PCA9539.cpp

/**
 * @file    clsPCA9539.cpp
 * @author     Nico Verduin
 * Original work for PCA9555
 * @updated for PCA9539  AD0ND
 * @date      7-24-2019
 *
 * @mainpage  clsPCA9539
 * Class to enable pinMode(), digitalRead() and digitalWrite() functions on PCA9539 IO expanders
 *
 * Additional input received from Rob Tillaart (9-8-2015)
 *
 * @par License info
 *
 * Class to enable the use of single pins on PCA9539 IO Expander using
 * pinMode(), digitalRead() and digitalWrite().
 *
 * Copyright (C) 2015  Nico Verduin
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Program : clsPCA9555  Copyright (C) 2015  Nico Verduin
 * This is free software, and you are welcome to redistribute it.
 *
 */

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include "clsPCA9539.h"
#include "Wire.h"

/**
 * @name PCA9539 constructor
 * @param address I2C address of the IO Expander
 * Creates the class interface and sets the I2C Address of the port
 */
PCA9555::PCA9555(uint8_t address) {
    _address         = address;        // save the address id
    _valueRegister   = 0;
    Wire.begin();                      // start I2C communication
}

/**
 * @name pinMode
 * @param pin       pin number
 * @param IOMode    mode of pin INPUT or OUTPUT
 * sets the mode of this IO pin
 */
void PCA9539::pinMode(uint8_t pin, uint8_t IOMode) {

    //
    // check if valid pin first
    //
    if (pin <= 15) {
        //
        // now set the correct bit in the configuration register
        //
        if (IOMode == OUTPUT) {
            //
            // mask correct bit to 0 by inverting x so that only
            // the correct bit is LOW. The rest stays HIGH
            //
            _configurationRegister = _configurationRegister & ~(1 << pin);
        } else {
            //
            // or just the required bit to 1
            //
            _configurationRegister = _configurationRegister | (1 << pin);
        }
        //
        // write configuration register to chip
        //
        I2CSetValue(_address, NXP_CONFIG    , _configurationRegister_low);
        I2CSetValue(_address, NXP_CONFIG + 1, _configurationRegister_high);
    }
}
/**
 * @name digitalRead Reads the high/low value of specified pin
 * @param pin
 * @return value of pin
 * Reads the selected pin.
 */
uint8_t PCA9539::digitalRead(uint8_t pin) {
    uint16_t _inputData = 0;
    //
    // we wil only process pins <= 15
    //
    if (pin > 15 ) return 255;
    _inputData  = I2CGetValue(_address, NXP_INPUT);
    _inputData |= I2CGetValue(_address, NXP_INPUT + 1) << 8;
    //
    // now mask the bit required and see if it is a HIGH
    //
    if ((_inputData & (1 << pin)) > 0){
        //
        // the bit is HIGH otherwise we would return a LOW value
        //
        return HIGH;
    } else {
        return LOW;
    }
}

void PCA9539::digitalWrite(uint8_t pin, uint8_t value) {
    //
    // check valid pin first
    //
    if (pin > 15 ){
        _error = 255;            // invalid pin
        return;                  // exit
    }
    //
    // if the value is LOW we will and the register value with correct bit set to zero
    // if the value is HIGH we will or the register value with correct bit set to HIGH
    //
    if (value > 0) {
        //
        // this is a High value so we will or it with the value register
        //
        _valueRegister = _valueRegister | (1 << pin);    // and OR bit in register
    } else {
        //
        // this is a LOW value so we have to AND it with 0 into the _valueRegister
        //
        _valueRegister = _valueRegister & ~(1 << pin);    // AND all bits
    }
    I2CSetValue(_address, NXP_OUTPUT    , _valueRegister_low);
    I2CSetValue(_address, NXP_OUTPUT + 1, _valueRegister_high);
}
//
// low level hardware methods
//

/**
 * @name I2CGetValue
 * @param address Address of I2C chip
 * @param reg    Register to read from
 * @return data in register
 * Reads the data from addressed chip at selected register. \n
 * If the value is above 255, an error is set. \n
 * error codes : \n
 * 256 = either 0 or more than one byte is received from the chip
 */
uint16_t PCA9539::I2CGetValue(uint8_t address, uint8_t reg) {
    uint16_t _inputData;
    //
    // read the address input register
    //
    Wire.beginTransmission(address);          // setup read registers
    Wire.write(reg);
    _error = Wire.endTransmission();
    //
    // ask for 2 bytes to be returned
    //
    if (Wire.requestFrom((int)address, 1) != 1)
    {
        //
        // we are not receing the bytes we need
        //
        return 256;                            // error code is above normal data range
    };
    //
    // read both bytes
    //
    _inputData = Wire.read();
    return _inputData;
}

/**
 * @name I2CSetValue(uint8_t address, uint8_t reg, uint8_t value)
 * @param address Address of I2C chip
 * @param reg    register to write to
 * @param value    value to write to register
 * Write the value given to the register set to selected chip.
 */
void PCA9539::I2CSetValue(uint8_t address, uint8_t reg, uint8_t value){
    //
    // write output register to chip
    //
    Wire.beginTransmission(address);              // setup direction registers
    Wire.write(reg);                              // pointer to configuration register address 0
    Wire.write(value);                            // write config register low byte
    _error = Wire.endTransmission();
}