PROTO16-I2C

16-Bit Digital I/O Card with Prototyping area

Features

• 16-bit Digital I/O card
  • MCP23017 Datasheet - Rev D
  • MCP23017... LOST TWO INPUTS
    • MCP23017 now a 14/16-bit expander, with two of the pins (GPA7 and GPB7) losing their input capabilities
    • The chips look the same, are called the same, and act mostly the same — if you don’t download the latest version of the datasheet (Revision D), you’d never know that there’s been a change
  • 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
• 24LC024 ODAS Personality EEPROM
  • 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

• 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).

Connectors

H1 - Power

• Connector is optional since power can also be brought in via the I2C connector
• Connector is 1x5 of 0.1" header
• Connector is reversible

1. GND
2. PWR
3. GND
4. PWR
5. GND

H2 - Interrupt/Card Present Flag

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

H3 - Address Select

• Sets the I2C offset address of the card
• Three bit address A0, A1, A2

1. A0
2. A1
3. A2

H4 - I2C

• Connector is 2x4 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

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

H6 I2C Termination

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

J1 - DB-25 I/O Connector

• 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

Drivers

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

Arduino Drivers

• LandBoards MCP23017 Library
• Example Software
  • PROTO16I2CBlink - Attach an LED to bit 0 and blink the LED
  • PROTO16I2C_Blink16 - Blinks 16 lines one at a time
  • PROTO16I2CReadInWriteOut - Read an input, set an output bit

Raspberry Pi Drivers

• MCP23017 driver

BeagleBone Black Drivers

• BeagleBone Black Example

ESP32 MicroPython Drivers

• MicroPython MCP23017 driver
• MicroPython Example code
  • testProto16

MicroPython Drivers

• MCP23017 Driver
• MicroPython Examples
  • Blink output bit

CircuitPython (MCP23017) Drivers

• PROTO16_Blink.py - Control the PROTO16-I2C card

Raspberry Pi Pico

• MMBASIC Example Code

Personality EEPROM

• 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
  • PROTO16I2CFAT - EEPROM exercise code
  • ODAS EEPROM Code

Factory Acceptance Tests

Setup

• Runs ODAS Card Test Software on Arduino Nano NANO-BKOUT with I2C-RPT card
• USB running puTTY
  • 9600 baud

Program Personality EEPROM

• 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
Family=ODAS
Company=land.boards.com
Product=PROTO16-I2C

Run I2C Loopback Tests

• Test 'T'

Loopback Test PASS = 1, FAIL = 0

Run Bouncing LEDs

• Select B

Bouncing LEDs - any key to stop

• Use LED card

Rev History

Log of issues

Rev 3

• Convert to Kicad 6
  • No schematic changes
  • New part libraries

• Lots of Silkscreen changes
  • Array area more clearly delineated
  • Signal markings on rear of PCB

Rev X2

• No functional issues
• Add A0 jumper for EEPROM and MCP23017
  • Verified works in Rev X2 (Kickstarter)

Rev X1

• No functional issues

Mechanicals

PROTO16-I2C Assembly Sheet

• PROTO16-I2C Assembly Sheet Rev 3
• PROTO16-I2C Assembly Sheet Rev X2