From Land Boards Wiki
Jump to navigation Jump to search


16-Bit Digital I/O Card with Prototyping area[edit]



  • 16-bit Digital I/O card
    • MCP23017 16-bit I2C I/O Expander
    • Strong library support for all major microprocessors for MCP23017
  • I2C Interface - Two Wire Interface
    • Can run at 400 KHz or faster
  • I/O Connector is inexpensive/standard DB-25
    • Fuse protected power output on DB-25 with jumper bypass
  • Large prototyping area
    • Connections at edges to DB-25 and GPIO lines
  • EEPROM for board ID and application specific information
    • Write Enable jumper protects against accidental writes
  • Open Data Acquisition System (ODAS) form factor (width is 95 mm)
  • Host connectors
    • Daisy-chain I2C connector
    • Address select jumper
    • Expandable I2C via I2C-RPT - I2C Repeater
    • Interrupt out/Card Present
    • Power connector (not required for minimal loads)
      • Reversible pinout for safety
    • I2C Termination jumpers for end of I2C chain
  • Power can be 3.3V or 5V
  • 95mm wide Open Data Acquisition System format
  • 6-32 Mounting holes

Prototyping Area[edit]

  • Large prototyping area
  • Ideal for through-hole ICs
  • Extra I/O Rows on both sides
    • One side connects to DB-25 connector
    • Other side connects to MCP23017 pins
  • Prototyping area in the center of the card with power/ground bus up the middle two pins
    • Easy connection to IC Power/Grounds
  • Silkscreen on both sides of the card


  • The above is the top two rows of the prototyping area
  • The pins on the far left are the pin number of the DB-25 connector (ex: Pin 24 is the top left, and pin 11 is in the next row).
  • The next 3 pins are bussed across to each other (the same row)
  • The next column has GND in all column positions
  • The next column has VCC in all column positions
  • The next 3 pins are bussed across to each other (the same row)
  • The far right pin has the DIGIO part connections (blank for the first row and Digital I/O pin 8 in the next point).



H1 - Power[edit]

  • Connector is 1x5 of 0.1" header
  • Connector is reversible
  • Connector is optional since power can also be brought in via the I2C connector
  1. GND
  2. PWR
  3. GND
  4. PWR
  5. GND

H2 - Interrupt/Card Present Flag[edit]

  1. GND
  2. INT0*
  3. CARD_PRESENT* (Low if card is present, should be pulled up by Host card)

H3 - Address Select[edit]

  • Sets the I2C offset address of the card
  • Three bit address A1, A2
  1. A0
  2. A1
  3. A2

H4 - I2C[edit]

  • Connector is 2x5 of 0.1" header
  • Intended to be used for I2C daisy-chain of 4-pin cabling
  • Power can be attached to the connector or power can be provided to the card via the J1 power connector
  • May still want to connect ground
  1. SCL
  2. SDA
  3. VCC
  4. GND

H5 - EEPROM Write Enable[edit]

  • Install to allow writes to EEPROM
  • Remove to prohibit writes to EEPROM

H6 I2C Termination[edit]

  • Two of two position headers
  • Install headers in each position to terminate I2C line
  • There should only be one I2C termination and it should be at the end of the I2C line

J1 - DB-25 I/O Connector[edit]

  • Pins 1, 2, 14 are connected to Ground
  • Pins 12, 13, 25 are connected to Power
  • Pins 3-11 and 15-24 are connected to the Prototype area and are labeled on the PCB

MCP23017 Drivers[edit]

There are quite a I2C drivers for every major microcontroller (Arduino, Raspberry Pi, BeagleBone, etc).

Arduino Drivers[edit]

Raspberry Pi Drivers[edit]

BeagleBone Black Drivers[edit]

ESP32 MicroPython Drivers[edit]

PyBoard MicroPython Drivers[edit]

Linux Drivers[edit]


  • 24LC024 EEPROM
    • 2kbit
    • I2C Serial EEPROM
    • Wide Voltage range (1.8V to 5.5V)
    • 400 KHz operating range
  • 10 mS write cycle time
  • EEPROM has a board ID

Factory Acceptance Tests[edit]



Program Personality EEPROM[edit]

  • Menu driven
  • Auto-detects card
  • If test has been run before
Checking EEPROM for board type...Detected PROTO16-I2C board
R=Read EEPROM, W=Write EEPROM, T=Test DIGIOs, L=Loop Test, B=Bounce LEDs
  • Presents card type list for un-programmed EEPROMs
Checking EEPROM for board type...Company Mismatch
Select the board type
1 - DIGIO16-I2C board
2 - DIGIO-128 board
3 - OptoIn8-I2C board
4 - OptoOut8-I2C board
5 - DIGIO32-I2C board
6 - PROTO16-I2C board
7 - ODAS-PSOC5 board
8 - TBD board
9 - TBD board
Select board > 
  • Select board
Select board > 6
Writing EEPROM
Initializing eep buffer
len of buffer=96
reading block

Run I2C Loopback Tests[edit]

  • Test 'T'
Loopback Test PASS = 1, FAIL = 0

Run Bouncing LEDs[edit]

  • Select B
Bouncing LEDs - any key to stop
  • Use LED card


Issues with Rev X1 board[edit]

Add A0 jumper for EEPROM and MCP23017 Verified works in Rev X2 (Kickstarter)

PROTO16-I2C Assembly Sheet[edit]