Do big displays for microcontrollers exist? - Page 1
Forum section: electronics / general

author: e100
author_rank: Frequent Contributor
timestamp: August 30, 2016, 02:59:37 pm
content: I'm working on my first 'big' microcontroller project that needs to display 20 values that can be easily seen at a glance, but I cannot find a suitably large display that has an SPI, I2c or serial interface. Displays over 3" in size seem to only support HDMI/VGA interfaces.At the moment I'm displaying the information on a VT100 terminal emulator on a laptop computer connected via a USB/serial converter but don't want this to be the final solution.Mike

author: Signal32
author_rank: Frequent Contributor
timestamp: August 30, 2016, 03:13:32 pm
content: There are no big displays that have interfaces such as SPI I2C or serial. The reason is because they wouldn't be able to be driven via SPI and certainly not I2C or serial.At 320*240 resolution with 16 bits per pixel and 60fps you would need a ~73 MHZ data stream which is pushing it for SPI.However there are solutions that basically have a high resolution display + built in display driver that expose a SPI/serial port which you can use to send high level GUI commands to (draw text, draw rectangle, etc).Something like:http://www.ampdisplay.com/documents/pdf/DMT48270C043_03WN.pdf

author: mark03
author_rank: Frequent Contributor
timestamp: August 30, 2016, 03:49:04 pm
content: Large display != many pixels.Perhaps an LED display of some sort? I think there are also electrophoretic (e-ink) displays intended for retail price display and that sort of thing, with digits instead of pixels. Problem with e-ink is the market is still too niche, hence the devices tend to be highly proprietary, with top-secret datasheets, back-room deals, no availability in quantities less than one gazillion, etc. I think there were some dev kits (Energy Micro, now Silicon Labs, had one a while back), if you're willing to pay top dollar.I wonder if you could mount one of those small OLED displays from ebay behind a fresnel magnifier.

author: Scrts
author_rank: Frequent Contributor
timestamp: August 30, 2016, 03:53:17 pm
content: Quote from: e100 on August 30, 2016, 02:59:37 pmThis is relatively easy to do with FPGA and a video frame buffer.

author: CaptCrash
author_rank: Regular Contributor
timestamp: August 30, 2016, 03:55:00 pm
content: 4D Systems make a range of reasonable sized displays. Depending on how big you want.Up to about 7" I think and can be driven from micros with a minimum of effort

author: Kilrah
author_rank: Unknown
timestamp: August 30, 2016, 03:57:48 pm
content: Would need to know what he wants to display, what "large" is (are we talking 7" or a scoreboard that has to be seen from the other end of the stadium?) and what kind of resolution he wants. Numbers or alphanumeric? Maybe the "flippy-dot" displays Dave received are an option? 7-segment LED displays?But yeah, apart from specialized industrial style applications (=rather expensive made-to-order stuff) large cheap display usually means high resolution, and the interface that goes with it. Throw a raspi at it and you're done...

author: CJay
author_rank: Super Contributor
timestamp: August 30, 2016, 04:45:55 pm
content: Quote from: Kilrah on August 30, 2016, 03:57:48 pmSeconded, RasPi Zero, cheap and reliable.Or, I have explored those 2.4" SPI displays, you can throw a bitmap at them quickly so I wonder if the OP has enough horsepower available to 'multiplex' them?

author: e100
author_rank: Frequent Contributor
timestamp: August 30, 2016, 04:58:02 pm
content: Quote from: Kilrah on August 30, 2016, 03:57:48 pmReadable at 50cm so the character height needs to be at least 5mm. Being able to distinguish colours at 3 meters would also be good.15 x 15 cm (6" x 6") is probably the minimum size required. Bigger would give more flexibility for displaying debug strings.Someone put together a project that does serial to VT100 emulation with a VGA output.http://geoffg.net/terminal.htmlpresumably because there are no commercial products that do this already?

author: MT
author_rank: Super Contributor
timestamp: August 30, 2016, 06:15:21 pm
content: I have a different aproach, if LCD manufacturers so desire they could implement QUAD SPI who certanily would be able to support large displays.Im just baffled the industry havent abandoned the "yee ol' 8bit MCU interface on the basic 16x2 LCDs etc, etc, etc, boog standard LCD's etc, etc,.

author: RogerRowland
author_rank: Regular Contributor
timestamp: August 30, 2016, 06:24:27 pm
content: Nextion may be an option?https://nextion.itead.cc/

author: janoc
author_rank: Super Contributor
timestamp: August 30, 2016, 06:58:20 pm
content: Quote from: MT on August 30, 2016, 06:15:21 pmWhy would they do that when there is MIPI DSI, DisplayPort, HDMI and who knows how many other standards for this already, with displays widely available (mostly thanks to smartphones/tablets).Sure, you can't drive a MIPI or DisplayPort from an Arduino, but so what? If you are building a system requiring that kind of high resolution display, you would need a lot of RAM and a fast CPU to drive it anyway. At that point you can as well choose a processor that actually has the required interfaces.The old MCU interface on the character LCDs is there because the Hitachi controller is 20 years old, proven quantity, cheap as a dirt and works well enough for the job. If you need a serial interface, adding a shift register is trivial. Change for the sake of change is not always beneficial.

author: MT
author_rank: Super Contributor
timestamp: August 30, 2016, 07:12:59 pm
content: For ordinary MCU's. I dont have HDMI on my STM32 F303, why would i boog up tons of pins on my F429 just to get som paint on the pixel? Some times you might just want to do what the OP want to do without using anything you sugested.Why would there not be an incentive for yet another standard? We all luuuve standards dont we, just one more! Cludgefy a clean design with yet annother shift register is usless, it doesnt cost much to implement 2x16 with serial, actually it allready exist. Progress janoc! Progress!Just found that FT80x and FT81x has QSPI.

author: richardman
author_rank: Frequent Contributor
timestamp: August 30, 2016, 07:17:40 pm
content: We will have a solution that hopefully can demo in early October. I will send you PM and make announcement here when appropriate.

author: MK14
author_rank: Super Contributor
timestamp: August 30, 2016, 07:48:35 pm
content: Quote from: e100 on August 30, 2016, 02:59:37 pmOne solution, is to make the microcontroller a Raspberry PI 3 (£30/$35), but there are others as well. They can then have HDMI outputs, along with graphics chips built in, and operating systems, such as Linux. So that you can readily use normal computer monitors and/or TVs, as big as you like.You can even get ones based on more conventional microcontrollers (with in some cases, lots of I/O and that type of functionality), such as Pic32's, made by e.g. Olimex.Or use a large LED matrix display, with SPI (or other interface types), as the large display, on the non-HDMI equipped microcontroller.

author: David Hess
author_rank: Super Contributor
timestamp: August 30, 2016, 10:29:15 pm
content: What about 7 and 16 segment LED displays?

author: Delta
author_rank: Super Contributor
timestamp: August 30, 2016, 11:54:08 pm
content: K.I.S.S.http://www.411techsystems.com/Extra-Large-Font-20x2-HD44780-LCD-wBack-Light_p_102.html

author: langwadt
author_rank: Super Contributor
timestamp: August 30, 2016, 11:58:01 pm
content: Quote from: e100 on August 30, 2016, 02:59:37 pmhttp://www.buydisplay.com/default/7-inch-lcd-module-capacitive-touch-screen-panel-i2c-spi-serialhttps://github.com/sumotoy/RA8875

author: mariush
author_rank: Super Contributor
timestamp: August 31, 2016, 03:14:07 am
content: Like others said, you could use 14-16 segment digits to display your numbers, and you could add a small microcontroller in your design to act as a "driver" to do the multiplexing (if needed) for your 20 values, but it could get expensive.Here's some examples, they're all 10-14mm tall digits :http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000006097&sort=P_PRICE&eq=N%3D204194%2B110321669%2B2031%26amp%3BNs%3DP_PRICE_FARNELL_UK%257c0%26amp%3BNtpc%3D1%26amp%3BNtpr%3D1&showResults=true&aa=true&pf=110321473,110321669&vw=Lots of alphanumeric LCD displays that have big fonts, up to around 14.5mm per digit, and transmissive or transflective so you can choose if you want to make them with backlight or not .. you can buy them split in rows like these ones here:http://uk.farnell.com/alphanumeric-lcd-displaysor as graphical where you can flip any pixel on the screen:http://uk.farnell.com/graphic-lcd-displaysMost of these work with 4 bit or 8 bit parallel and some have chip select so it's easy to work with them , some have i2c, spi etc

author: Psi
author_rank: Super Contributor
timestamp: August 31, 2016, 06:31:00 am
content: Theres a few projects to draw lines and text on any tv over composite video using an ATMega/arduinoThere is also the max7456 ic which does the same thing in hardware but is text only. It has built in fonts and you control over SPI.Max7456 are expensive from legit sources. Pretty much everyone uses the china knockoff instead.

author: janoc
author_rank: Super Contributor
timestamp: August 31, 2016, 01:05:07 pm
content: Quote from: MT on August 30, 2016, 07:12:59 pmI guess that's a different meaning of progress then - changing from something that works and is widely available to something that almost nobody supports. But I digress ...Also we were talking about large, high resolution screens, not driving 16x2 over HDMI or MIPI. Try to drive something of size of a FullHD display over QSPI and you will see ... There is a reason why almost all smartphone displays are MIPI today.

author: MT
author_rank: Super Contributor
timestamp: August 31, 2016, 01:20:42 pm
content: I dont argue aginst any MIPI whatever,just that QSPI would be neat, but if you dont like QSPI i think you will miss something very useable.I bet there are loads of licenses to pay with the systems you sugested, not to mention all the software layers while there is none particularwith QSPI i recall.Besides this is about OP request not that he wanted to implement MIPI for a LED display.Retire HD44780 now!

author: e100
author_rank: Frequent Contributor
timestamp: August 31, 2016, 01:28:15 pm
content: Thanks to all who gave suggestions.To summarise, 4dsystems and Nextion have 'smart' displays that go up to 7" in size, although setting these up seems like a major development in itself.To go beyond 7" requires the use of a single board Linux computer running a terminal emulator, or a laptop running Windows/Linux.As far as I can tell VT100 style terminals with LCD screens don't exist. Second hand terminals from yesteryear are available, but use CRT screens and are therefore bulky and power hungry.Chromebooks appear to have some degree of support for USB to serial adaptors and the "Beagle term" terminal plugin for the Chrome browser should in theory work, but I don't want to spend the money only to find out that it doesn't.Android tablets don't support any kind of serial interface.Overall it makes me wonder if adding a $15 Wiznet W5100 ethernet interface is the way to go, that way anything that supports TCPIP and a terminal emulator can be used to display information. The W5100 does all the heavy lifting of TCPIP thus conserving memory on the microcontroller.

author: nfmax
author_rank: Super Contributor
timestamp: August 31, 2016, 01:31:09 pm
content: Quote from: e100 on August 30, 2016, 02:59:37 pmYou could use something like a Raspberry Pi or BeagleBoneBlack running Linux and driving an LCD panel over HDMI. You would need an application that reads from the serial port and writes the text to a full screen window (which might be nothing more than a terminal emulator like PuTTY!). Start the application from the init/systemd script and away you go. Sure, there may be far more transistors, computing power, and software in this solution than in your microcontroller application, but so what? It's cheap (and low powered)

author: MK14
author_rank: Super Contributor
timestamp: August 31, 2016, 01:43:58 pm
content: Quote from: e100 on August 31, 2016, 01:28:15 pmDo you want just text/numerical OUTPUT ?Or does it need to input (using a keyboard) into your microcontroller program, as well ?Some of the LCD and VFD type of screens, are similar to VT100 style terminals (WITHOUT the keyboard). Because they can have serial type inputs, such as SPI. The SPI or I2C replacing what use to be a RS232 type of serial connection. But there is more complexity, to get the best results. See LCD datasheets, for information about this. (i.e. not just characters, but special commands, such as clear screen, reverse char draw, etc).If you use a Raspberry PI 3, the output goes straight to the screen, via the HDMI port, by default (once linux has booted and you open a terminal window or full screen). Just like a PC.I.e. you install the (micro) SD card with some kind of Linux on it (readily available for PI), and use GCC for your C program. PrintF/Cout, will then go straight onto your HDMI monitor screen. Via some kind of terminal window or full screen, depending on how the GCC and the resultant executable is being run.

author: MicroBlocks
author_rank: Contributor
timestamp: August 31, 2016, 01:44:59 pm
content: Many displays from 2" to 8" available with SPI.You do not need to push out a whole frame constantly so they can even be driver by a tiny mcu as long as it has a SPI.Those displays have controllers, even font chips.A easy way to get things done is by using a 'micromite'. A PIC32 based system that is programmable in BASIC and for fast function you can add routines written in C.If you need to display some values on a display using BASIC is more then sufficient. Only when you need to do lots of calculations and/or super fast data acquisition you need to go to CCheckout Geoffg.net for more details.

author: Back2Volts
author_rank: Unknown
timestamp: August 31, 2016, 02:09:01 pm
content: Quote from: RogerRowland on August 30, 2016, 06:24:27 pmInteresting warning in the 7" description:Note: there's a small power supply test board and a wire for you to test if the electricity supply is enough or not. Please see below image how to use it.CAUTIONWorking under insufficient power supply condition will damage the Nextion model easily.Blurred screen? Flashing? You may suffer from power shortages. Power off at first possible moment, NO MORE repeated trying to damage your Nextion model.

author: sca
author_rank: Regular Contributor
timestamp: August 31, 2016, 02:17:01 pm
content: Weintek do some HMIs which are easy to interface to (eg serial modbus), simple to program, and relatively cheap compared to a lot of industrial HMI type oojamaflips. Something like the basic i- series perhapshttp://www.weintek.com/globalw/Product/Product_i.aspxsca

author: Delta
author_rank: Super Contributor
timestamp: August 31, 2016, 02:28:54 pm
content: As people have asked, are you needing a large, high resolution graphical display, or just a large font alphanumeric display.Two completely different things!

author: e100
author_rank: Frequent Contributor
timestamp: August 31, 2016, 03:23:34 pm
content: Quote from: Delta on August 31, 2016, 02:28:54 pmLarge font alphanumeric display.Just a small amount of text, updated once per second.Imagine an old SCADA display from the 1970's looking something like thisor thisbut not as fancy as thisThese are fromhttps://scada1966-96.blogspot.com.au/which talks about the evolution of control systems at a steel works from 1966 - 1996.The processing power available for their whole system is similar to the processing power in today's $5 microcontrollers.

author: mubes
author_rank: Regular Contributor
timestamp: August 31, 2016, 03:34:06 pm
content: Buy-Display have SPI (and even I2C!!) displays up to 10.1". Personally I'd avoid I2C but I don't see an issue with the SPI ones if you can keep your writes to the display down....that depends on the intelligence of the controller chip on the other side of the SPI interface. The particular one I just looked at has a RA8876 on board which supports fonts etc. (Video below). I would _not_ advise trying to use one of these for realtime video or something though ..... the comments others have made about the bandwidth of SPI definitely hit home in that circumstance!.(Edited for formatting to move the video)

author: e100
author_rank: Frequent Contributor
timestamp: August 31, 2016, 03:41:15 pm
content: Quote from: sca on August 31, 2016, 02:17:01 pm7" screens with a graphical interface builder similar to the Nextion and 4dsystems.Locally I can buy a Lenovo 10" (1280 x 800) Android tablet for US$160. No support for a serial port, but I can run a VT100 emulator (it's all I need) and talk TCPIP.

author: e100
author_rank: Frequent Contributor
timestamp: August 31, 2016, 04:14:20 pm
content: Quote from: mubes on August 31, 2016, 03:34:06 pmhttp://www.buydisplay.com/default/serial-spi-i2c-10-1-inch-tft-lcd-module-dislay-w-ra8876-optl-touch-panellooks to be the closest yet to what I'm looking for.The driver board is US$69.96 and the actual 10.1" display panel is priced at $9.51. Assuming this is correct, wow, it gives you an idea of the true cost of the LCD display hardware.

author: Delta
author_rank: Super Contributor
timestamp: August 31, 2016, 04:36:52 pm
content: Quote from: e100 on August 31, 2016, 03:23:34 pmhttp://www.reitberger.de/English/Large%20displays/Alphanumeric_LCD_Display_TK/Alphanumeric_LCD_Display_2.htmor a few of thesehttps://www.rapidonline.com/winstar-20-x-4-large-character-alphanumeric-lcd-displays-500165

author: mubes
author_rank: Regular Contributor
timestamp: August 31, 2016, 06:07:50 pm
content: Quote from: e100 on August 31, 2016, 04:14:20 pmNot quite...the headline price is for the LCD, the 9.51 is for the resistive touch overlay. Nonetheless, I think the prices are incredibly low nowadays, even at retail!

author: NEYi
author_rank: Contributor
timestamp: August 31, 2016, 07:34:42 pm
content: If power consumption isn't an issue – VGA is a way to go.I recently tried generating it via SPI, here are the results:Used cheap STM32F103, since everything works on interrupts – there are plenty of free processor time left, you can embed something like this in your project or use the F103 itself for doing all the job.The original idea belongs to some italian guy named Artekit, here's his article with the demo project:http://www.artekit.eu/vga-output-using-a-36-pin-stm32/P.S. I also want to have some big display for my homebrew projects so I ordered a cheap VGA screen from Chinese, costs around 20 bucks.http://www.aliexpress.com/item/7-inch-Raspberry-Pi-IPS-LCD-With-HDMI-VGA-AV-Screen-Display-Monitor-Module-For-Pcduino/32371317014.html?spm=2114.13010608.0.63.pNABuVCan't leave any reviews yet, it's still on it's way.

author: Lukas
author_rank: Frequent Contributor
timestamp: August 31, 2016, 08:19:34 pm
content: HDMI and DSI aren't completely out of reach for your average arm MCU with built-in LCD controller:For HDMI, just hook up an HDMI transmitter to the LCD controller, not much harder than VGA.For DSI, take a look at Mike's work:http://www.electricstuff.co.uk/nanohack.htmlwith a bit of twiddling. There are RGB-to-DSI converters as well.

author: Rasz
author_rank: Super Contributor
timestamp: August 31, 2016, 08:30:34 pm
content: I have two solutions, one is easy and clean, second one is clever, creative and cheap, but complicated and hackish:1/ use TV as a display, its trivial to generate composite signal even with something as weak as attiny2/ you CAN drive LVDS LCD with weak micros, you just need to be clever about it. esot.eric figured out how to do it, here is a project driving laptop 1024x768 LCD over LVDS with attinyhttps://sites.google.com/site/geekattempts/home-1/drive-an-old-laptop-display-from-an-avrhttps://github.com/ericwazhung/avr-lvds-lcdthe trick is to limit resolution (obviously)

author: dannyf
author_rank: Super Contributor
timestamp: August 31, 2016, 09:05:19 pm
content: If you are talking about TV sized large display, the easiest would be to get a micro or mini with HDMI or VGA output and hook it to a TV or monitor.Another route would be one of those pads, Android or iPad. Or even a netbook (plus Chromecast). Much easier and likely cheaper than a customized solution.

author: westfw
author_rank: Super Contributor
timestamp: September 01, 2016, 07:46:38 pm
content: How about simply using a laptop computer? New laptops can be had for under $300 (cheaper than your ascii terminals used to be), cheaper for minimal, used, or chromebooks.

author: NEYi
author_rank: Contributor
timestamp: September 02, 2016, 08:16:40 am
content: Quote from: westfw on September 01, 2016, 07:46:38 pmWell, not everybody lives in the US.300$ seems to be kinda wasteful for others.Quote from: e100 on August 31, 2016, 03:23:34 pmHey e100, I think I found exactly what you could use:https://hackaday.io/project/9992-low-cost-vga-terminal-moduleEmbedded VT100 terminal with 640x480 VGA output on STM32 F0 chip.

author: CM800
author_rank: Frequent Contributor
timestamp: September 02, 2016, 08:26:57 am
content: What is generally considered a good 'solution' for an HMI style project? full RGB, metro style looking.5-7 inch screen or more.I've seen the rather nice units from microelectronics and so on, are they generally in the price range to be expected?They look fine for hobbiest / 1-10 off, but I'm not sure what is the general consensis for a volume solution. (100-10,000 off)

author: obiwanjacobi
author_rank: Super Contributor
timestamp: September 02, 2016, 09:08:02 am
content: Use something like anEVE2chip?That chip does SPI(4) against the MCU and drives VGA on the output.Also offloads a lot of drawing logic from the MCU.

author: janoc
author_rank: Super Contributor
timestamp: September 02, 2016, 12:55:42 pm
content: Quote from: TCWilliamson on September 02, 2016, 08:26:57 amWell, if you are building something large scale, industrial, you buy a ready made HMI unit talking standard protocols, so that your PLCs and what not can use it. But those are expensive - thousands of $ /piece. On the other hand, we are talking machinery that costs hundreds of thousands $, so a kilobuck or two for a screen with a touch interface or keyboard with a panel mount is not much.As an alternative for a simulator of such an industrial machine (i.e. something that will never see the actual factory floor but needs to look and behave like the real thing), we have recently used a RaspberryPi paired with an 15" industrial touch screen monitor - ET1537L from Elo, with the Intellitouch touch screen. Those are originally meant for things like POS terminals, but they are built like tanks.The monitor has DVI and VGA inputs, so driving it from the HDMI on the RasPi is trivial using a simple cable adapter. The touch works out of the box with the open source driver on the RasPi, connected over USB, emulating a mouse. $500 for the monitor + $30 for the RasPi gives you a very professional looking solution. The RasPi was mounted on the back of the monitor using a VESA mount and the entire assembly is installed in a standard industrial metal cabinet that houses the other controls too, using the provided mounting hw. Normally the monitors are powered from a 12V power brick, but we have used a 12V DIN rail supply instead that powers also the RasPi through a small buck converter.Then to build the UI you have a lot of choices in Linux, but my colleagues decided to simply run Chromium on it in kiosk mode and point it to a web page with the necessary controls. Works like a charm.