File content as of revision 0:b6d729ae4f27:

#include "mbed.h"
#include "mcp23s08.h"

#define INPUT 0
#define OUTPUT 1

#define LOW 0
#define HIGH 1

mcp23s08::mcp23s08(PinName mosi, PinName miso, PinName clk, PinName cs_pin,const uint8_t haenAdrs) : SPI(mosi, miso, clk), cs(cs_pin) {
    format(8, 3);
    frequency(2000000);

    postSetup(haenAdrs);

}


void mcp23s08::postSetup(const uint8_t haenAdrs){
    if (haenAdrs >= 0x20 && haenAdrs <= 0x23){//HAEN works between 0x20...0x23
        _adrs = haenAdrs;
        _useHaen = 1;
    } else {
        _adrs = 0;
        _useHaen = 0;
    }
    _readCmd =  (_adrs << 1) | 1;
    _writeCmd = _adrs << 1;
    //setup register values for this chip
    IOCON =     0x05;
    IODIR =     0x00;
    GPPU =      0x06;
    GPIO =      0x09;
    GPINTEN =   0x02;
    IPOL =      0x01;
    DEFVAL =    0x03;
    INTF =      0x07;
    INTCAP =    0x08;
    OLAT =      0x0A;
    INTCON =    0x04;
}

void mcp23s08::begin(bool protocolInitOverride) {
    
    cs=1;
    wait(0.1);
    _useHaen == 1 ? writeByte(IOCON,0b00101000) : writeByte(IOCON,0b00100000);
    /*
    if (_useHaen){
        writeByte(IOCON,0b00101000);//read datasheet for details!
    } else {
        writeByte(IOCON,0b00100000);
    }
    */
    _gpioDirection = 0xFF;//all in
    _gpioState = 0x00;//all low 
}


uint8_t mcp23s08::readAddress(uint8_t addr){
    uint8_t low_byte = 0x00;
    startSend(1);
    SPI::write(addr);
    low_byte = (uint8_t)SPI::write(0x00);
    endSend();
    return low_byte;
}



void mcp23s08::gpioPinMode(uint8_t mode){
    if (mode == INPUT){
        _gpioDirection = 0xFF;
    } else if (mode == OUTPUT){ 
        _gpioDirection = 0x00;
        _gpioState = 0x00;
    } else {
        _gpioDirection = mode;
    }
    writeByte(IODIR,_gpioDirection);
}

void mcp23s08::gpioPinMode(uint8_t pin, bool mode){
    if (pin < 8){//0...7
        mode == INPUT ? _gpioDirection |= (1 << pin) :_gpioDirection &= ~(1 << pin);
        writeByte(IODIR,_gpioDirection);
    }
}

void mcp23s08::gpioPort(uint8_t value){
    if (value == HIGH){
        _gpioState = 0xFF;
    } else if (value == LOW){   
        _gpioState = 0x00;
    } else {
        _gpioState = value;
    }
    writeByte(GPIO,_gpioState);
}


uint8_t mcp23s08::readGpioPort(){
    return readAddress(GPIO);
}

uint8_t mcp23s08::readGpioPortFast(){
    return _gpioState;
}

int mcp23s08::gpioDigitalReadFast(uint8_t pin){
    if (pin < 8){//0...7
        int temp = _gpioState & (1 << pin);
        return temp;
    } else {
        return 0;
    }
}

void mcp23s08::portPullup(uint8_t data) {
    if (data == HIGH){
        _gpioState = 0xFF;
    } else if (data == LOW){    
        _gpioState = 0x00;
    } else {
        _gpioState = data;
    }
    writeByte(GPPU, _gpioState);
}




void mcp23s08::gpioDigitalWrite(uint8_t pin, bool value){
    if (pin < 8){//0...7
        value == HIGH ? _gpioState |= (1 << pin) : _gpioState &= ~(1 << pin);
        writeByte(GPIO,_gpioState);
    }
}

void mcp23s08::gpioDigitalWriteFast(uint8_t pin, bool value){
    if (pin < 8){//0...8
        value == HIGH ? _gpioState |= (1 << pin) : _gpioState &= ~(1 << pin);
    }
}

void mcp23s08::gpioPortUpdate(){
    writeByte(GPIO,_gpioState);
}

int mcp23s08::gpioDigitalRead(uint8_t pin){
    if (pin < 8) return (int)(readAddress(GPIO) & 1 << pin);
    return 0;
}

uint8_t mcp23s08::gpioRegisterReadByte(uint8_t reg){
  uint8_t data = 0;
  startSend(1);
  SPI::write(reg);
  data = (uint8_t)SPI::write(0x00);
  endSend();
  return data;
}


void mcp23s08::gpioRegisterWriteByte(uint8_t reg,uint8_t data){
    writeByte(reg,(uint8_t)data);
}

/* ------------------------------ Low Level ----------------*/
void mcp23s08::startSend(bool mode){
    cs=0;
    mode == 1 ? SPI::write(_readCmd) : SPI::write(_writeCmd);
}

void mcp23s08::endSend(){
    cs=1;
}


void mcp23s08::writeByte(uint8_t addr, uint8_t data){
    startSend(0);
    SPI::write(addr);
    SPI::write(data);
    endSend();
}