Simple wrapper for the PCF8574 I/O expansion chip.
The PCF8574 chip operates with the i2c standard and needs proper manipulation to get things right. This library implements a simple interface to use it in your projects.
Currently the code defines the following constants and functions:
PCF_P0...PCF_P7 // These are constants that map to the chip pins
// Initialization
PCF8574();
void begin(); // Default I2C pins
void begin(byte sdaPin, byte sclPin);
// Write operations
void setPinHigh(byte address, PinIndex pin);
void setPinLow(byte address, PinIndex pin);
void togglePin(byte address, PinIndex pin);
void writeWord(byte address, byte value);
// Read operations
char readPin(byte address, PinIndex pin);
int16_t readWord(byte address);It's necessary to instantiate an object and then call begin passing two pins (SDA and SCL) as arguments.
All read/write operations take an address as first argument which is the chip's i2c address (defined in the PCF8574 datasheet). Common values are 0x27, 0x38.