaluation of the A20 processor,
manufactured by Allwinner Technology from China. The board is suitable for research anddevelopment, but it can also be embedded in own products.
OLinuXino is an open-source, open-hardware project and all documentation that we used to
manufacture the board is available to the customer.

1.1 Features
The board has the following set of features (please note the difference between the two versions of
the board):
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A20 Cortex-A7 dual-core ARM Cortex-A7 CPU and dual-core Mali 400 GPU
1GB DDR3 RAM memory
4GB or 8GB NAND FLASH memory (available only on certain variants of the board)
4GB eMMC memory (available only on certain variants of the board)
Industrial temperature range versions available (boards with “-IND” suffix)
SATA connector with 5V SATA power jackCapable of FullHD (1080p) video playback
Native HDMI output with connector; VGA output on 6-pin 1.25mm (0.05'') step connector
2 x USB High-speed host with power control and current limiter
USB-OTG with power control and current limiter
100MBit native Ethernet
Battery connector with battery-charging capabilities
Audio headphones output on connector
Microphone input on connector
2 x UEXT connectors
LCD connector compatible with with 4.3'', 7.0'', 10.1" LCD displays from Olimex
160 GPIOs on three GPIO connectors
MicroSD card connector
SD/MMC card connector
DEBUG-UART connector for console debug with USB-SERIAL-CABLE-F
Battery charge status LED and GPIO LED
2KB EEPROM for MAC address storage and more
10 BUTTONS with ANDROID functionality + RESET button
4 mount holes
Power jack for external power supply (7-24)V DC1
PCB dimensions: (5600×3250) mils ~ (142.24×82.55) mm

For boards revision J or newer; the voltage applied to the power jack should be (6-16)V for older board revisions
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1.2 Target market and purpose of the board
The boards from the OLinuXino family are easy to setup and powerful. It is possible to use them inalmost any application as a host board. They are suitable for embedded programming enthusiasts,
Linux and Android gadget fans (they can just use the board as a media center or fully functionalLinux-PC, for instance) and also professionals (since its low cost makes it very good solution for
application-orientated embedded systems). The main usage of the board is software embedded
development without the urge of understanding perfectly the hardware.
The strong points of the boards are the processor speed, the small form factor and the low price-toproductivity ratio. The presence of native SATA and Ethernet controller and built-in battery charger
circuit allows the development of a wider range of products, compared to typical embedded Linuxboards. The A20-OLinuXino-MICRO is a mature product – a lot of experience and projects are
already available such as GPIO, UART, I2C, SPI, CAN libraries and examples. The A20 chip is also
very well known and well supported (including in mainline u-boot and kernel).
Customers have full access to the technical documentation of the board. The software is released
under General Purpose License and the board is considered open-hardware – all schematics andboard design files are available to the customer under the Creative Commons AttributionShareAlike 3.0 Unported License.

1.3 Board variants
The board has six board variants. The base version of the board, that comes with NO extra flash
memory, and works in the commercial temperature range is named A20-OLinuXino-MICRO. Thebase version is usually sufficient for research and development (unless your project specificallyrequires industrial temperature range and extra flash memory storage).
You might find a comparison table of the different board variants below:
Board variant

Extra
flash

Type offlash

Size offlash

Boot Linux from flash
memoryOperatingtemperature
range

A20-OLinuXino-MICRO

No

-

-

-

0°C – 70°C

A20-OLinuXino-MICRO-IND

No

-

-

-

-40°C – 85°C

A20-OLinuXino-MICRO-e4GB

Yes

eMMC

4GB

Yes, after install script

0°C – 70°C

A20-OLinuXino-MICRO-e4GB-IND

Yes

eMMC

4GB

Yes, after install script-40°C – 85°C

A20-OLinuXino-MICRO-n4GB

Yes

NAND

4GB

Yes, after install script

0°C – 70°C

A20-OLinuXino-MICRO-n8GB

Yes

NAND

8GB

Yes, after install script

0°C – 70°C

The different versions of the boards can be determined by the suffixes after the base A20OLinuXino-MICRO name, different names determine different version. The suffixes indicate three
things:i) type of flash (“e” stands for eMMC; “n” stands for “NAND”; if there is flash memory at all)ii) size of flash (“4GB” or “8GB”)iii) whether the board uses industrial temperature grade components (when “IND” suffix is present)
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The prices for different board versions are also different. These four versions with extra flash
memory are named: A20-OLinuXino-MICRO-e4GB, A20-OLinuXino-MICRO-e4GB-IND,
A20-OLinuXino-MICRO-n4GB, and A20-OLinuXino-MICRO-n8GB. The name consists of thetype of the memory and the size of the memory – suffix “e4GB” stands for eMMC type of flash
with 4GB of size; “n4GB” stands for NAND type of flash with 4GB of size; “IND” stands for aboard with industrial temperature range components.
The other Olimex boards with close characteristics are the ones with A13 and A10 microcontrollers.
The A13 boards feature a generation older processor but since they have been longer on the market
they might have better Linux and Android support. The A10 boards feature single (than A20)
processor core but they are more energy efficient making them better choices for handheld devices
and devices requiring power efficiency. A more powerful chip than the A20 is used in the design of
A64-OLinuXino.
For projects and designs that require smaller form factor good alternatives to A20-OLinuXinoMICRO are: A20-OLinuXino-LIME2, A20-OLinuXino-LIME, A20-SOM-EVB, A20-SOM204EVB. For more powerful and recent designs consider the A64-OLinuXino board.

1.4 Board version used in the manual
Board from revision J was used while writing this document. It is possible that they are outdated so
it is always recommended to download the latest sources from the GitHub page of the board.

1.5 Organization
Each section in this document covers a separate topic, organized as follows:
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Chapter 1 is an overview of the board usage and features
Chapter 2 provides a guide for quickly setting up the board and software notes
Chapter 3 contains the general board diagram and layout
Chapter 4 describes the component that is the heart of the board: the A20 – Allwinnerprocessor
Chapter 5 is an explanation of the control circuitry associated with the microcontroller
Chapter 6 covers the connector pinout, peripherals and jumper description
Chapter 7 provides the schematics and the dimensions of the board
Chapter 8 contains the revision history, useful links and support information

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CHAPTER 2: SETTING UP THE OLINUXINO BOARD
2. Introduction to the chapter
This section helps you set up the OLinuXino development board for the first time. Please consider
first the electrostatic warning to avoid damaging the board, then discover the hardware and software
required to operate the board.
The procedure to power up the board is given, and a description of the default board behavior isdetailed.

2.1 Electrostatic and electrical polarity warningThis product is shipped in a protective anti-static package. The board must not be exposed to highelectrostatic potentials. A grounding strap or similar protective device should be worn whenhandling the board. Avoid touching the component pins or any other metallic element.
Ensure that your development board gets attached to properly working hardware. For example, it iscommon for cheap HDMI monitors to lack grounding. Avoid TVs which have no grounding on theirpower supply cable! If you can’t avoid them try to add the grounding yourself, if this is not possible
please use insulation products like USB-ISO to save your development board from potential overvoltage.
If you connect other electrical devices to the A20 board make sure that they have equal electricalpolarity. For example, when you connect an HDMI cable between a TV and the board it is a goodidea to have them both connected to the same electrical source (to the same utility power socket).
This might be said for a serial cable connected between a PC and the board's DEBUG port.
In rare cases different polarity might cause hardware damage to the board.

2.2 Requirements
In order to set up the A20-OLinuXino-MICRO optimally one or more additional items may be used.
They might be generally placed in three categories:
Required – items that are needed in order to achieve minimum functionality;
Recommended – items that is good to have in order to be able to interact with the most importantof the features of the board;
Additional – items that provide access to additional features or expand the features of the board.
Required items:- USB type A to USB mini cable – to connect to a personal computer; used for powering the board
and uploading new Android image to the NAND memory (if your board has 4GB NAND)- Input device – either a mouse/keyboard or touchscreen LCD- Output device – either HDMI cable + native HDMI monitor/screen/projector; or USB-SERIALCABLE-F + personal computer (for Linux and/or Android debugging); or OLIMEX LCD (TS)display + 40-pin CABLE-IDC40-15cm; or A20-VGA-CABLE + VGA monitor/screen/projector- SD card with compatible image – if you have the board version with NO additional NAND
memory you will need it to use one of the images available.
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Recommended items:- External USB hub – to split the USB_HOST mounted on the board; you need that to connect more
USB devices- External power supply unit – (7-24)V DC2, 5W(10V @ 0.5A) required – for optimal power;- USB-SERIAL-CABLE-F – for Android/Linux debugging on UART0- CABLE-IDC40-15cm – cable used for LCD_CON ↔ Olimex LCD display- Adapter cable for the 6-pin VGA connector to standard VGA 15-pin connector
Additional items include:- Audio device for HEADPHONES jack
- Ethernet cable for wired Ethernet- A number of extension modules that can add functionality or interface to the board on the UEXT
connector; these can be explored here: https://www.olimex.com/Products/Modules/
Some of the above-suggested items can be purchased by Olimex, for instance:
SY0612E – reliable power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXino-MICROSY0612E-CHINA – cheaper power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXinoMICRO
A20-Android-SD – a tested class 10 micro SD card with the latest (by the time of leaving the
Olimex facilities) official Android release
A20-Debian-SD – a tested class 10 micro SD card with the latest (by the time of leaving Olimex
facilities) official Debian Linux release
USB-SERIAL-CABLE-F – USB serial console cable female
USB-MINI-CABLE – standard USB type A to USB type mini cable
A20-VGA-CABLE – adapter from 6-pin connector to 15-pin one
CABLE-IDC40-15cm – cable for LCD to LCD_CON connection
LCD-OLinuXino-4.3TS – low-cost 4.3'' LCD display with touchscreen component – 480×272
LCD-OLinuXino-7TS – low-cost 7'' LCD display with touchscreen component – 800×480
LCD-OLinuXino-10TS – low-cost 10.1'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6 – low-cost 15.6'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6FHD – low-cost 15.6'' LCD display with touchscreen component –1920×1080
SATA-HDD-2.5-500GB – 5GB 2.5'' SATA hard disk
SATA-CABLE-SET – cables that allow the connection of a 2.5'' hard disk to the board
ALUMINIUM-HEATSINK-20×20×6MM – heatsink radiator for better processor heat dissipation2

For boards revision J or newer; the voltage applied to the power jack should be (6-16)V for older board revisions
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2.3 Powering the board
There are four possible ways of powering A20-OLinuXino-MICRO – via external supply providing
7-24V DC3 at the power jack, from 5V USB port via USB_OTG connector, from 3.7V Li-Po battery
via the LIPO_BAT connector, from 5V source applied to 5VEXT test pad at the bottom of the board
and any GND. Note that the board consumes around 300mA of current at 12V when there are no
peripherals connected to the USB hosts, so make sure the power supply is able to provide at least
500mA before plugging. Depending on your preferred way of powering you might need additional
hardware.
The preferred way of powering the board is via the PWR jack with 7-24V DC with a power of atleast 5W (usually 6Vx1A, 12Vx0.5A, etc.). This will make the board fully powered and able topower all the peripherals connected to it.
Important: Not all USB ports would be able to provide enough power for the board. Try using
another USB port or a cable of higher quality. If you have to use USB for powering, consider
externally powered USB port. The best practice is not to count on the mini USB-OTG as a single
power source!
The absolute maximum current available for the board and peripherals when the power supply issupplied via USB-OTG connector is 900mA (no matter how much current you have available,
AXP209 would output no more than 900mA). Of course, a big part of the current is required for theboard itself (without anything extra attached)! For comparison, when the power jack is used to
power the board – the typical current available after the AXP209 is 2500mA!
Note that when powering the board from the USB_OTG, the power provided might be insufficient
to also power a bigger LCD connected to the LCD_con. However, this power option is capable ofdriving the board when using external display connected to the HDMI connector.
The typical consumption of A20-OLinuXino-MICRO is between 100mA and 320mA depending on
the current load and the power voltage applied.
If the board has entered power-down state you can bring it back without restart using the
PWR_BUT. The PWR_BUT is also used to start the board when powered from a Li-Po battery on
the battery connector.
Sometimes when starting Android it is possible the board to enter battery save mode even before
booting fully. Especially, if you have turned off the board without quick boot mode enabled. In thiscase you should press the PWR_BUT for at least 5 seconds which would allow the board to start.
For the European customers we sell two power supply adapters, please check chapter 2.2. We also
sell USB OTG to USB type A cables if you lack such.
Note that it is normal that when the board is powered some integrated circuits might appear hotter
than others. This is perfectly normal for some chips – for instance – voltage regulators and the mainprocessor.

3

For boards revision J or newer; the voltage applied to the power jack should be (6-16)V for older board revisions
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2.4 Prebuilt software
The boards comes with no software uploaded. The board versions with extra flash memory alsocome blank. Typically, the boards with NAND flash memory have the boot regions fixed, allowing
easier Linux install (eMMC boards don't need such preparation).
You can download the latest Linux Debian or Android image from the wiki article of the board anddownload it to a microSD card. You can also install the Linux to the flash memory via install script.
If your board has extra flash memory and you want to boot Android from it refer chapter 6.1.1
USB-OTG communication (NAND firmware repair/update).
The default super user and password combination for the official Linux images is: “root” –”olimex” and the GUI runs under user “olimex” with password “olimex”.

2.5 Button functions
The bellow three buttons usually are supported under both Android and Debian:
PWR_BUT – used to perform software turn off, software turn on; used to turn on board whenpowered by battery – has to be held down for at least couple of seconds to perform each action;
RESET – used for hardware reset of the board – it is not recommended to reset the board this way;
RECOVERY – used to wake up the board from sleep
The following buttons represent functions in the Android (it is possible that not all Android
applications take advantage of the buttons, in such case the button would serve no purpose for thatapplication):
VOL+ – increases the volumeVOL- – lowers the volume
MENU – brings up the main menu
SEARCH – brings up search feature
HOME – shows the home screen; note that HOME is also used to enter bootloader mode forfirmware update
ESC – used to navigate away of a menu
ENTER – to select a choice
It is not recommended to disconnect the power supply (either the USB or the power jack) before
turning off the Android from the either the menus or by holding PWR_BUT. This might lead to filesystem corruption and would require re-writing the image on the flash memory.
How to restore the Android image might be found in chapter “6.1.1 USB-OTG communication(NAND firmware repair/update)”.

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2.6 Interacting with the board
The typical and recommended way of interacting with a stand-alone A20-OLinuXino-MICRO
board is via a 3.3V serial-to-USB cable connected to a personal computer. Such cables are commonand easy to find. Olimex also distributes such cables. Even if you already have such a cable or you
decide to purchase it elsewhere it is advisable to check these product pages as a reference:https://www.olimex.com/Products/Components/Cables/USB-Serial-Cable/USB-Serial-Cable-F/
https://www.olimex.com/Products/Breadboarding/BB-CH340T/open-source-hardware
You need to connect the serial cable lines as follows: RX line to UART0-TX pin; TX line to
UART0-RX pin; GND to GND. Make sure that the serial cable is connected to your personal
computer and recognized properly after driver installation.
Then open a terminal program on the serial (COM) port which the cable is associated with.
After everything else is set, you would need to power the board as explained in “2.3 Powering theboard”.
In addition to the serial communication, you might also use one or more of the following mediums
to interact with the board:
1. a monitor via HDMI connector
2. a monitor via the VGA connector and a VGA adapter
3. SSH via the mini USB connector trough a mini USB cable
4. SSH with a remote computer via LAN connector
5. a display via LCD_CON connector
More details on each of the connections might be found in the consequent sub-chapters.
Note that not all interface options are available for all images. Furthermore, some of the ways ofinteraction are (obviously) not suitable for Android OS. The latest official Debian Linux image
should give you the most possible options of interfacing the board!
Using HDMI, LCD_CON or LAN might require additional configurations. Furthermore, it ispossible to corrupt the output settings over those interfaces and, thus, lose the output medium. In
such cases, you can always use the serial-to-USB cable as a reliable way to establish connection to
the board.
2.6.1 HDMI monitor
All official Debian and Android images for A20-OLinuXino-MICRO have HDMI output by default.
The board would work out-of-the-box with a native HDMI monitor.
Make sure to use a tested HMDI cable.
The default HDMI resolution in the official images is 720p60 (1280×720p at 60Hz). In order tochange that setting the video output on the LCD display you would need to run a configuration
script (if you use Debian Linux) or download a suitable image (if you use Android). Video output
settings are hard-coded in Android images.
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More information about the video output settings and the usage of video settings script might befound in the next chapter “2.7 Changing the default image resolution”.
2.6.2 VGA monitor
All official Debian images for A20-OLinuXino-MICRO have the option to for VGA video output
via the 6-pin VGA connector. If you wish to transform the custom 6-pin connector to a standard 15pin VGA connector you can either use wires or get a ready adapter called “A20-VGA-CABLE”.
More information about the video output settings and the usage of video settings script might befound in the next chapter “2.7 Changing the default image resolution”.
2.6.3 SSH via mini USB cable in Debian
The latest official Debian Linux image allows the use the USB_OTG connector for SSH connection
without the need of a LAN cable or a serial cable. You can use a mini USB cable connected
between your host PC and the on-board mini USB connector. For connection convenience there is a
DHCP server running specifically for USB0 interface. The DHCP server should give IP address tothe new USB0 interface of your host PC so you can make SSH connection from your PC to thedefault board IP address of the USB0 interface – 192.168.2.1.
You can connect to the board using a mini USB cable and an SSH client (if you use Windows you
might use "puTTY", for example) at address 192.168.2.1.
For Windows operating system – upon connection, the board should show up in "Windows Device
Manager" as "RNDIS Ethernet Gadget". You might be asked to install a driver. The drivers can befound online as "RNDIS driver" (Remote Network Driver Interface Specification). The drivers areprovided by Microsoft and they should be available for every Windows distribution – refer to therespective files and articles provided by Microsoft on how to install the required drivers.
2.6.4 SSH via Ethernet
By default the board requests IP address from the network's DHCP server. You need to find what IP
address was assigned to the board before being able to access it over the network. Knowing the IP
address assigned allows you to connect to the board using an SSH client (for example “puTTY”)
then you have to use this address. You can change this policy or the address by editing/etc/network/interface file.
Note that for internet connection you have to set your gateway address in /etc/network/interfaces
file and you have to set your DNS server in /etc/resolv.conf (for example “nameserver
192.168.1.1”)
2.6.5 LCD display
One of the ways to interact with the board is via an external display (with or without touchscreen
component). The 40-pin male connector LCD_CON has the typical 0.1'' pin step. All Olimex
displays have corresponding 40-pin male connector. You would only need a 0.1'' female-female
cable for the hardware connection.
In order to get the video output on the LCD display you might need either to run at least once a
configuration script (if you use Debian Linux) or download a suitable image (if you use Android).
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Video output settings are hard-coded in Android images
More information about the video output settings and the usage of video settings script might befound in the next chapter “2.7 Changing the default image resolution”.

2.7 Changing the default image resolution
Depending on the display or the screen you want to use with the A20-OlinuXino-MICRO, you
might need to apply software changes to the prebuilt Android or Linux image.
The typical OlinuXino user would not need to edit the files, however.
To ease the process of changing the resolution we have compiled a number of Android images
for the Android users (with hard-coded video output settings). Alternatively, for Debian Linux
users, we have provided a shell script that can be executed in order to set preferred video
output and resolution.
For Android that you boot from the NAND memory you would need an image suitable for the
specific resolution. Download locations to such images might be found at the wiki article for theA20 board here: https://www.olimex.com/wiki/A20-OlinuXino-MICRO.
For Linux Debian you would need to execute a shell script to be able to change the resolution. It isvery good idea to use a serial cable for connection to the board from a personal computer since inthis case you are dependent on a video resolution (a cable like USB-SERIAL-CABLE-F). When theboard boots type:./change_display*or./change_display_A20_OlinuXino.shand choose the resolution and the interface (LCD, HDMI or VGA).
The supported resolutions are:
For LCD:
1. 4.3" (480×272)
2. 7" (800×480)
3. 10" (1024×600)
For HDMI:
0. 480i
1. 576i
2. 480p
3. 576p
4. 720p50
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5. 720p60
6. 1080i50
7. 1080i60
8. 1080p24
9. 1080p50
10. 1080p60
For VGA: (note that the VGA signals are routed to custom 6 pin connector and you need to from
adapter to standard VGA connector, Olimex also sells such adapter cables)
0. 1680×1050
1. 1440×900
2. 1360×768
3. 1280×1024
4. 1024×768
5. 800×600
6. 640×480
7. 1920×1080
8. 1280×720
If you decide to edit the configurations yourself the easiest way would be to do it on the board. Thiscan be done offline too (manipulating the image located on the microSD card via a microSD card
reader). The tools for script.bin changing are located in /opt/sunxi-tools directory:#cd /opt/sunxi-tools#./chscr.shThis will convert script.bin file from sdcard to script.fex file and the file will be opened using nano
editor. Now you can change the board modules and parameters, save the changes ("CTRL"+"X";
confirm with "Y") and exit ("CTRL"+"X" again) from nano editor.
#./wrscr.shthis will convert script.fex to script.bin and the script.bin file will be written to the microSD card.
rebootReboot the board and the new settings would be enabled.
Alternatively, you can do the changes on the microSD card off the board. You would need toremove the microSD card and explore it in a microSD card reader. You would need to edit theconfiguration file script.bin and edit the settings inside. This file is usually located in Script.bin can't
be opened in the binary format so you would need to convert it to .fex file format first. There areready-to-use tools that convert script.bin <-> script.fex. Note that script.bin/fex contains
configuration settings and definitions not only for the video output but also for the pin descriptions
and names; power setting and much more. If you really want to modify and customize the default
images (to change port functions, port names, to disable specific peripherals) you would need to beable to edit the script files. Please refer to the following web page for more information:
http://linux-sunxi.org/Fex_Guide
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2.8 Connecting a display and calibrating touchscreen
One of the ways to interact with the board is via an external display (with or without touchscreen
component). The 40-pin male connector LCD_CON has the typical 0.1'' pin step. All Olimex
displays have corresponding 40-pin male connector. You would only need a 0.1'' female-female
cable for the hardware connection.
All LCD displays made by Olimex have at least a 0.1'' LCD connector. Going for an LCD output
you would also need need and a cable to attach the display to the board. The cable is sold separately.
After the hardware connection is established, you need to execute shell script that would change thevideo output of the board to fit the screen (refer to previous chapter).
The displays recommended for the board at the moment of writing might be found in the tablebelow:
Display nameSize of
NativeOfficial
Official
Link to productdisplay
resolution Debian image Android image pagein inches in pixels support
supportLCD-OlinuXino-4.3TS 4.3
480×272
Yes
No
Product pageLCD-OLinuXino-7
7800×480
Yes
Yes
Product pageLCD-OLinuXino-7TS
7800×480
Yes
Yes
Product pageLCD-OLinuXino-10
10.1
1024×600
Yes
Yes
Product pageLCD-OLinuXino-10TS
10.1
1024×600
Yes
Yes
Product pageLCD-OLinuXino-15.6
15.6
1366×768
Yes
No
Product pageLCD-OlinuXino-15.6FHD 15.6
1920×1080 Yes
No
Product pageThe displays whose names contain “TS” - include a resistive touch screen component.
The cable used for connection depends on the specific board you are using and more specifically it
depends on the pitch of the LCD connector of the board. We have two cables – both 40-pins ones
but one for the bigger pitch (0.1'') and the other for the smaller one (0.05''). Each of the displays
listed in the table above has two connectors suitable for both cables:
CABLE-IDC40-15cm – 15cm long cable suitable for 0.1'' step connectors – Product page
CABLE-40-40-10CM – 10cm long cable suitable for 0.05'' step connectors – Product page2.8.1 Android toucshcreen calibration
Calibrating a touchscreen component under Android is pretty straightforward from the Android
application.
Important: initially the boards are calibrated for a specific display and resolution. If you re-write theimage (no matter whether the SD card or the NAND memory) you might need to use a mouse tocalibrate the display initially. It might be impossible to calibrate it only by using the touchcomponent over the display.
2.8.2 Debian touchscreen calibration
Navigate to the system menu and then select "Preferences" -> "Calibrate Touchscreen". Follow theon-screen prompts and remember to save the settings in the xorg.conf.d folder as suggested.
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If there is no “Calibrate Touchscreen” tool, then you are using older official Linux image and you
should execute “ts_calibrate” command, logged as user “olimex” (“su olimex”). The password isalso “olimex”.
The touchscreen calibration under Debian is detailed in the following wiki article:
https://www.olimex.com/wiki/Touch_calibration_official_images

2.9 GPIO under Debian
You can read data from a given GPIO port. The logical ranges are usually as follows:
0V-1V for LOW (or 0)
2.4V-3.3V for HIGH (or 1)
All voltages are measured against ground (GND).
If the input signal is to high, you will at least destroy the port!
The algorithms for writing a value to a GPIO port and reading such a value are pretty similar. The
usage of GPIO ports follows the algorithm (we would use GPIO #49 for demonstration purposes):
1. Export GPIO 49:
echo 49 > /sys/class/gpio/export

Note that you can export GPIOs in range with:for i in `seq 1 1 230`; do echo $i > /sys/class/gpio/export; done

2. Set input/output GPIO 49
2.1 Set input:
echo "in" > /sys/class/gpio/gpio49_ph9/direction

2.2 Set output:
echo "out" > /sys/class/gpio/gpio49_ph9/direction

3. Set value or read value GPIO 49
3.1 Set value:echo 0 > /sys/class/gpio/gpio49_ph9/valueecho 1 > /sys/class/gpio/gpio49_ph9/value

3.2 Read input:
cat /sys/class/gpio/gpio49_ph9/value
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4. Unexport GPIO 49 when finishedecho 49 > /sys/class/gpio/unexport

A very good document on GPIO usage might be found here:
http://www.py6zgp.com/download/A20-GPIO.pdf – the document was created by Dr. Guido Pelz.

2.10 I2C and SPI under Debian
I2C and SPI are both supported in the latest Debian releases. There is respective kernel support for
both. There is a python module called pyA20 might be found here:
https://pypi.python.org/pypi/pyA20
At the same web address you would also find a set of examples on how module is used.

2.11 Software support
We maintain Linux and Android images for SD card which might be downloaded for free andmodified as the user wishes. The latest images and updates are featured at the wiki article of thedevice: https://www.olimex.com/wiki/A20-OLinuXino-MICRO.
We usually try to provide details on how to build the Linux and the Android images at ourwordpress page: http://olimex.wordpress.com/.
Another useful place is the Olimex forums where a lot of people share their experience and advice:https://www.olimex.com/forum/
Additional Android and Linux support and features are added overtime. The Linux support is awork-in-progress and you should not expect full Linux support after the initial volume of suchboards have become available on the market. If you are in a hurry consider the older OLinuXino
designs (which have almost everything supported, have examples available and so on).
You are more than welcome to send or share your suggestions and ideas at our e-mail, the publicforums or irc channel. We would attempt to help in almost every case. We listen to the feedback andif the majority of users suggest a software change or update we try to implement such. Customer
feedback is very important for the overall state of the software support. However, do not expect fullLinux or Android software support.
We can share our experience. We can give you full details for things we have tried. We can point
you to a resource or a guide. We can give you general directions to solving a specific problem orplaces to look for more information. However, we won’t install a piece of software for you or write
custom program for you. We won't provide a specific software solution to a specific software
problem.

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CHAPTER 3: A20-OLINUXINO-MICRO BOARD DESCRIPTION
3. Introduction to the chapter
Here you get acquainted with the main parts of the board. Note the names used on the board might
differ from the names used below to describe them. For the actual names check the A20OLinuXino-MICRO board itself.

3.1 Layout (top view)
The picture below shows the initial revision of A20-OLinuXino-MICRO. Please note that the
NAND memory is present only in the 4GB version of the board.

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3.2 Layout (bottom view)At the bottom of the board there are mainly buttons and the large SD/MMC connector.

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CHAPTER 4: THE ALLWINNER A20 EMBEDDED PROCESSOR
4. Introduction to the chapter
In this chapter is located the information about the heart of OLinuXino – its microcontroller. The
information is a modified version of the datasheet provided by its manufacturers.

4.1 The processor
The A20 chip is very popular and well-known. It has some features that are hard to find in similar
embedded chips – including SATA support and native EMAC and GMAC. The main feature of theA20 processor is the sheer computing power that allows FullHD video playback. The graphicalprocessing unit is also pretty powerful and supported by the default software packages that comewith the OlinuXino boards. The software support for the features in the processor is at pretty goodstate thanks to the efforts of the community and Allwinner themselves.
The full list of features might be found below:
 CPU
 ARM® Cortex™-A7 Dual-Core
 GPU
 ARM® Mali400MP2
 Complies with OpenGL ES 2.0/1.1
 VIDEO
 HD H.264 2160p video decoding Multi-format FHD video decoding, including Mpeg1/2, Mpeg4 SP/ASP GMC, H.263,
H.264,
 VP6/8, AVS jizun, Jpeg/Mjpeg, etc.
 H.264 High Profile 1080p@30fps or 720p@60fps encoding
 3840×1080@30fps 3D decoding, BD/SBS/TAB/FP supported
 Complies with RTSP, HTTP, HLS, RTMP, MMS streaming media protocols
 DISPLAY
 Supports multi-channel HD display
 Integrated HDMI 1.4 transmitter with HDCP support
 CPU/RGB/LVDS LCD interface
 Supports CVBS/YPbPr/VGA
 Integrated TV decoder
 CAMERA Integrated parallel 8-bit I/F YUV sensor
 Integrated 24-bit parallel YUV 444 I/F
 Supports 5M CMOS sensor
 Supports dual sensors
 MEMORY DDR2/DDR3/DDR3L controller
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A20-OLinuXino-MICRO user's manual NAND Flash controller with 64-bit ECC
 AUDIO
 Integrated HI-FI 100dB Audio Codec Dual analog mic amplifiersMore information can be found on Allwinner's web site at the following web-address:
http://www.allwinnertech.com/en/product/A20.html

4.2 Block diagram
The block diagram is taken from Allwinner's web-site.

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CHAPTER 5: CONTROL CIRCUITY
5. Introduction to the chapter
Here you can find information about reset circuit and quartz crystals locations, the power supply
circuit is discussed.

5.1 Reset
The board has hardware reset controlled by the AXP209 power system management IC.
The board should be turned off the standard OS menu (that might be invoked by holding POWER
button or “poweroff” command under Debian) and after the choice is confirmed it is safe to bedisconnected from the power supply unit.

5.2 Clocks
25 MHz quartz crystal Q1 is connected to pins X1 and X2 of the LAN8710A 100Mbit Ethernet
controller.
32 768 Hz (RTC) quartz crystal Q2 is found at pins F1 and F2 of the A20 microcontroller.
24 MHz quartz crystal Q3 is found at pins N22 and N23 of the A20 microcontroller.

5.3 Power supply circuit
The power supply is handled mainly by AXP209 power management system, an Allwinner chip that
goes together with the A20 processor. It is mounted on the board but since it is relatively hard tofind we also sell it separately.
The power supply circuit of A20-OLinuXino-MICRO requires input supply of 7-24V. The
minimum wattage is 5W, and this threshold may raise if using a lot of devices on the USB-HOST(via external hub), a lot of GPIOs and the LCD_CON.
Important: Not all USB ports would be able to provide enough power for the board. Try using
another USB port or a cable of higher quality. If you have to use USB for powering, consider
externally powered USB port. The best practice is not to count on the mini USB-OTG as a single
power source!
The absolute maximum current available for the board and peripherals when the power supply issupplied via USB-OTG connector is 900mA (no matter how much current you have available,
AXP209 would output no more than 900mA). Of course, a big part of the current is required for theboard itself (without anything extra attached)! For comparison, when the power jack is used to
power the board – the typical current available after the AXP209 is 2500mA!

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CHAPTER 6: CONNECTORS AND PINOUT
6. Introduction to the chapter
In this chapter are presented the connectors that can be found on the board all together with their
pinout and notes about them. Jumpers functions are described. Notes and info on specificperipherals are presented. Notes regarding the interfaces are given.

6.1 Communication with the A20
The direct communication method is via the serial interface. Such interface is the UART0 connector(five male pins pointing towards the edge of the board) capable of delivering some information on
the COM port of your computer – and then use your favorite terminal program (puTTy, teraterm,etc) to receive the data/send commands. You can use USB-SERIAL-CABLE-F to interface UART0– that allows you to debug the board with a personal computer with a free USB port.
If you decide to make your own cable you would need to consider that the levels at board's UART0
are in CMOS level (3.3V) and you would need a convertor to bring them to the TTL level of yourcomputer or cable! That is true for the RX and TX also!
It is highly recommended to own a USB-SERIAL-CABLE-F (or similar product) at hand when
debugging – the video output is not always reliable and if you set wrong display settings you might
be unable to recover the settings without a proper UART0 connection.
The more indirect ways of communicating with the board are via peripheral devices – mouse andkeyboard, via a touch screen LCD that is connected on LCD_CON connector and others.
6.1.1 USB-OTG communication (NAND firmware repair/update)
The main way of changing the firmware image located on the NAND of A20-OLinuXino-MICROis via the USB-OTG connector.
We have configured an Android image with settings suitable for A20-OLinuXino-MICRO. You can
upload it to the board with PhoenixSuit software via the USB-OTG. The image is available forusers to try and tweak the settings. The images can be downloaded from the wiki article at:https://www.olimex.com/wiki/A20-OLinuXino-MICRO.
The board variant without NAND needs an SD card with bootable OS – Android or Linux. There
are ready images available for download at the above-linked A20 wiki article.
To repair the image on NAND re-upload it following these easy steps:
1. Install and run PhoenixSuit (can be found in the wiki article for A20).
2. Go to firmware tab of the program and point to a valid Android image (the latest official one may
also be downloaded from the A20 wiki article).
3. Disconnect the power supply and USB cable from the A20 board.
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4. Press and hold RECOVERY button, apply power supply (6-16)V, release RECOVERY button.
5. Connect USB cable to the mini USB connector
6. You will be asked for drivers for the bootloader. Navigate to the folder where you extracted the
PhoenixSuit and install the drivers from the respective executables (or manually point the installer
to the drivers folder in the PhoenixSuit installation path).
7. PhoenixSuit will detect the board and would ask for the method of writing the image. Choose
method of writing the image and confirm your wish to write the image.
8. Wait till upgrade succeeds as shown below:

There are different flavors of the Android and Linux distributions depending on whether you want
to use 50Hz HDMI or 60Hz HDMI or VGA or 7'' display or 10'' display etc. You might need tochange the configuration files inside (depending on your desirable output medium). How to do it isexplained in chapter 2.6 Calibrating a display.
Those images, the software required and further instructions might be found at the wiki page:https://www.olimex.com/wiki/A20-OLinuXino-MICRO.

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6.1.2 UART0, UEXT1, UEXT2 interface
The UART0 might be used for UART communication by default. It is typically used forserial/terminal debug. The UEXTs are typically used for connecting additional modules.
Note that by default only UART0 is defined as a port suitable for serial debug. You can use our
USB-SERIAL-CABLE-F for debugging. UEXT1 and UEXT2 are NOT defined by default.
Consider table below when connecting the USB-SERIAL-CABLE-F according to the wire color
code. The RX line of the cable (GREEN wire) should go to TX line of the target board; the TX lineof the cable (RED wire) should go to the RX line of the target board. The BLUE wire should go to
the target's GND line.
UART0
Pin # Signal name

Processor pin

1 3.3V-

2 UART0-TX

A7

3 UART0-RX

B7

4 GND

UEXT1

Pin #

Signal name

Pin # Signal name

1 3.3V

2GND

3 UART6-TX

4

UART6-RX

5 TWI2-SCK

6

TWI2-SDA

7 SPI2-MISO

8

SPI2-MOSI

9 SPI2-CLK

10

SPI2-CS0

UEXT2
Pin #

Signal name

Pin # Signal name

1 3.3V

2GND

3 UART7-TX

4

UART7-RX

5 TWI1-SCK

6

TWI1-SDA

7 SPI1-MISO

8

SPI1-MOSI

9 SPI1-CLK

10

SPI1-CS0

The UEXT connectors are used as an interface for the Olimex's UEXT modules (usually boards
with MOD- prefix in their commercial names). For more information on UEXT please visit:https://www.olimex.com/Products/Modules/UEXT/resources/UEXT.pdf

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6.2 SD card connectors
There are two SD card connectors on this A20 board. The now common microSD card connector is
located on the top of the board, near the audio in/out connectors.
Note that by default only the micro SD card slot might be used for booting the OS.
However, due to popular demand, there is also an SD/MMC card connector located on the bottomof the board.
Both SD slots might be used simultaneously – there is no data multiplexing lines. For instance –one of them might be used for booting the OS, the other – for storing data.
As a general precaution be careful with the SD cards you purchase. There is a big percentage offake cards due to the low effort required to counterfeit popular brands and the big demand for SD
cards worldwide. When in doubt – try the same operation with another card from another brand.
Olimex sells microSD cards with Linux or Android images, that have been tested – please refer tochapter “2.2 Requirements”. Of course, if you already have a large enough microSD card you candownload the official Linux image from the wiki pages: https://www.olimex.com/wiki/A20OLinuXino-MICRO.
When removing the card, please make sure that you release it from the connector by pushing andNOT by pulling the card directly (this can damage both the connector and the microSD card).

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6.2.1 SD/MMC1 slot
The schematic related to the SD/MMC1 (microSD connector) is shown below:

SD/MMC1 slot is the “smaller” microSD card slot, located on the top of the board.
This slot is typically used for booting the OS, due to the larger capacities of the microSD cards(compared to SD or MMC cards). It is suggested to have an SD card with a proper Linux/Android
image especially if you have ordered a version of the board without NAND memory. It is also
recommended to use Class 10 (10MByte/sec) card for faster read/write operations, lower class cards(especially higher capacity ones) might slow down the whole system.
microSD card connector
Pin # Connector signal name

Wire name (processor pin)

1 DAT2/RES

SD0-D2 (K19)

2 CD/DAT3/CS

SD0-D3 (K20)

3 CMD/DI

-

4 VDD

-

5 CLK/SCLK

SD0-CLK(L20)

6 VSS2-7 DAT0/DO

SD0-D0(M19)

8 DAT1/RES

SD0-D1(M20)

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6.2.2 SD/MMC slot
The schematic related to the SD/MMC1 (SD/MMC connector) is shown below:

The SD/MMC2 slot is located on the back of the PCB and works with the “larger” SD and MMC
cards. The connector was placed by a popular demand.
Note that by default this connector is not suitable for booting OS. Such support is possible but not
implemented in the official software releases.
SD/MMC card connector
Pin # Connector signal name

Wire name (processor pin)

1 CD/DAT3/CS

SDC3-D3 (B16)

2 CMD/DI

SDC3-CMD (A18)

3 VSS1

-

4 VDD

-

5 CLK/SCLK

SDC3-CLK (B18)

6 VSS2-7 DAT0/DO

SDC1-D0 (A17)8 DAT1/RES

SDC1-D1 (B17)9 DAT2/RES

SDC1-D2 (A16)

Additionally, there are the WP and CP switches that are responsible, respectively, for sensing
whether the card is locked for reading and whether there is a card inserted.

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6.3 PWR jack
The power jack used is the typical one used by Olimex in most of our products – the DC barrel jackhas 2.0mm inner pin and 6.3mm hole. More information about the exact component might be foundhere: https://www.olimex.com/wiki/PWRJACK.
You should provide 6 to 16 volts direct current and the required current may vary depending on the
peripherals connected to the board. The power supply you use should be capable of providing atleast 500mA of current.
Pin #Signal name1Power input

2

GND

More info about the power supply can be found in chapter 5 of this manual.

6.4 MIC_IN & HEADPHONES connectors
The part of the schematic related to those connectors is listed below:

Standard MIC_IN jack is mounted for audio input to the board. Note that it is a single channel
MIC_IN. The MIC_IN is a mono input.
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MIC_IN connector
Pin #Signal name

Processor pin

2

MICIN

AC20

3

MICIN

AC20

5

GND

-

The socket can interface standard 3.5 mm phone connector (also known stereo plug or audio plug).
Headphones connector
Pin #Signal name

Processor pin

2

HPOUTL

Y19

3

HPOUTR

W19

5

HPCOM (GND)

AA19, AA20

The connector can interface standard 3.5 mm phone connector (also known stereo plug or audioplug).
The default audio output is set to the HDMI connector (for displays and monitors with built-in
audio speakers). If you wish to use audio out you need to first disconnect the HDMI, boot the board,connect the audio out device (speakers) and finally connect the HDMI.

6.5 USB_OTG connector
The part of the schematic related to the USB_OTG is shown below:

The USB_OTG features Low Loss Power Distribution Switch SY6280 which protects the board incase the devices you have plugged to the USB_OTG attempt to draw more current than 523mA
combined. The maximum current available on the 5V USB_OTG is exactly 523mA.
The SY6280 responsible for the USB_OTG is enabled by USB0-DRV (processor pin C12), thus the
USB_OTG is also controlled by the same signal.
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The hardware part is the cable – to use the OTG as a host you would need a mini USB to USB
adapter cable. Do not confuse micro and mini USB!
The software part is loading a kernel module responsible for the behavior of the board while indevice mode. If such software is not enabled or missing in the official distribution – you would
need, respectively, either to load the module or rebuild the kernel to enable the module. There areseveral modules that you might need depending on what your goals are.
USB_OTG connector
Pin #Signal name

Processor pin

1+5V_OTG_PWR

-

2

UDM0

N20

3

UDP0

N21

4

USB0-IDDET

B5

5

GND

-

The connector case is also grounded.

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6.6 USB_HOST connector
The part of the schematic related to the USB_HOST connector is listed below:

The USB_HOST connector features two levels – called USB1 and USB2 in the schematic. The
connector is situated between the USB_OTG and the HDMI connector. Each of slots them features
a low loss power distribution switch SY6280 which protects the board in case the devices you haveplugged to each level USB_HOST try to draw more than the allowed current.
Please note the pads of capacitors C222 and C223 where you can solder tantalum capacitors(220uF/18V). If you do so you would be able to increase the stability of the powering by the USB
ports when the powered device has high current consumption.
The maximum current available on each slot of the 5V USB_HOST is different! USB1 is capable ofproviding 1000mA of current; while USB2 is capable of providing only 523mA. If you have a
device that draws higher current please plug it into USB1.
The SY6280 responsible for the USB1 is enabled by USB0-DRV1 (processor pin A4).
The SY6280 responsible for the USB2 is enabled by USB0-DRV2 (processor pin A5).

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USB_HOST two-level connector
Pin # Signal name

Processor pin

Pin #Signal name

Processor pin

1.1

5V

Connected to SY628

2.1

5V

Connected to SY628

1.2

UDM1

P20

2.2

UDM2

R20

1.3

UDP1

P21

2.3

UDP2

R21

1.4

GND

-

2.4

GND

-

The GND is common for both levels of the USB_HOST.

6.7 Ethernet
In different hardware revisions of the board we have used a number of different megabit Ethernet
controllers. This is why it is important to test with the latest official image first.
In hardware revision J of the board we switched to Microchip's LAN8710AI-EZK(QFN-32). Notethat the industrial version of the board uses industrial version of the chip. Make sure to refer to thehardware schematic for exact information about the chip used.
If you have problems with the software support for the Ethernet in Linux, consider checking ourlatest build instructions and patches. At the time of writing, a patch to get the Ethernet working canbe found here: https://github.com/OLIMEX/OLINUXINO/blob/master/SOFTWARE/A20/A20build-3.4.103-release-5/a20-phy_1000_100-dram.patch
If you use Linux then the Ethernet connector might be used for SSH connection to the board. If you
lack any other option for debugging it might be hard to guess the correct IP of the board since it has
DHCP enabled by default (especially if you are in a large network). It is good idea to check thedefault settings by exploring the Linux image settings. Those are usually stored in:/etc/network/interfaces
For DHCP you need to enable auto detection and dhcp as shown below:
auto eth0
iface eth0 inet dhcp
For setting a static address please follow the pattern below:
auto eth0
iface eth0 inet static
address 192.168.1.5
netmask 255.255.255.0
gateway 192.168.1.254
The EEPROM memory may be used to store the MAC address.
Important: In some Debian images it is possible that the Ethernet doesn't get auto-detected during
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use the Ethernet connector or you have forgotten to plug a cable the start-up would be greatly
delayed. This might be problem in the first start-up to users counting only on SSH connection. You
can enable the Ethernet after a successful boot-up with:
ifconfing -a
dhclient eth#(as seen after after the ifconfing command)

Important: You can configure static/DHCP-given IP addresses in /etc/network/interfaces

Ethernet
Pin #Signal name

1

TD+

2

TD-

3

VDD

4

NC

5

NC

6

VDD

7

RD+

8

RD-

LED

Color

Usage

Right

Green

Link status

Left

Yellow

Activity status
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6.8 HDMI connector
The part of the schematic that describes the HDMI module is shown below:

Note that there are different Linux images depending whether the HDMI TV works at 50Hz or
60Hz refresh rate. If you board runs Android there is a specific option to set the appropriate HDMI
output.
HDMI connector
Pin #Signal name

Processor pin

1

HTX2P

T23

2

GND

3

Pin #

Signal name

Processor pin

11

GND

-

-

12

HTXCN

W22

HTX2N

T22

13

HCEC

P23

4

HTX1P

U23

14

NA*

NA

5

GND

-

15

HSCL

R23

6

HTX1N

U22

16

HSDA

R22

7

HTX0P

U23

17

GND

-

8

GND

-

18

+5V

-

9

HTX0N

U22

19

HHPD

P22

10

HTXCP

W23

*Pin 14 of the HDMI is not mandatory. In HDMI 1.0-1.3c it is reserved pin; in HDMI 1.4+ it is
optional.
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6.9 VGA connector
You would probably need an adapter cable for the VGA display (6-pin connector to 15-pin female
RGB cable). You can make the cable or the connection yourself or you can purchase the Olimexmade cable: https://www.olimex.com/Products/Components/Cables/A20-VGA-CABLE/. Note thatyou also have to change the script under Debian as explained in chapter 2.6 “Calibrating a display”.
Please note that you would need a specific Android image for the VGA output (with proper display
and output settings). We don't provide such image ready at the moment!
The VGA output has been tested only with the official Debian Linux image so far and it works fine(after selecting the proper mode by executing ./change_display*.sh).
VGA 6-pin connector

VGA 15-pin connector (back numbering)

Connector Signal name Processor pin
pin #Connector pin #(back numbering)

Color code (according
to the image below)

1

VGA-R

AC17

1

RED

2

VGA-B

AB16

3

BLUE

3

VGA-G

AC16

2

GREEN

4

VGA_VSYNC

AC9

14

BLACK

5

VGA_HSYNC

AB9

13

BROWN

6

GND

-

6

PINK

Back view of the 15 pin connector

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6.10 SATA connector and power
The part of the schematic describing the SATA module is shown below:
SATA connector
Pin # Signal name

Processor pin

1

GND

-

2

SATA-TXP

T20

3

SATA-TXM

T21

4

GND

-

5

SATA-RXM

U21

6

SATA-RXP

U20

7

GND

-

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6.11 GPIO ports
There are three GPIO ports which are used generally to access unused by the board's peripherals
pins. However, there are exceptions – some of the pins might be used to easily peripherals or theirlevels.
Most of the pins are already defined in default operating system images. Some of them can be used
as GPIOs, I2C or SPI without much of a problem. Information on the software usage of GPIO ports
might be found in chapters “2.8 GPIO under Debian” and “2.9 I2C and SPI under Debian”.
6.11.1 GPIO-1 (General Purpose Input/Output) 40pin connector**
The GPIO-1 plastic connector has 14 pins. The signal layout is described below:
GPIO-1 connector
Pin # Signal name

Processor pin

Pin # Signal name

Processor pin

1 +5V

-

2 GND

-

3 +3.3V

-

4 GND

-

5 PG0

F20

6 VOL+_BUT

AB23***

7 PG1

E21

8 VOL-_BUT

AB23***

9 PG2

E20

10 MENU_BUT

AB23***

11 PG3D21

12 SEARCH_BUT

AB23***

13 PG4D20

14 HOME_BUT

AB23***

15 PG5

C21

16 ESC_BUT

AB23***

17 PG6E19

18 ENTER_BUT

AB23***

19 PG7

C20

20 TVOUT3

AB17

21 PG8D1922 TVIN0AC18

23 PG9C19

24 TVIN1

AB18

25 PG10D1826 TVIN2

AA17

27 PG11C18

28 TVIN3

Y17

29 VGA_HSYNC

AB9*30 LINEINR

AB21

31 VGA_VSYNC

AC9*32 LINEINL

AB20

33 VGA-G

AC16*

34 FMINR

Y21

35 VGA-B

AB16*

36 FMINL

Y20

37 VGA-R

AC17*

38 MIC1OUTP

AC22

39 LRADC1AB22*40 MIC1OUTN

AC23*Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handledproperly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).

**It was erroneously named GPIO-4 in the first release of the board.
***All Android buttons are connected to an ADC (LRADC) that uses a divider to determine which button is pressed.

The yellow part of the table shows all the signals shared with the 6-pin VGA connector.

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6.11.2 GPIO-2 (General Purpose Input/Output) 40pin connector
The GPIO pins are led out on a separate 40pin connecter. They allow the user to attach additional
hardware, check readings or perform hardware debug. The GPIO-2 connector numbers are printed
at the bottom of the board for your convenience.

GPIO-2 connector
GPIO pin# Signal name

Processor pin#

GPIO pin#

Signal name

Processor pin#

1

5V

-

2

GND

-

3

3.3V

-

4

GND

-

5

TWI0-SCK

A15

6

PE0

E23

7

TWI0-SDA

B15

8

PE1

E22

9

PI0

A20

10

PE2

D23

11

PI1

B20

12

PE3

D22

13

PI2

A19

14

PE4

C23

15

PI3

B19

16

PE5

C22

17

PI10

C17

18

PE6

B23

19

PI11

D17

20

PE7

B22

21

PC3/NCE1

L22*

22

PE8

A23

23

PC7/NRB1

J22*

24

PE9

A22

25

PC16

M21

26

PE10

B21

27

PC17

F23

28

PE11

A21

29

PC18

F22

30

PI14

C15

31

PC23

G19

32

PI15

D15

33

PC24/NQS

F21*

34

UART0-RX

B7*

35

GPIO1

-

36

UART0-TX

A7*

37

GPIO2

-

38

NMI_N

F5

39

GPIO3

-

40

RESET_N

C14

Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handledproperly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).

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6.11.3 GPIO-3 (General Purpose Input/Output) 40pin connector
GPIO-3 connector features the signals of AXP152 on a convenient header. The signals available
might be used to implement power controls on the board – for instance – turning off the device at
specific voltage level or detecting levels.
The JTAG signals might also be accessed at this header.
GPIO-3 connector
GPIO pin# Signal name

Processor pin#

GPIO pin#

Signal name

Processor pin#

1

5V

-

2

GND

-

3

3.3V

-

4

GND

-

5

PH0

A6

6

PB3

B14

7

PH2/LED

C6

8

PB4

A13

9

PH7

B4

10

PB5

B13

11

PH9

D4

12

PB6

A12

13

PH10

A3

14

PB7

B12

15

PH11/SDC3-DET# B3*

16

PB8/SATA-PWR-EN

A11

17

PH12

C3

18

PB10

C11

19

PH13

A2

20

PB11

C10

21

PH14

B2

22

PB12

C9

23

PH15

A1

24

PB13

B11

25

PH16

B1

26

PB14

A10

27

PH17

C1

28

PB15

B10

29

PH18

C2

30

PB16

A9

31

PH19

D1

32

PB17

B9

33

PH20

D2

34

PH24

E3

35

PH21

D3

36

PH25

E4

37

PH22

E1

38

PH26

F3

39

PH23

E2

40

PH27

F4

Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handledproperly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).

The yellow part of the table shows the JTAG signals.
These signals might be conveniently accessed on GPIO-3 connector. These JTAG signals might befound at processor port PB. The pins of the connector are respectively GPIO-3 #26; GPIO-3 #28;
GPIO-3 #30; GPIO-4 #32. More specifically:
PB14 – MS0 (TMS) - GPIO-3 #26
PB15 – CK0 (TCK) - GPIO-3 #28
PB16 – DO0 (TDO) - GPIO-3 #30
PB17 – DI0 (TDI) - GPIO-4 #32
You would also need Vdd and GND which might be found on various places on the board. This
information should be sufficient to establish a hardware connection. The connection would depend
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OLIMEX© 2018

A20-OLinuXino-MICRO user's manualon the debugger you have and the type of its connector (20-pin JTAG, 10-pin JTAG, etc).
Software-wise – the JTAG should be enabled by default but you might also edit the script.bin/fex
file that contains special JTAG part. Please check here: http://linuxsunxi.org/Fex_Guide#.5Bjtag_para.5D; the [jtag_para] part.
The real issue would be finding piece of software that has Allwinner A20 support. The sunxi
community has some experimental configuration files for A10 and A13 boards I believe, but they
were never tested by an Olimex employee.
Furthermore, we have no experience with the JTAG debug, we have not performed any JTAG
debug sessions ourselves.

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6.12 LCD_CON 40pin connector
The LCD_CON pins are led out on a separate 40pin connecter for the ease of connecting an LCD.
We have tested the ability of the board to interact with such a display. They allow the user to attach
additional hardware, check readings or perform hardware debug.
Important: you need additional 40PIN ribbon cable to connect an Olimex display and the
LCD_CON.

LCD_CON connector
GPIO pin# Signal name Processor pin

GPIO pin#

Signal name

Processor pin

1

+5V

-

2

GND

-

3

+3.3V

-

4

GND

-

5

LCD_D16

Y12

6

LCD_D17

AA12

7

LCD_D18

Y11

8

LCD_D19

AA11

9

LCD_D20

Y10

10

LCD_D21

AA10

11

LCD_D22

AB12

12

LCD_D23

AC10

13

LCD_D8

AB11

14

LCD_D9AC1115

LCD_D10

Y15

16

LCD_D11

AA15

17

LCD_D12

Y14

18

LCD_D13

AA14

19

LCD_D14

Y13

20

LCD_D15

AA13

21

LCD_D0

AB15

22

LCD_D1

AC15

23

LCD_D2

AB14

24

LCD_D3

AC1425

LCD_D4

AB13

26

LCD_D5

AC13

27

LCD_D6

AB12

28

LCD_D7AC1229

LCD_HSYNC

AB930

LCD_VSYNC

AC931

LCD_CLK

Y932

LCD_DE

AA9

33

PB3**

B14

34

PB4**

A13

35

LCD_PWR

C436

PB2/PWM0

A14*

37

TPX1

Y22

38

TPX2

AA22

39

TPY1

Y23

40

TPY2

AA23

Signals marked with * are multiplexed with either a peripheral device or another connector. Ensure that the multiplexing is handledproperly on software and/or hardware level (else there would probably occur wrong levels, loss of data, etc).
**Pins 33 and 34 are disconnected by default. You need to place the two resistors marked as NA to establish connection toprocessor's PB3 and PB4.

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The LCD connector is suitable for a number of Olimex displays and touchscreen panels withdifferent native resolution – the smallest available is the 4.3'' one called LCD-OLinuXino-4.3TS
with native screen resolution of 480×272, through the 7'' one named LCD-OlinuXino-7TS with
800×480, to the 1024×600 10.1'' LCD-OLinuXino-10TS.
IMPORTANT:You need to upload new Android image to the board. These images are available here:
https://www.olimex.com/wiki/A20-OLinuXino-MICRO (using an operating system – NAND flash).
In Debian Linux you would need to start a start a shell script to change the built-in the image
resolution settings. Start it with ./change_display_A20_OLinuXino.sh and follow the instructions.
Please refer to chapter 2.5 “Changing the default image resolution” for more details.

6.13 Jumper description
Please note that most the jumpers on the board are SMT type. If you feel insecure of yoursoldering/cutting technique it is better not to try to adjust the jumpers since it is possible to damage
the board.
Board jumpers
Jumper name

Type

Default position

Function

NAND_EPTH

UBOOT

Changes the functionality of the
BOOT/REC button – when in UBOOT
position the button is used toenter bootloader mode (to connect
via USB_OTG). When in REC

VPS-

SMT

Open

Reserved for future use ofdifferent types of NAND memories.

VPS+

SMT

Open

Reserved for future use ofdifferent types of NAND memories.

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6.14 Additional hardware components
The components below are mounted on OLinuXino but are not discussed above. They are listed
here for completeness:
Reset button – used to reset the board
1GB = 2×[4Gb(256M x 16b)] DDR3 SDRAM – the exact memories varies between the hardware
revisions of the board (also the -IND industrial version uses industrial memories). Refer to theschematic of your board for details on the exact memory.
The DDR3 memory part name in the schematic might be outdated. We have used a number ofdifferent but fully compatible DDR3 memories due to supply unavailability. It is always
recommended to check the exact memory name printed on the component itself.
4GB =1×[32Gb(4096M x 8b)] eMMC FLASH – only available on the 4GB version of the board;
the exact memory used varies between hardware revisions of the board. Refer to the schematic ofyour board for details on the exact memory.
PWR_LED – turns on upon powering the board
LED1 – GPIO button
CHGLED – lights when charging a battery connected to the Li-Po battery connector.

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CHAPTER 7: SCHEMATICS
7. Introduction to the chapter
In this chapter is located information about the schematics describing logically and physically A20OLinuXino-MICRO.

7.1 Eagle schematic
OLinuXino schematics may be found it on the OLinuXino's GitHub repository:
https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A20-OLinuXino-MICRO.
You can download the whole repository as .zip without having a GitHub account.
Please note that the schematics of A10 (not to be confused with A10s) and A20 boards are the same
since the two Allwinner processors are pin-to-pin compatible (drop-in replaceable). This means that
schematics for older hardware revisions of A20-OLinuXino-MICRO can be found in the GitHub
folder for A10-OLinuXino-MICRO.
We mostly use Eagle by Cad Soft 4.16r2 for designing. However, the files should be compatible
with the latest Eagle available. Cad Soft offers a trial version of their software that allows you toinspect schematics and board files (without being able to modify them).
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License.
To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/.
If you are looking for a schematic of an older revision of the board and it isn't available at our website you may request it by the support e-mail.

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7.2 Physical dimensions
Note that all dimensions are in mils.

The three highest elements on the board in order from the tallest to the shortest are: USB_HOST
connector – 700mils, capacitors C202 – 650mils, the Ethernet connector – 600mils.
The heights listed above include the PCB height.

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CHAPTER 8: REVISION HISTORY AND SUPPORT
8. Introduction to the chapter
In this chapter you will find the current and the previous version of the document you are reading.
Also the web-page for your device is listed. Be sure to check it after a purchase for the latest
available updates and examples.

8.1 Document revision
Revision, dateA, 30.08.13
B, 16.09.13
C, 18.09.13

D, 30.09.13

E, 02.10.13
F, 16.10.13

G, 24.10.13

H, 27.05.14

Notable changes
Modified page
Initial manual releaseAll
1. Quartz values error fixed15
2. Updated the board revision changes 16
1. Added new additional products
92. Added more information about the 43
SD card booting
1. Added few suggestions for USB boot
2. Added more information about power
9saving mode before complete Android
booting
1. Added more information about11
display setting
2. Added chapter about the VGA
29
3. Added FAQ section
42
Added more information about A20-VGAMultiple pages
CABLE
1. Added more information about SSH 27
connection
2. Added more information about VGA 29
output requirements
3. Improved the FAQ section
41
1. Added more information about USB
10host ports
2. Added new information for latest
41
board revisions

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OLIMEX© 2018

Revision, dateI, 30.05.14

J, 03.11.14

K, 30.01.2015
L, 09.02.2015
M, 10.02.2015
N, 16.02.2015
O, 16.03.2015
P, 23.12.2015

Q, 17.05.2017
R, 29.09.2017
S, 26.10.2017

A20-OLinuXino-MICRO user's manual

Notable changes
Modified page
1. Updated pictures with revision E 1, 14, 15
2. Updated document information toreflect the changes in the board
26, 27
3. Adjusted several paragraphs andtablesMultiple pages
1. Expanded GPIO-3 chapter by adding
JTAG information
2. Added GPIO, I2C and SPI sections
3, 13, 14, 34, 35, 36,
3. Added information about newer
37, 44
Olimex A20 boards boards
4. Added board revision G changes
5. Fixed few spelling mistakes
1. Updated list of suggested displays
8, 27, 46
2. Fixed error about the power jack
Fixed information about the CMOS-TTL
21
convertor
Added chapter “2.6 Interacting with the11board”
1. Information about the Windows driver12
for the tethering
2. Clarified how to prepare a microSD
52
card with Android OS
Updated HDMI parts to reflect the latest
5, 36
schematic
1. Clarified that we no longer load
Android on the 4GB version of the board;All
2. Added information about Debiannandinstall
Added information about new hardware
revisions and versions of the board.
All
Mentioned the change to new Ethernet PHY
controller.
Added info about new board variants
6, 7
Changed external power supply
requirement to 7-24V; updated numerousAll
old articles

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8.2 Board revision
Remember to check the schematics and the board design files to compare the differences.
Revision
B

C

Notable changes
Initial release of the board
1. Resistor matrix RM23 gets replaced by: R133,R134,R135
2. Adjusted the package of H5TQ2G63BFR/MEM4G16D3EABG-125
3. R12 and R15 values changed to 0R
4. NAND_E jumper is changed from PTH to SMD closed
5. 5V_SATA_PWR connector (altogether with 2×2uF) is changed fromWF2S to DW02S and placed near the PWR jack instead of original
position
6. GPIO-4 is now correctly named GPIO-1
7. There is a signal for the power of of the SATA – PB8/SATA-PWR-EN(r136, c216, r138, t1, t137, fet4)
8. A jumper between 5V_E_SATA and 5V_PWR_SATA is added
9. The micro SD card connector is changed

D

Resistor optimizations

E

1. Adjusted and optimized the position of PCB names
2. R16 changed from 237R to 330R, for stability purposes
3. R7, R9 also changed from 237R to 330R, for stability purposes
4. R41 and R104 changed from 1k/1% to 390R for better sync signal
and to improve the VGA signal (allowing it to work at FullHD)FG

H (unreleased)

1. Added 10M resistor in parallel to 32768 crystal else there might
be hang-ups
2. Changed to 32768 crystal to SMD one
3. Few libraries updated
4. Added pads of two tantalum capacitors C222 and C223 near the
USB-host
5. Positions adjusted – A20, NAND, SPIFLASH, LAN, matrix,
capacitors, CARDs and other
6. Added tantalum capacitor 220uF/10V to ISPOUT
7. R48(13k/1%) changed to 6.8k/1% so there would be 1A of current
on USB1; USB2 still gets 523mA maximum
1. Added a 220uF/tant to SATA PWR
2. C216 changed from 100n to 22uF/6.3V, this improves hard-disk
switching on
3. Update of all component libraries. HDMI connector is changed toa new package.
4. Now not placing ESD protection buffers due to hardware
difficulties with their placement
1. Changed the LAN part of the design, added two capactiors
1nF/2kV/X7R/1206, and 1nF/2kV/X7R/1206_or_1M, also the matrix isnow 0402 with 49.9 ohm at 1%.
2. Major polygon changes.
3. Removed HDMI protection circuit(RCLAMP0524P becomes NA).
4. Preparation for memory changes from MEM4G16D3EABG-125 to
K4B4G1646D-BCK0.
5. Position of C95 and C96 slightly adjusted, so that they are notunder GPIO-1 and LAN. USB_OTG polygon changed. USB_HOST polygon
adjusted. Removed few viases.
6. Added few more vias for the VCC.
7. Improved white print. Year and revision updated. Web-site
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8. Power jack package updated.
9. SATA package updated.

I (unreleased)

1. eMMC was added.
2. RTL8201CP(LQFP-48) Ethernet chip replaced with LAN8710AIEZK(QFN-32). Both are MbE PHYs.
3. All libraries were updated.
4. L7, L15, L16 and L17 were changed from FB0805/600R/200mA(201209601) to FB0805/600R/2A.
5. PWR-JAKPWR_JACK_UNI_MILLING_SMALLER_DRILLS changed to PWRJ2mm(YDJ-1136).
6. R98 optimized from 10k/1% to 10k.
7. C195 and C208 optimized 22pF to 33pF.
8. R43 and R103 optimized from 51R to 100R.
9. C123, C126 and C135 were changed from
100uF/16V/LOWESR/105C/6.3x11mm_RM2.5 to 2x47uF/6.3V/0805, i.e.
C123||C240, C126||C222 and C135||C223
10. D6 was renamed to D2 and changed to the D4's package.
11. U13 and U15 were changed from SY8008 to SY8009AAAC(SOT23-5).
12. ODT1, SCKE1, SCS1/SA15 and ZQ1 were connected to the 2 DDR
memories with aim to support bigger sizes if one day A40 isreleased or A10 is used.
13. All resistor matrices: RM1-RM8 and RM16RM21(RA0805_(4X0402)_0R(Board_Mounted)) were removed and the wires
were shortened. The same thing was done for: R106R117(0R(Board_Mounted)).
14. The viases that were between GPIO-1 pads 12/14 were removed.
15. The eMMC was placed over the NAND flash.
16. The cream layer was improved.
17. BKUP connector(HN1x2) was added for AXP's power management
option.
18. RM1 and RM2 were added to enable CTP support for the LCD
connector.
19. MP1482DS was exchanged with MP1584EN(SOIC8E). Because of this,were affected D5, C202, C203 and several other components as well.
20. The files were renamded from 4G to nothing, because theschematic is universal for all boms generated!
21. C217's value was changed from 220uF/10V/TANT to
220uF/10V/TANT_D!
22. Added reset control for the new PHY – C63 becomes NA down from
10uF, R26 becomes NA down from 10K and R25 is now 100R up from NA.

J (released)

1. Rotated RM1 and RM2 at 90 degrees for better soldering.
2. Created separate design for each of the variants of the board(1. commercial temperature range and no flash memory – A20OLinuXino-MICRO; 2. industrial temperature range and no flash
memory – A20-OLinuXino-MICRO-IND; 3. commercial temperature range
and flash memory – A20-OLinuXino-MICRO-EMMC; 4. industrial
temperature range and flash memory – A20-OLinuXino-MICRO-EMMC-IND)- each of these boards would have own hardware revision from now
on.

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8.3 Useful web links and purchase codes
The web pages you can visit for more information about your device are:https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-MICRO-4GB/;
https://www.olimex.com/Products/OLinuXino/A20/A20-OLinuXino-MICRO/.
The wiki article for the board: https://www.olimex.com/wiki/A20-OLinuXino-MICROA place for general questions, FAQ or friendly talk: https://www.olimex.com/forum/.
You can get the latest updates on the software at: https://github.com/OLIMEX/OLINUXINO.
You may may join our IRC channel #olimex @ freenode.net (http://webchat.freenode.net/?
channels=olimex).
ORDER CODES:
A20-OLinuXino-MICRO – the base version of A20-OLinuXino-MICRO, suitable for commercial
temperature range and no external NAND
A20-OLinuXino-MICRO-IND – industrial version (with extended operating temperature range) –has industrial versions of RAM memory and Ethernet controller
A20-OLinuXino-MICRO-e4GB – A20-OLinuXino-MICRO with additional 4GB eMMC memory
A20-OLinuXino-MICRO-e4GB-IND – an industrial version of A20-OLinuXino-MICRO withadditional 4GB eMMC memory
A20-OLinuXino-MICRO-n4GB – a version of A20-OLinuXino-MICRO with additional 4GB
NAND memory
A20-OLinuXino-MICRO-n8GB – a version of A20-OLinuXino-MICRO with additional 4GB
NAND memory
USB-SERIAL-CABLE-F – USB serial console cable female
USB-MINI-CABLE – standard USB type A to USB type mini cable
A20-VGA-CABLE – adapter from 6-pin connector to standard 15-pin VGA one
SY0612E – reliable power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXino-MICROSY0612E-CHINA – cheaper power supply adapter 50Hz (for EU) 12V/0.5A for A20-OLinuXinoMICRO
A20-Android-SD – a tested class 10 micro SD card with the latest (by the time of leaving the
Olimex facilities) official Android release
A20-Debian-SD – a tested class 10 micro SD card with the latest (by the time of leaving Olimex
facilities) official Debian Linux release
LCD-OLinuXino-4.3TS – low-cost 4.3'' LCD display with touchscreen component – 480×272
LCD-OLinuXino-7TS – low-cost 7'' LCD display with touchscreen component – 800×480
LCD-OLinuXino-10TS – low-cost 10.1'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6 – low-cost 15.6'' LCD display with touchscreen component – 1024×600
LCD-OLinuXino-15.6FHD – low-cost 15.6'' LCD display with touchscreen component –1920×1080
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How to purchase?
You can purchase directly from our online shop or from any of our distributors. List of confirmed
Olimex LTD distributors and resellers: https://www.olimex.com/Distributors.
Please visit https://www.olimex.com/ for more info.

8.4 Frequently asked questions (FAQ)
Q: I power my board, it shows a logo and then nothing happens.
A: This might be due to a number of reasons but it is recommended to try the following:
1. Download latest official image from our wiki (either Android or Debian; either for SD card or
flash memory), and upload it to the flash or to an SD card again. There are instructions how to do itin the other questions below. Try if the board works now.
2. Check if your external power supply fits the voltage requirements and if it provides enoughcurrent. Try with different and more powerful power supply.
3. Check the USB hub you are using, plug the USB cable directly to the back of your personal
computer, check the USB cable.
4. The board might enter sleep mode very fast (especially if the Android was turned off without the“Quick Boot” mode being ticked on). Try pressing or holding down the PWR_BUT for a couple ofseconds to wake it up.
Q: How do I write the Linux image to a micro SD card to use with my A20 board?
A: In order to prepare a Linux card under Windows use a free software for writing SD card images
like “Etcher” or “Win32DiskImager”.
Under Linux you can use “dd” to download the image to an SD card - for example, an image withfile name "debian_2g.img" would be downloaded to the SD card connected to a Linux machineusing one of the following commands:# dd bs=4M oflag=sync if=debian_2g.img of=/dev/sdXor# cp debian_2g.img /dev/sdX
where X is the uSD card.
The tips above can also be used to prepare a microSD card with an Android image, suitable for a
microSD card.

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Q: How to detect and enable the Ethernet controller (if it is disabled by default)?
A: You can enable it by following these two steps:
1. Check under what name the LAN is listed with command "ifconfig –a"
2. If, for example, it is under eth0 name, then enable it with: "dhclient eth0"This should enable the Ethernet and then SSH would also be available.
You can also enable auto detection of Ethernet on power-up by uncommenting #auto eth0 in/etc/network/interfaces in the Linux image.
Q: How to generate boot-able SD-card Debian Linux image for A20-OLinuXino-MICRO?
A: Build instructions and required files for the latest Debian images can be found in our GitHub
repository. Here: https://github.com/OLIMEX/OLINUXINO/tree/master/SOFTWARE/A20
Q: How to edit board configurations and definitions in the official Debian Linux?
A: Do you want a custom video resolution output? Do you need a different port definition? Do you
need to change the hardware definitions of the board?
It is explained above in the manual. But you can also visit this wiki article: wiki article.
Q: How to edit board configurations and definitions in the official Android images?
A: There is a wiki article about that, please visit: wiki article.
Q: Is it possible to boot Debian from the extra flash memory? Do you provide such image?
A: Yes, it is possible. Use the latest Debian Jessie image and type "nandinstall" or “emmc”(depending on whether you got a board with NAND or eMMC). More information about NAND
installation can be found in this wiki article: installing Debian Jessie to the 4GB NAND memory.
More information about eMMC installation can be found in this wiki article: installing DebianJessie to the eMMC memory.
There are other people who are also successful in booting Debian from the NAND. Make sure tocheck on the forum. Make sure to check the number of very good and optimized A20-OLinuXino
Debian images by Igor Pečovnik. There are also his instructions for NAND installation of Debian:link to his web-site.
Q: Can I use mainline kernel instead of Sunxi kernel?
A: You can. However, most non-sunxi kernels are headless – no audio or video output aresupported. If you don't need audio or video – go for it – it had been tested and confirmed working(there are installation reports even) here: https://wiki.debian.org/InstallingDebianOn/Allwinner
Q: I have a version of the board with extra flash memory. The board doesn't seem to have
Android loaded.
A: We no longer load Android to the flash memory of the boards. You can upload Android
following the advice above in this document.
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Q: How to install Android on an SD-card?
A: First download one of the official Android images, which might be found in the Android section
above.
Make sure that the download link you visit clearly indicates that the image is suitable for the
microSD card since there are images suitable for NAND memory also. The images suitable for the
microSD memory and those suitable for NAND card are different. However, the upload method is
almost identical – using PhoenixSuit.
There are two types of Android images for microSD card that we usually provide and each of themhas to be downloaded to a microSD card using a different method. The image provided for microSD
card is either the native Android image that can be downloaded to the card via a software tool like
PhoenixSuit (through the board) or an image taken from an already prepared microSD card that
requires to simply write the image (through a microSD card reader).
It is more likely that you have an Android image that requires a simple copy to a card. If that is thecase you can follow the exact steps as for Linux (e.g. using "Win32 Disk Imager" or "dd"command).
In order to prepare a microSD card with a native Android you will need a software tool called
PhoenixSuit and then:• Install and run PhoenixSuit.
• Go to the firmware tab of the program and point to a valid Android image (note that theimages on Gdrive are compressed and you have to extract them to .img files to be able write
them with PhoenixSuit)• Disconnect the power supply and USB cable from the A20 board. Put an SD card in micro SD
holder. We recommend 4GB class 10 card.
• Press and hold RECOVERY button, apply power supply (6-16)V, release RECOVERY button.
• Connect USB cable to the mini USB connector.
• You will be asked for drivers for the boot-loader. Navigate to the folder where you extracted
the PhoenixSuit and install the drivers from the respective executables (or manually point the
installer to the drivers folder in the PhoenixSuit installation path).
• PhoenixSuit will detect the board and would ask for the method of writing the image. Choose
method of writing the image and confirm your wish to write the image.
• Wait till upgrade succeeds
Note that it is not recommended to have your mini USB connected to an external USB hub. Thismight cause delays and might distort the signal levels. Always test with the USB connected straightto the USB ports of your computer.
Important: When Android runs for very first time it takes several minutes to initialize all files andbuffers please do not cut the power supply during this process! Also when fresh image is installed
fast boot may be disabled, which means that when you apply power supply after few seconds
Android will go in sleep mode and you have to press POWER button to start it, you can change tofast boot when you power off there is dialog box asking you if you want next boot to be fast boot,you have to check this box before you power off. Also note that you must do touch screen
calibration when you run Android for very first time which might require a mouse.
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8.5 Product support
For product support, hardware information and error reports mail to: support@olimex.com. All
document or hardware feedback is welcome. Note that we are primarily a hardware company andour software support is limited. Please consider reading the paragraph below about the warranty of
Olimex products.
All goods are checked before they are sent out. In the unlikely event that goods are faulty,
they must be returned, to OLIMEX at the address listed on your order invoice.
OLIMEX will not accept goods that have clearly been used more than the amount needed toevaluate their functionality.
If the goods are found to be in working condition, and the lack of functionality is a result oflack of knowledge on the customers part, no refund will be made, but the goods will be returnedto the user at their expense.
All returns must be authorized by an RMA Number. Email support@olimex.com for authorization
number before shipping back any merchandise. Please include your name, phone number and ordernumber in your email request.
Returns for any unaffected development board, programmer, tools, and cables permitted within 7days from the date of receipt of merchandise. After such time, all sales are considered final.
Returns of incorrect ordered items are allowed subject to a 10% restocking fee. What is
unaffected? If you hooked it to power, you affected it. To be clear, this includes items thathave been soldered to, or have had their firmware changed. Because of the nature of the
products we deal with (prototyping electronic tools) we cannot allow returns of items that havebeen programmed, powered up, or otherwise changed post shipment from our warehouse.
All returned merchandise must be in its original mint and clean condition. Returns on damaged,
scratched, programmed, burnt, or otherwise 'played with' merchandise will not be accepted.
All returns must include all the factory accessories which come with the item. This includes
any In-Circuit-Serial-Programming cables, anti-static packing, boxes, etc.
With your return, enclose your PO#. Also include a brief letter of explanation of why themerchandise is being returned and state your request for either a refund or an exchange.
Include the authorization number on this letter, and on the outside of the shipping box.
Please note: It is your responsibility to ensure that returned goods reach us. Please use areliable form of shipping. If we do not receive your package we will not be held liable.
Shipping and handling charges are not refundable. We are not responsible for any shipping
charges of merchandise being returned to us or returning working items to you.

The full text might be found at https://www.olimex.com/wiki/GTC#Warranty for future reference.

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