I2CIO-8

Features

• 8 bits of Digital I/O
• I2C interface
• MCP23008 - 8-Bit I/O Expander with I2C Interface
• Base address = 0x20
• Address offset jumpers (0-7)
• Interrupt pin on I2C connectors
• Interrupt LED
• I2C Daisy-chain connectors
• 4 input (or output) jumpers
• 4 LEDs
• 2.7V to 5.5V
• 49x49mm form factor
• (4) #4-40 mounting holes

Headers/Jumpers - Rev X1, X2 Board

J1, J2 - I2C Connectors

• Daisy-chain connectors
• Can ignore second connector
• Pinout

1. GND
2. Power (2.7V-5V)
3. SDA
4. SCL
5. Interrupt (Out)

H5-H8 - GVS connectors

• D4-D7
• Signal/Ground

H8, H9 - I2C Terminators

• Install to terminate SDA/SCL with 2.2K terminator

A0-A2 - I2C Address Jumpers

• Install all 3 for address - 0x20

Headers/Jumpers - Rev 3

J1 - I2C Connector

• Daisy-chain connectors
  • Duplicated all 5 pins
• Right angle 0.1" pitch header
• Can ignore second side of connector is not daisy-chaining other cards
• Pinout

1. GND
2. Power (3.3V or 5V)
3. SDA
4. SCL
5. Interrupt (Active-Low Output)

H1 - I2C Terminators

• Install shunts to terminate SDA/SCL with 2.2K terminators

H2 - I2C Address Jumpers

• Install all 3 shunts for address - 0x20

H3 - D4-D7 Inputs Header

• D4-D7
• Signal/Ground
• 10K Pullups

Indicators

D0-D3 LEDS

• D0-D3 outputs

D9 - INT LED

• Interrupt - LED goes off when interrupt is present (Rev X1, X2 cards)
• Interrupt - LED goes on when interrupt is present (Rev 3 card)

Schematics

• Rev 3 Schematic

Factory Acceptance Test

Test Station Theory of Operations

• Test Station controls the I2C interface on the UUT
• Three tests
  • Internal Test
  • External Loopback Test
  • Bounce an LED Test

Test Station Set-up

• Uses ODAS Test Station V2
• Unit Under Test (UUT)
• Attach Host Computer USB to the Arduino NANO on the Test Station
• Run puTTY on the Host Computer
  • 9600 baud

Card Selection

• puTTY will display the menu

Checking if EEPROM is present on UUT...EEPROM is not present on UUT
Count of I2C devices in range 0x20-0x27 on UUT = 1
Detected MCP23008
Select the board type (Other)
1 - I2CIO8 board
2 - I2CIO8X board
Select board >

• Select 1

Init I2CIO-8 card
C=Card Tests, D=Direct, E=EEPROM, I=access Internal DIGIO32

Running Card Test

• Select Card Tests = "C"
• Select Run Tests = "T"
• Move jumper across the 4 jumper pins H5-H8
• LEDs will correspond
• INT LED will blink on/off
• Observe test results

C=Card Tests, D=Direct, E=EEPROM, I=access Internal DIGIO32
L=Loop/S=Single, T=Test, B=Bounce LEDs, I=UUT Int'l Tests, X=eXit sub-menu
Testing UUT = I2CIO-8
I2CIO8 card tests
Move jumper across H5-H8, observe LEDs D0-D3
Verify Int LED blinks
Hit a key to stop test
Test PASS = 1, FAIL = 0

• Hit ENTER to display menu

L=Loop/S=Single, T=Test, B=Bounce LEDs, I=UUT Int'l Test, X=eXit sub-menu

Running Internal Tests

• Remove loopback cable
• Select Card Tests = "C"
• Select Run Tests = "I"
• Observe test results

L=Loop/S=Single, T=Test, B=Bounce LEDs, I=UUT Int'l Tests, X=eXit sub-menu
UUT Internal card tests
Test PASS = 2, FAIL = 0

• Hit ENTER to display menu

L=Loop/S=Single, T=Test, B=Bounce LEDs, I=UUT Int'l Test, X=eXit sub-menu

Running Blink LED Test

• Select Card Tests = "C"
• Select Run Tests = "B"
• Observe LEDs scanning on the 4 LEDs on the card

L=Loop/S=Single, T=Test, B=Bounce LEDs, I=UUT Int'l Test, X=eXit sub-menu
Bounce a bit across outputs
Bouncing LEDs I2CIO8 - any key to stop

• Hit ENTER to display the menu

Finished bouncing LEDs

Reference

• Arduino Based Test Station
• ODAS Tester Github Repo

MMBASIC Test Station (Rev 3 card)

• UUT
• PiPicoMite01
  • VGA
  • PS/2 Keyboard
  • Test Station SD Card
  • 5V to USB connector
• Type

chdir "lbcards"
load "I2CIO8_Test.bas"
run

• Type 1 to Bounces LED
• Type 2 to loopback jumpers to LEDs
  • Move jumper across D4-7
  • Verify LEDs D0-3 light
  • Verify Int LED illuminates briefly

Drivers/Example Code

Extensive Driver Support for Arduino, Raspberry Pi, MicroPython, ESP-32, Blue Pill Board, Cypress PSoC

Arduino Driver / Examples

• LandBoards_I2CIO8 Arduino Driver code - GitHub repo
  • Importing an Arduino ZIP library
• Example code - GitHub repo

BeagleBone Black

• MCP23008 Example code
  • Enable the I2C devices on the BeagleBone Black Rev C
• Enable the I2C devices on the BeagleBone Black

ESP32

• Github repo - MicroPython Driver

PSOC5 Driver

• DIGIO8Driver.c
• DIGIO8Driver.h

Raspberry Pi Example

• IntrTestRPiHub.py

QT Py Python Example

• I2CIO8.py Demo code - Alternating pattern
• I2CIO8_RW.py - Read jumpers, write back LEDs

Raspberry Pi Pico

MMBASIC

• I2CIO8-ReadWrite.bas
  • Rev 1 and 2 I2CIO-8 cards
• I2CIO8-ReadWriteV3.bas
  • Rev 3 card
  • Active low interrupt requires external pull-up enabled
  • Runs on I2C0 (I2C in MMBASIC) on pins GP0, GP1
  • Interrupt on GP2
• I2CIO8-Bounce.bas

Changes

Rev 3

• The Rev 3 card is functionally the same as rev 1 and 2 cards except the interrupt LED polarity is flipped
  • Active low LED allows for open drain output from multiple cards to be wire-ORed together
  • Requires an external pullup (can typically be done in the I2C master card)

• Change I2C to 2x5 right angle header
  • INT trace on rear side so it could be cut to isolate 2nd daisy-chain
• Combine I2C terminator headers into one 2x2 header
• Re-label GP4-7 inputs as D4-7
• Add 3D parts to model
• Flip polarity on INT LED so it lights when interrupt was present
• Move INT LED closer to board edge
• Rotate LEDS so they can be mounted at a right angle
  • Allows close stacking of cards

Assembly Sheet

• I2CIO-8 Assembly Rev 3 Sheet
• I2CIO-8 Rev X1, X2 Assembly Sheet