TCA6408

Very simple library and example for this I2C-based I/O expander

Tested with Teensy 3.2 and Particle Photon. Should work fine for all Arduino-like MCU's.

Usage

Create an instance:

TCA6408 ioExpanderInputs;

Set it up to use all ports as inputs:

void setup() {
    ioExpanderInputs.begin( TCA6408_ADDR1 ); // Setup on I2C address 0x20
    ioExpanderInputs.writeByte( 0xFF, TCA6408_CONFIGURATION ); // set all channels as outputs (B111111)
}

Read the inputs in the main loop

void loop() {
    uint8_t input_values;// = ioExpanderInputs.readInput(1);
    ioExpanderInputs.readByte(&input_values, TCA6408_INPUT);
}

To setup as 8 output ports, use this syntax:

void setup() {
    ioExpanderOut.begin( TCA6408_ADDR1 );
    ioExpanderOut.writeByte( 0x00, TCA6408_CONFIGURATION ); // set all channels as outputs
}

void loop() {
    setExpanderOutput( 1, 1); // Turn on the first output
    setExpanderOutput( 3, 1); // Turn on the third output
    delay(1000);
    ioExpanderOut.writeByte(0x0, TCA6408_OUTPUT); // turn all off
    delay(1000);
}

void setExpanderOutput(uint8_t output_num, uint8_t value)
{
    uint8_t output_values;
    ioExpanderOut.readByte(&output_values, TCA6408_OUTPUT); // Get current values

    // Update values
    if (value){
        output_values |= (1 << output_num);
    } else {
        output_values &= ~(1 << output_num);
    }

    ioExpanderOut.writeByte(output_values, TCA6408_OUTPUT); // Write values to IO-expander
}