Wire.cpp

/*
 * TWI/I2C library for Arduino Zero
 * Copyright (c) 2015 Arduino LLC. All rights 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
 */

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

#include <Arduino.h>
#include <wiring_private.h>

#include "Wire.h"

using namespace arduino;

TwoWire::TwoWire(SERCOM * s, uint8_t pinSDA, uint8_t pinSCL)
{
  this->sercom = s;
  this->_uc_pinSDA=pinSDA;
  this->_uc_pinSCL=pinSCL;
  transmissionBegun = false;
}

void TwoWire::begin(void) {
  //Master Mode
  sercom->initMasterWIRE(TWI_CLOCK);
  sercom->enableWIRE();

  pinPeripheral(_uc_pinSDA, g_APinDescription[_uc_pinSDA].ulPinType);
  pinPeripheral(_uc_pinSCL, g_APinDescription[_uc_pinSCL].ulPinType);
}

void TwoWire::begin(uint8_t address, bool enableGeneralCall) {
  //Slave mode
  sercom->initSlaveWIRE(address, enableGeneralCall);
  sercom->enableWIRE();

  pinPeripheral(_uc_pinSDA, g_APinDescription[_uc_pinSDA].ulPinType);
  pinPeripheral(_uc_pinSCL, g_APinDescription[_uc_pinSCL].ulPinType);
}

void TwoWire::setClock(uint32_t baudrate) {
  sercom->disableWIRE();
  sercom->initMasterWIRE(baudrate);
  sercom->enableWIRE();
}

void TwoWire::end() {
  sercom->disableWIRE();
}

size_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool stopBit)
{
  if(quantity == 0)
  {
    return 0;
  }

  size_t byteRead = 0;

  rxBuffer.clear();

  if(sercom->startTransmissionWIRE(address, WIRE_READ_FLAG))
  {
    // Read first data
    rxBuffer.store_char(sercom->readDataWIRE());

    bool busOwner;
    // Connected to slave
    for (byteRead = 1; byteRead < quantity && (busOwner = sercom->isBusOwnerWIRE()); ++byteRead)
    {
      sercom->prepareAckBitWIRE();                          // Prepare Acknowledge
      sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_READ); // Prepare the ACK command for the slave
      rxBuffer.store_char(sercom->readDataWIRE());          // Read data and send the ACK
    }
    sercom->prepareNackBitWIRE();                           // Prepare NACK to stop slave transmission
    //sercom->readDataWIRE();                               // Clear data register to send NACK

    if (stopBit && busOwner)
    {
      sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);   // Send Stop unless arbitration was lost
    }

    if (!busOwner)
    {
      byteRead--;   // because last read byte was garbage/invalid
    }
  }

  return byteRead;
}

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

void TwoWire::beginTransmission(uint8_t address) {
  // save address of target and clear buffer
  txAddress = address;
  txBuffer.clear();

  transmissionBegun = true;
}

// Errors:
//  0 : Success
//  1 : Data too long
//  2 : NACK on transmit of address
//  3 : NACK on transmit of data
//  4 : Other error
uint8_t TwoWire::endTransmission(bool stopBit)
{
  transmissionBegun = false ;

  // Start I2C transmission
  if ( !sercom->startTransmissionWIRE( txAddress, WIRE_WRITE_FLAG ) )
  {
    sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
    return 2 ;  // Address error
  }

  // Send all buffer
  while( txBuffer.available() )
  {
    // Trying to send data
    if ( !sercom->sendDataMasterWIRE( txBuffer.read_char() ) )
    {
      sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
      return 3 ;  // Nack or error
    }
  }
  
  if (stopBit)
  {
    sercom->prepareCommandBitsWire(WIRE_MASTER_ACT_STOP);
  }   

  return 0;
}

uint8_t TwoWire::endTransmission()
{
  return endTransmission(true);
}

size_t TwoWire::write(uint8_t ucData)
{
  // No writing, without begun transmission or a full buffer
  if ( !transmissionBegun || txBuffer.isFull() )
  {
    return 0 ;
  }

  txBuffer.store_char( ucData ) ;

  return 1 ;
}

size_t TwoWire::write(const uint8_t *data, size_t quantity)
{
  //Try to store all data
  for(size_t i = 0; i < quantity; ++i)
  {
    //Return the number of data stored, when the buffer is full (if write return 0)
    if(!write(data[i]))
      return i;
  }

  //All data stored
  return quantity;
}

int TwoWire::available(void)
{
  return rxBuffer.available();
}

int TwoWire::read(void)
{
  return rxBuffer.read_char();
}

int TwoWire::peek(void)
{
  return rxBuffer.peek();
}

void TwoWire::flush(void)
{
  // Do nothing, use endTransmission(..) to force
  // data transfer.
}

void TwoWire::onReceive(void(*function)(int))
{
  onReceiveCallback = function;
}

void TwoWire::onRequest(void(*function)(void))
{
  onRequestCallback = function;
}

void TwoWire::onService(void) {
	if (sercom->isSlaveWIRE()) {		
		if (sercom->isAddressMatch()) { 				// address match interrupt
			if (sercom->isMasterReadOperationWIRE()) {	// the master is making a read request
				sercom->prepareAckBitWIRE();
				sercom->prepareCommandBitsWire(0x03);
				
				txBuffer.clear();
				transmissionBegun = true;
				
				// call the onRequest callback to put bytes in the txBuffer
				if(onRequestCallback) {
					onRequestCallback();
				}
				
				while(!sercom->isStopDetectedWIRE()) { // write the bytes out to the master
					if (sercom->isDataReadyWIRE()) {
						uint8_t c = 0xff;
						if (txBuffer.available()) {
							c = txBuffer.read_char();
						}
						
						sercom->sendDataSlaveWIRE(c);
					}
				}
				
				// done sending bytes, NACK to shut things down
				sercom->prepareNackBitWIRE();
				sercom->prepareCommandBitsWire(0x03);

			} else if (!(sercom->isMasterReadOperationWIRE())) { // acknowledge master write request
				sercom->prepareAckBitWIRE();
				sercom->prepareCommandBitsWire(0x03);
				
				while(!(sercom->isStopDetectedWIRE() || sercom->isRestartDetectedWIRE())) { // read bytes from the master
					if(sercom->isDataReadyWIRE()) {
						if (rxBuffer.isFull()) {
							sercom->prepareNackBitWIRE();
							sercom->prepareCommandBitsWire(0x03);
							break;
						} else {
							rxBuffer.store_char(sercom->readDataWIRE());
							sercom->prepareAckBitWIRE();
							sercom->prepareCommandBitsWire(0x03);
						}
					}
				}
				
				if(sercom->isStopDetectedWIRE() || sercom->isRestartDetectedWIRE()) {
					if (onReceiveCallback) {
						onReceiveCallback(available());
					}

					rxBuffer.clear();
				}

				if(sercom->isStopDetectedWIRE()) {
					sercom->prepareNackBitWIRE();
					sercom->prepareCommandBitsWire(0x03);
				}

			} else {
				// do nothing
			}	
		} else {
			// do nothing
		}
	}
}

#if WIRE_INTERFACES_COUNT > 0
  /* In case new variant doesn't define these macros,
   * we put here the ones for Arduino Zero.
   *
   * These values should be different on some variants!
   */
  #ifndef PERIPH_WIRE
    #define PERIPH_WIRE          sercom3
    #define WIRE_IT_HANDLER      SERCOM3_Handler
  #endif // PERIPH_WIRE
  arduino::TwoWire Wire(&PERIPH_WIRE, PIN_WIRE_SDA, PIN_WIRE_SCL);

  void WIRE_IT_HANDLER(void) {
    Wire.onService();
  }
#endif

#if WIRE_INTERFACES_COUNT > 1
  arduino::TwoWire Wire1(&PERIPH_WIRE1, PIN_WIRE1_SDA, PIN_WIRE1_SCL);

  void WIRE1_IT_HANDLER(void) {
    Wire1.onService();
  }
#endif

#if WIRE_INTERFACES_COUNT > 2
  arduino::TwoWire Wire2(&PERIPH_WIRE2, PIN_WIRE2_SDA, PIN_WIRE2_SCL);

  void WIRE2_IT_HANDLER(void) {
    Wire2.onService();
  }
#endif

#if WIRE_INTERFACES_COUNT > 3
  arduino::TwoWire Wire3(&PERIPH_WIRE3, PIN_WIRE3_SDA, PIN_WIRE3_SCL);

  void WIRE3_IT_HANDLER(void) {
    Wire3.onService();
  }
#endif

#if WIRE_INTERFACES_COUNT > 4
  arduino::TwoWire Wire4(&PERIPH_WIRE4, PIN_WIRE4_SDA, PIN_WIRE4_SCL);

  void WIRE4_IT_HANDLER(void) {
    Wire4.onService();
  }
#endif

#if WIRE_INTERFACES_COUNT > 5
  arduino::TwoWire Wire5(&PERIPH_WIRE5, PIN_WIRE5_SDA, PIN_WIRE5_SCL);

  void WIRE5_IT_HANDLER(void) {
    Wire5.onService();
  }
#endif