Wire.cpp

/*
  TwoWire.cpp - TWI/I2C library for Wiring & Arduino
  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

  Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
*/

extern "C" {
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
}

#include "Wire.h"

#define I2C_NO_OPTION_FRAME       0xFFFF0000U /*!< XferOptions default value */
// Initialize Class Variables //////////////////////////////////////////////////
uint8_t *TwoWire::rxBuffer = nullptr;
uint8_t TwoWire::rxBufferAllocated = 0;
uint8_t TwoWire::rxBufferIndex = 0;
uint8_t TwoWire::rxBufferLength = 0;

uint8_t TwoWire::txAddress = 0;
uint8_t *TwoWire::txBuffer = nullptr;
uint8_t TwoWire::txBufferAllocated = 0;
uint8_t TwoWire::txBufferIndex = 0;
uint8_t TwoWire::txBufferLength = 0;

uint8_t TwoWire::transmitting = 0;
void (*TwoWire::user_onRequest)(void);
void (*TwoWire::user_onReceive)(int);

// Constructors ////////////////////////////////////////////////////////////////

TwoWire::TwoWire()
{
  _i2c.sda = digitalPinToPinName(SDA);
  _i2c.scl = digitalPinToPinName(SCL);
}

TwoWire::TwoWire(uint8_t sda, uint8_t scl)
{
  _i2c.sda = digitalPinToPinName(sda);
  _i2c.scl = digitalPinToPinName(scl);
}

// Public Methods //////////////////////////////////////////////////////////////

void TwoWire::begin(bool generalCall)
{
  begin(MASTER_ADDRESS, generalCall);
}

void TwoWire::begin(uint8_t address, bool generalCall)
{
  rxBufferIndex = 0;
  rxBufferLength = 0;
  resetRxBuffer();

  txBufferIndex = 0;
  txBufferLength = 0;
  resetTxBuffer();

  transmitting = 0;

  ownAddress = address << 1;

  _i2c.isMaster = (address == MASTER_ADDRESS) ? 1 : 0;

  _i2c.generalCall = (generalCall == true) ? 1 : 0;

  i2c_custom_init(&_i2c, 100000, I2C_ADDRESSINGMODE_7BIT, ownAddress);

  if (_i2c.isMaster == 0) {
    // i2c_attachSlaveTxEvent(&_i2c, reinterpret_cast<void(*)(i2c_t*)>(&TwoWire::onRequestService));
    // i2c_attachSlaveRxEvent(&_i2c, reinterpret_cast<void(*)(i2c_t*, uint8_t*, int)>(&TwoWire::onReceiveService));

    i2c_attachSlaveTxEvent(&_i2c, onRequestService);
    i2c_attachSlaveRxEvent(&_i2c, onReceiveService);
  }
}

void TwoWire::begin(int address, bool generalCall)
{
  begin((uint8_t)address, generalCall);
}

void TwoWire::end(void)
{
  free(txBuffer);
  txBuffer = nullptr;
  txBufferAllocated = 0;
  free(rxBuffer);
  rxBuffer = nullptr;
  rxBufferAllocated = 0;
  i2c_deinit(&_i2c);
}

void TwoWire::setClock(uint32_t frequency)
{
  i2c_setTiming(&_i2c, frequency);
}

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint32_t iaddress, uint8_t isize, uint8_t sendStop)
{
  if (_i2c.isMaster == 1) {
    allocateRxBuffer(quantity);
    // error if no memory block available to allocate the buffer
    if (rxBuffer == nullptr) {
      setWriteError();
      return 0;
    }

    if (isize > 0) {
      // send internal address; this mode allows sending a repeated start to access
      // some devices' internal registers. This function is executed by the hardware
      // TWI module on other processors (for example Due's TWI_IADR and TWI_MMR registers)

      beginTransmission(address);

      // the maximum size of internal address is 3 bytes
      if (isize > 3) {
        isize = 3;
      }

      // write internal register address - most significant byte first
      while (isize-- > 0) {
        write((uint8_t)(iaddress >> (isize * 8)));
      }
      endTransmission(false);
    }

    // perform blocking read into buffer
    uint8_t read = 0;
    if (sendStop != 0) {
      _i2c.handle.XferOptions = I2C_LAST_FRAME;
    } else {
      _i2c.handle.XferOptions = I2C_NO_OPTION_FRAME;
    }
    if (I2C_OK == i2c_master_read(&_i2c, address << 1, rxBuffer, quantity)) {
      read = quantity;
    }

    // set rx buffer iterator vars
    rxBufferIndex = 0;
    rxBufferLength = read;

    return read;
  }

  return 0;
}

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint32_t)0, (uint8_t)0, (uint8_t)sendStop);
}

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}

uint8_t TwoWire::requestFrom(int address, int quantity)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
}

uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
}

void TwoWire::beginTransmission(uint8_t address)
{
  // indicate that we are transmitting
  transmitting = 1;
  // set address of targeted slave
  txAddress = address << 1;
  // reset tx buffer iterator vars
  txBufferIndex = 0;
  txBufferLength = 0;
}

void TwoWire::beginTransmission(int address)
{
  beginTransmission((uint8_t)address);
}

//
//  Originally, 'endTransmission' was an f(void) function.
//  It has been modified to take one parameter indicating
//  whether or not a STOP should be performed on the bus.
//  Calling endTransmission(false) allows a sketch to
//  perform a repeated start.
//
//  WARNING: Nothing in the library keeps track of whether
//  the bus tenure has been properly ended with a STOP. It
//  is very possible to leave the bus in a hung state if
//  no call to endTransmission(true) is made. Some I2C
//  devices will behave oddly if they do not see a STOP.
//
uint8_t TwoWire::endTransmission(uint8_t sendStop)
{
  int8_t ret = 4;
  // check transfer options and store it in the I2C handle
  if (sendStop == 0) {
    _i2c.handle.XferOptions = I2C_FIRST_FRAME;
  } else {
    _i2c.handle.XferOptions = I2C_FIRST_AND_LAST_FRAME;
  }

  if (_i2c.isMaster == 1) {
    // transmit buffer (blocking)
    switch (i2c_master_write(&_i2c, txAddress, txBuffer, txBufferLength)) {
      case I2C_OK :
        ret = 0;
        break;
      case I2C_TIMEOUT :
        ret = 1;
        break;
      default:
        ret = 4;
        break;
    }

    // reset Tx buffer
    resetTxBuffer();

    // reset tx buffer iterator vars
    txBufferIndex = 0;
    txBufferLength = 0;

    // indicate that we are done transmitting
    transmitting = 0;
  }

  return ret;
}

//  This provides backwards compatibility with the original
//  definition, and expected behaviour, of endTransmission
//
uint8_t TwoWire::endTransmission(void)
{
  return endTransmission(true);
}

// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(uint8_t data)
{
  if (transmitting) {
    // in master transmitter mode
    allocateTxBuffer(txBufferLength + 1);
    // error if no memory block available to allocate the buffer
    if (txBuffer == nullptr) {
      setWriteError();
      return 0;
    }
    // put byte in tx buffer
    txBuffer[txBufferIndex] = data;
    ++txBufferIndex;
    // update amount in buffer
    txBufferLength = txBufferIndex;
  } else {
    // in slave send mode
    // reply to master
    if (i2c_slave_write_IT(&_i2c, &data, 1) != I2C_OK) {
      return 0;
    }
  }
  return 1;
}

/**
  * @brief  This function must be called in slave Tx event callback or after
  *         beginTransmission() and before endTransmission().
  * @param  pdata: pointer to the buffer data
  * @param  quantity: number of bytes to write
  * @retval number of bytes ready to write.
  */
size_t TwoWire::write(const uint8_t *data, size_t quantity)
{
  if (transmitting) {
    // in master transmitter mode
    allocateTxBuffer(txBufferLength + quantity);
    // error if no memory block available to allocate the buffer
    if (txBuffer == nullptr) {
      setWriteError();
      return 0;
    }
    // put bytes in tx buffer
    memcpy(&(txBuffer[txBufferIndex]), data, quantity);
    txBufferIndex = txBufferIndex + quantity;
    // update amount in buffer
    txBufferLength = txBufferIndex;
    return quantity;
  } else {
    // in slave send mode
    // reply to master
    if (i2c_slave_write_IT(&_i2c, (uint8_t *)data, quantity) == I2C_OK) {
      return quantity;
    }
  }
  return 0;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::available(void)
{
  return rxBufferLength - rxBufferIndex;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::read(void)
{
  int value = -1;

  // get each successive byte on each call
  if (rxBufferIndex < rxBufferLength) {
    value = rxBuffer[rxBufferIndex];
    ++rxBufferIndex;

    /* Commented as not I think it is not useful
     * but kept to show that it is possible to
     * reset rx buffer when no more data available */
    /*if(rxBufferIndex == rxBufferLength) {
      resetRxBuffer();
    }*/
  }

  return value;
}

// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::peek(void)
{
  int value = -1;

  if (rxBufferIndex < rxBufferLength) {
    value = rxBuffer[rxBufferIndex];
  }

  return value;
}

void TwoWire::flush(void)
{
  rxBufferIndex = 0;
  rxBufferLength = 0;
  resetRxBuffer();
  txBufferIndex = 0;
  txBufferLength = 0;
  resetTxBuffer();
}

// behind the scenes function that is called when data is received
void TwoWire::onReceiveService(uint8_t *inBytes, int numBytes)
{
  // don't bother if user hasn't registered a callback
  if (!user_onReceive) {
    return;
  }

  // don't bother if rx buffer is in use by a master requestFrom() op
  // i know this drops data, but it allows for slight stupidity
  // meaning, they may not have read all the master requestFrom() data yet
  if (rxBufferIndex < rxBufferLength) {
    return;
  }

  allocateRxBuffer(numBytes);
  // error if no memory block available to allocate the buffer
  if (rxBuffer == nullptr) {
    Error_Handler();
  }

  // copy twi rx buffer into local read buffer
  // this enables new reads to happen in parallel
  memcpy(rxBuffer, inBytes, numBytes);
  // set rx iterator vars
  rxBufferIndex = 0;
  rxBufferLength = numBytes;
  // alert user program
  user_onReceive(numBytes);
}

// behind the scenes function that is called when data is requested
void TwoWire::onRequestService(void)
{
  // don't bother if user hasn't registered a callback
  if (!user_onRequest) {
    return;
  }

  // reset tx buffer iterator vars
  // !!! this will kill any pending pre-master sendTo() activity
  txBufferIndex = 0;
  txBufferLength = 0;
  // alert user program
  user_onRequest();
}

// sets function called on slave write
void TwoWire::onReceive(void (*function)(int))
{
  user_onReceive = function;
}

// sets function called on slave read
void TwoWire::onRequest(void (*function)(void))
{
  user_onRequest = function;
}

/**
  * @brief  Allocate the Rx/Tx buffer to the requested length if needed
  * @note   Minimum allocated size is BUFFER_LENGTH)
  * @param  length: number of bytes to allocate
  */
void TwoWire::allocateRxBuffer(size_t length)
{
  if (rxBufferAllocated < length) {
    // By default we allocate BUFFER_LENGTH bytes. It is the min size of the buffer.
    if (length < BUFFER_LENGTH) {
      length = BUFFER_LENGTH;
    }
    uint8_t *tmp = (uint8_t *)realloc(rxBuffer, length * sizeof(uint8_t));
    if (tmp != nullptr) {
      rxBuffer = tmp;
      rxBufferAllocated = length;
    } else {
      _Error_Handler("No enough memory! (%i)\n", length);
    }
  }
}

inline void TwoWire::allocateTxBuffer(size_t length)
{
  if (txBufferAllocated < length) {
    // By default we allocate BUFFER_LENGTH bytes. It is the min size of the buffer.
    if (length < BUFFER_LENGTH) {
      length = BUFFER_LENGTH;
    }
    uint8_t *tmp = (uint8_t *)realloc(txBuffer, length * sizeof(uint8_t));
    if (tmp != nullptr) {
      txBuffer = tmp;
      txBufferAllocated = length;
    } else {
      _Error_Handler("No enough memory! (%i)\n", length);
    }
  }
}

/**
  * @brief  Reset Rx/Tx buffer content to 0
  */
inline void TwoWire::resetRxBuffer(void)
{
  if (rxBuffer != nullptr) {
    memset(rxBuffer, 0, rxBufferAllocated);
  }
}

inline void TwoWire::resetTxBuffer(void)
{
  if (txBuffer != nullptr) {
    memset(txBuffer, 0, txBufferAllocated);
  }
}

// Preinstantiate Objects //////////////////////////////////////////////////////

TwoWire Wire = TwoWire(); //D14-D15