PCF8574.cpp

//
//    FILE: PCF8574.cpp
//  AUTHOR: Rob Tillaart
//    DATE: 02-febr-2013
// VERSION: 0.3.1
// PURPOSE: Arduino library for PCF8574 - 8 channel I2C IO expander
//     URL: https://github.com/RobTillaart/PCF8574
//          http://forum.arduino.cc/index.php?topic=184800
//
//      PA0PHH Adjusted for Raspberry PI
//  HISTORY:
//  0.3.1   2021-04-23  Fix for platformIO compatibility
//  0.3.0   2021-01-03  multiWire support - inspirated by mattbue - issue #14
//  0.2.4   2020-12-17  fix #6 tag problem 0.2.3
//  0.2.3   2020-12-14  fix #6 readButton8 ambiguity
//  0.2.2   2020-12-07  add Arduino-ci + start unit test + _wire->h in PCF8574.h
//  0.2.1   2020-06-19  fix library.json
//  0.2.0   2020-05-22  #pragma once; refactor;
//          removed pre 1.0 support
//          added begin(dsa, scl) for ESP32
//          added reverse()
//          
//  0.1.9   2017-02-27  fix warning about return in readButton8()
//  0.1.08  2016-05-20  Merged work of Septillion 
//          Fix/refactor ButtonRead8() - see https://github.com/RobTillaart/Arduino/issues/38
//          missing begin() => mask parameter
//  0.1.07  2016-05-02  (manually merged) Septillion
//          added dataOut so a write() doesn't read first,
//          possibly corrupting a input pin;
//          fixed shift comment, should read 1..7;
//          added begin() to be sure it's in a known state,
//          states could be different if uC is reset and the PCF8574 isn't;
//          added buttonRead() and buttonRead8()
//          which only effect the output while reading
//  0.1.06  (intermediate) added defined errors + refactor rotate
//  0.1.05  2016-04-30  refactor, +toggleMask, +rotLeft, +rotRight
//  0.1.04  2015-05-09  removed ambiguity in read8()
//  0.1.03  2015-03-02  address int -> uint8_t
//  0.1.02  replaced ints with uint8_t to reduce footprint;
//          added default value for shiftLeft() and shiftRight()
//          renamed status() to lastError();
//  0.1.01  added value(); returns last read 8 bit value (cached);
//          value() does not always reflect the latest state of the pins!
//  0.1.00  initial version
//

#include "PCF8574.h"


PCF8574::PCF8574(const uint8_t deviceAddress)
{
  _address    = deviceAddress;
  _dataIn     = 0;
  _dataOut    = 0xFF;
  _buttonMask = 0xFF;
  _error      = PCF8574_OK;
  _connected = false;
  fd = -1;
}

bool PCF8574::begin(uint8_t val)
{
	if ((fd = wiringPiI2CSetup(_address)) < 0)
		return false ;

    if (! isConnected()) return false;
    PCF8574::write8(val);
	_connected = true;
    return true;
}


bool PCF8574::isConnected()
{
    int ret = wiringPiI2CRead(fd);
	return ( ret != -1);
}

uint8_t PCF8574::read8()
{
	int ret = wiringPiI2CReadReg8(_address, (uint8_t)1);
	if (ret < 0)
      {
        _error = PCF8574_I2C_ERROR;
        return _dataIn; // last value
      }
	_dataIn = ret & 0xFF;
    return _dataIn;
}

void PCF8574::write8(const uint8_t value)
{
  int ret = wiringPiI2CWrite(fd, value);
  _dataOut = value;
  _error = ret;
}

uint8_t PCF8574::read(const uint8_t pin)
{
  if (pin > 7)
  {
    _error = PCF8574_PIN_ERROR;
    return 0;
  }
  PCF8574::read8();
  return (_dataIn & (1 << pin)) > 0;
}

void PCF8574::write(const uint8_t pin, const uint8_t value)
{
  if (pin > 7)
  {
    _error = PCF8574_PIN_ERROR;
    return;
  }
  if (value == LOW)
  {
    _dataOut &= ~(1 << pin);
  }
  else
  {
    _dataOut |= (1 << pin);
  }
  write8(_dataOut);
}

void PCF8574::toggle(const uint8_t pin)
{
  if (pin > 7)
  {
    _error = PCF8574_PIN_ERROR;
    return;
  }
  toggleMask(1 << pin);
}

void PCF8574::toggleMask(const uint8_t mask)
{
  _dataOut ^= mask;
  PCF8574::write8(_dataOut);
}

void PCF8574::shiftRight(const uint8_t n)
{
  if ((n == 0) || (_dataOut == 0)) return;
  if (n > 7)         _dataOut = 0;     // shift 8++ clears all, valid...
  if (_dataOut != 0) _dataOut >>= n;   // only shift if there are bits set
  PCF8574::write8(_dataOut);
}

void PCF8574::shiftLeft(const uint8_t n)
{
  if ((n == 0) || (_dataOut == 0)) return;
  if (n > 7)         _dataOut = 0;    // shift 8++ clears all, valid...
  if (_dataOut != 0) _dataOut <<= n;  // only shift if there are bits set
  PCF8574::write8(_dataOut);
}

int PCF8574::lastError()
{
  int e = _error;
  _error = PCF8574_OK;  // reset error after read, is this wise?
  return e;
}

void PCF8574::rotateRight(const uint8_t n)
{
  uint8_t r = n & 7;
  if (r == 0) return;
  _dataOut = (_dataOut >> r) | (_dataOut << (8 - r));
  PCF8574::write8(_dataOut);
}

void PCF8574::rotateLeft(const uint8_t n)
{
  rotateRight(8 - (n & 7));
}

void PCF8574::reverse() // quite fast: 14 shifts, 3 or, 3 assignment.
{
  uint8_t x = _dataOut;
  x = (((x & 0xAA) >> 1) | ((x & 0x55) << 1));
  x = (((x & 0xCC) >> 2) | ((x & 0x33) << 2));
  x =          ((x >> 4) | (x << 4));
  PCF8574::write8(x);
}

//added 0.1.07/08 Septillion
uint8_t PCF8574::readButton8(const uint8_t mask)
{
  uint8_t temp = _dataOut;
  PCF8574::write8(mask | _dataOut);  // read only selected lines
  PCF8574::read8();
  PCF8574::write8(temp);             // restore
  return _dataIn;
}

//added 0.1.07 Septillion
uint8_t PCF8574::readButton(const uint8_t pin)
{
  if (pin > 7)
  {
    _error = PCF8574_PIN_ERROR;
    return 0;
  }

  uint8_t temp = _dataOut;
  PCF8574::write(pin, HIGH);
  uint8_t rtn = PCF8574::read(pin);
  PCF8574::write8(temp);
  return rtn;
}

// -- END OF FILE --