I2C 40-I/O port expander

About

• It's a breakout board for the NXP PCA9698
• 40 I/O ports organized in 5 groups of 8
• 3.3v- and 5v-compatible
• Outputs source 10mA, sink 25mA at 5v
• Choose any of 64 I2C addresses, set via AD0-AD2 lines
• 100kHz, 400kHz and 1MHz I2C operation
• Open drain or totem-pole output
• Output enable, reset, and interrupt lines

This board isn't meant to go directly in breadboards. You can solder male or female headers either on the bottom of the board (preferred for installation as a daughter board on main boards) or on the top (preferred for prototyping or wiring to breadboards).

You will need two 2x20 headers and one 2x5 header.

Note that the I2C address is set by the AD0-AD2 lines which get connected to VSS, VDD, SDA, or SCL. See below, or the NXP PCA9698 datasheet section 7.15 for the address map. The table given in the datasheet shows columns A6-A0 and Address for each AD0-AD2 setting. The A6-A0 column gives you the 7-bit address that you must use from Arduinos, while the Address column shows the 8-bit address.

Files

• i2c-expander-40-schematic.pdf: The schematic in PDF format.
• i2c-expander-40-gerbers.zip: Contains Gerber files for board outline, top/bottom layers, top/bottom soldermask, top/bottom silkscreen, solder paste mask ("cream"), and drills. The files were generated from OSH Park's CAM processor for Eagle.
• i2c-expander-40.brd, .sch: Board and schematic files for Eagle (min version 7.5.0)
• i2c-expander-40.lbr: Library file containing devices used in the schematic and board, for Eagle (min version 7.5.0)

AD2-AD0 7-bit address settings

Possible addresses are 0x10-0x2F, 0x50-0x67, 0x70-0x77.

Address	AD2	AD1	AD0	Address	AD2	AD1	AD0
0x10	Vss	SCL	Vss	0x50	SCL	SCL	Vss
0x11	Vss	SCL	Vdd	0x51	SCL	SCL	Vdd
0x12	Vss	SDA	Vss	0x52	SCL	SDA	Vss
0x13	Vss	SDA	Vdd	0x53	SCL	SDA	Vdd
0x14	Vdd	SCL	Vss	0x54	SDA	SCL	Vss
0x15	Vdd	SCL	Vdd	0x55	SDA	SCL	Vdd
0x16	Vdd	SDA	Vss	0x56	SDA	SDA	Vss
0x17	Vdd	SDA	Vdd	0x57	SDA	SDA	Vdd
0x18	Vss	SCL	SCL	0x58	SCL	SCL	SCL
0x19	Vss	SCL	SDA	0x59	SCL	SCL	SDA
0x1A	Vss	SDA	SCL	0x5A	SCL	SDA	SCL
0x1B	Vss	SDA	SDA	0x5B	SCL	SDA	SDA
0x1C	Vdd	SCL	SCL	0x5C	SDA	SCL	SCL
0x1D	Vdd	SCL	SDA	0x5D	SDA	SCL	SDA
0x1E	Vdd	SDA	SCL	0x5E	SDA	SDA	SCL
0x1F	Vdd	SDA	SDA	0x5F	SDA	SDA	SDA
0x20	Vss	Vss	Vss	0x60	SCL	Vss	Vss
0x21	Vss	Vss	Vdd	0x61	SCL	Vss	Vdd
0x22	Vss	Vdd	Vss	0x62	SCL	Vdd	Vss
0x23	Vss	Vdd	Vdd	0x63	SCL	Vdd	Vdd
0x24	Vdd	Vss	Vss	0x64	SDA	Vss	Vss
0x25	Vdd	Vss	Vdd	0x65	SDA	Vss	Vdd
0x26	Vdd	Vdd	Vss	0x66	SDA	Vdd	Vss
0x27	Vdd	Vdd	Vdd	0x67	SDA	Vdd	Vdd
0x28	Vss	Vss	SCL	0x70	SCL	Vss	SCL
0x29	Vss	Vss	SDA	0x71	SCL	Vss	SDA
0x2A	Vss	Vdd	SCL	0x72	SCL	Vdd	SCL
0x2B	Vss	Vdd	SDA	0x73	SCL	Vdd	SDA
0x2C	Vdd	Vss	SCL	0x74	SDA	Vss	SCL
0x2D	Vdd	Vss	SDA	0x75	SDA	Vss	SDA
0x2E	Vdd	Vdd	SCL	0x76	SDA	Vdd	SCL
0x2F	Vdd	Vdd	SDA	0x77	SDA	Vdd	SDA

Example commands

All values are hex.

Write commands

• ADDR 98 00 00 00 00 00 Sets the direction of ports 0-4 to output.
• ADDR 9A 0F Sets the direction of port 2 bits 3-0 to input.
• ADDR 09 22 Writes 0x22 to port 1.
• ADDR 88 11 22 33 44 55 Writes 0x11 to port 0, 0x22 to port 1, 0x33 to port 2, 0x44 to port 3, 0x55 to port 4.
• ADDR 2A 00 Among other things, sets up the output change mode so that a multiport write causes outputs to change all at once after the command, rather than after each byte.

Read commands

• ADDR 0x00 Read from port 0. Every read will return the value of port 0.
• ADDR 0x82 Read starting from port 2. Each read increments the port number, so you could read from port 2, port 3, and port 4 using this command.

Example Arduino code

#include "Wire.h"
#define ADDR 0x10

int setup() {
  Wire.begin(); // Set up Arduino as I2C master

  // Tell board at address 0x10 to set up ports 0-3 for output
  Wire.beginTransmission(ADDR);
  Wire.write({0x98, 0x00, 0x00, 0x00, 0x00}, 5);
  Wire.endTransmission();

  // Tell board at address 0x10 to set up port 4 for input
  Wire.beginTransmission(ADDR);
  Wire.write({0x9C, 0xFF}, 2);
  Wire.endTransmission();
}

int loop() {
  byte data;

  // Write 0x01 to port 0.
  Wire.beginTransmission(ADDR);
  Wire.write({0x08, 0x01}, 2);
  Wire.endTransmission();

  // Read port 4, several times in quick succession
  Wire.beginTransmission(ADDR);
  Wire.write({0x04}, 1);
  Wire.endTransmission();

  Wire.requestFrom(ADDR, 4);
  data = Wire.read();
  data = Wire.read();
  data = Wire.read();
  data = Wire.read();

  delay(1000);

  // Write 0x00 to port 0.
  Wire.beginTransmission(ADDR);
  Wire.write({0x08, 0x00}, 2);
  Wire.endTransmission();

  delay(1000);
}

Further reading

• NXP PCA9698 overview
• NXP PCA9698 datasheet
• Arduino Wire Library, Explored