HEBI IO Board(Carrier Board version with IO Micro)

Preliminary Specifications and User Information
Revision 0.1, November 2022
Copyright 2022, HEBI Robotics Inc.
Pittsburgh, PA1

Table Of Contents
HEBI IO Board
Preliminary Specifications and User Information
Table Of Contents
Important Notice
ESD (Electrostatic Discharge) Precaution
General Precautions
Power Connections
All Inputs/Outputs
A1-A8: Analog Inputs
B1-B8: Digital Inputs
E1-E8: Digital Outputs
F1-F8: PWM Outputs

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Important Notice
HEBI Robotics Inc. designs and manufactures measurement and automation peripherals thatenable the connection and communication of physical devices to a central control computer. It ispossible, in the case of improper and/or unreasonable use, to damage the IO Board and eventhe control computer or networking equipment to which it is connected. HEBI Robotics Inc. will
not be liable for any such damage.
Except as specified herein, HEBI Robotics Inc. makes no warranties, express or implied,including but not limited to any implied warranty of merchantability or fitness for a particularpurpose. HEBI Robotics Inc. shall not be liable for any special, indirect, incidental orconsequential damages or losses, including loss of data, arising from any cause or theory.
IO Boards and associated products are not designed to be a critical component in life support orsystems where malfunction can reasonably be expected to result in personal injury. Customers
using these products in such applications do so at their own risk and agree to fully indemnify
HEBI Robotics Inc. for any damages resulting from such applications.
HEBI Robotics Inc. assumes no liability for applications assistance or customer product design.
Customers are responsible for their applications using HEBI Robotics Inc. products. To minimize
the risks associated with customer applications, customers should provide adequate design andoperating safeguards. Reproduction of products or written or electronic information from HEBI
Robotics Inc. is prohibited without permission. Reproduction of any of these with alteration is an
unfair and deceptive business practice.
The HEBI IO Board is currently considered a component or sub-assembly, not a complete
product. If it is being used as part of a product to be "placed on the market," the complete
product must comply with any applicable standards.

3ESD (Electrostatic Discharge) Precaution
Although there are no overly sensitive components on the IO Board, there is also no ESD
protection. Care must be taken to not damage the device through ESD by taking the appropriate
precautions.

General Precautions
The HEBI IO Board consists of a bare PCB without an enclosure. Care must be taken to protect
the connections on the bottom of the PCB. Do not operate the board while it is resting on a
conductive surface. Always double check wiring before powering on the board. Never makeconnections while power is on.

Power Connections
Power input to the board can accept between 12V and 48V DC. There is a reverse protection
diode inline with the input. Care must be taken to avoid high voltage transients on the input bus
as it may damage the switching power supply. Power pins have a total rating of 500mA.
Exceeding this amount may damage the on-board regulators.

Inputs/Outputs Screw Terminal Connections
All of the digital input signals will read either 3.3V levels or 5V levels. The digital outputs can beconfigured to use either 3.3V levels or 5V levels by switching the “IO VOLTAGE SELECT”
configuration jumper. Do not move the jumper while the device is powered on.
Please note that all of the digital inputs are connected directly to the processor (STM32F427
from STMicroelectronics). The processor runs at 3.3V, but it has 5V tolerant inputs. The inputs
are not 5V tolerant when the power is disconnected however, so it is important that external 5V
sensors be either powered by this board or incorporate a switching (or level shifting) circuit.
The digital outputs are buffered using a bus transceiver IC made by Texas Instruments. The partnumber is SN74LVC8T245. This IC has a maximum per-pin recommended output sink andsource current rating of 24mA when running on 3.3V and 32mA while running on 5V. However,
the absolute maximum rating for each IC is only 100mA. The IO board uses three of these ICs.
The 8 digital outputs (E1-E8) share one IC, the 8 PWM outputs (F1-F8) share one IC, and thethe serial/SPI outputs share a third IC.

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A1-A8: Analog Inputs
There are 8 analog inputs which have a range of 0-5V, and have a fixed, first order low passfilter with a cutoff frequency of approximately 4.8kHz. All data is sampled at approximately 8kHz
and averaged over 8 cycles. The data registers are only updated at a 1kHz interval, so pollingthe board faster will not produce any benefit. The analog resolution is 12 bits. All of the analog
inputs are buffered with op amps, which have the part number TSV321 and are made by
STMicroelectronics.
It is recommended that for high-accuracy applications, an external calibration procedure is usedas the analog scaling may be slightly off. Additionally, the voltage supply provided by the board
has a fair amount of switching noise, so an external filter on sensitive analog components isrecommended. The ADC readings may also be affected by noisy loads that are connected tothe board. If significant power is drawn from the power bus, there may be a slight offset to thereadings. It is recommended in these situations to perform an additional calibration step for yourtest setup.

B1-B8: Digital Inputs
There are 8 digital inputs, which can handle either 3.3V or 5V levels. Note that the inputs arehigh impedance and will have an undefined value if left unconnected. Proper use of pull-up orpull-down resistors is highly recommended. All of the inputs are directly connected to theprocessor, and must observe its ratings. All digital inputs are sampled at a 1kHz rate.

E1-E8: Digital Outputs
There are 8 digital outputs, which can output either 3.3V or 5V levels depending on the voltage
selection jumper. All digital outputs are set at a 1kHz rate.

F1-F8: PWM Outputs
By default, F1-F8 are configured to switch at approximately 20kHz, which is good for DC motor
control applications. All PWM outputs are updated at a fixed 1kHz interval. The PWM resolution
is 10 bits.

5Document Revision History
0.1 - Initial release6