Fix for Arduino DUE serial bug. https://github.com/firmata/arduino/issues/56#issuecomment-24014567

firmata.cpp

/*
  Firmata.cpp - Firmata library
  Copyright (C) 2006-2008 Hans-Christoph Steiner.  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.

  See file LICENSE.txt for further informations on licensing terms.
*/

//******************************************************************************
//* Includes
//******************************************************************************

#include "Firmata.h"
#include "HardwareSerial.h"

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

//******************************************************************************
//* Support Functions
//******************************************************************************

void FirmataClass::sendValueAsTwo7bitBytes(int value)
{
  FirmataSerial->write(value & B01111111); // LSB
  FirmataSerial->write(value >> 7 & B01111111); // MSB
}

void FirmataClass::startSysex(void)
{
  FirmataSerial->write(START_SYSEX);
}

void FirmataClass::endSysex(void)
{
  FirmataSerial->write(END_SYSEX);
}

//******************************************************************************
//* Constructors
//******************************************************************************

FirmataClass::FirmataClass()
{
  firmwareVersionCount = 0;
  firmwareVersionVector = 0;
  systemReset();
}

//******************************************************************************
//* Public Methods
//******************************************************************************

/* begin method with default serial bitrate */
void FirmataClass::begin(void)
{
  begin(57600);
}

/* begin method for overriding default serial bitrate */
void FirmataClass::begin(long speed)
{
  Serial.begin(speed);
  FirmataSerial = &Serial;
  blinkVersion();
  printVersion();
  printFirmwareVersion();

  // clear any garbage in the input stream (this fixes an issue with Due)
  while (FirmataSerial->read() != -1);
}

/* begin method for overriding default stream */
void FirmataClass::begin(Stream &s)
{
  FirmataSerial = &s;
  // do not call blinkVersion() here because some hardware such as the
  // Ethernet shield use pin 13
  delay(800); // required for issue with Due
  printVersion();
  printFirmwareVersion();
  // clear any garbage in the input stream (this fixes an issue with Due)
  while (FirmataSerial->read() != -1);
}

// output the protocol version message to the serial port
void FirmataClass::printVersion(void) {
  FirmataSerial->write(REPORT_VERSION);
  FirmataSerial->write(FIRMATA_MAJOR_VERSION);
  FirmataSerial->write(FIRMATA_MINOR_VERSION);
}

void FirmataClass::blinkVersion(void)
{
  // flash the pin with the protocol version
  pinMode(VERSION_BLINK_PIN,OUTPUT);
  strobeBlinkPin(FIRMATA_MAJOR_VERSION, 40, 210);
  delay(250);
  strobeBlinkPin(FIRMATA_MINOR_VERSION, 40, 210);
  delay(125);
}

void FirmataClass::printFirmwareVersion(void)
{
  byte i;

  if(firmwareVersionCount) { // make sure that the name has been set before reporting
    startSysex();
    FirmataSerial->write(REPORT_FIRMWARE);
    FirmataSerial->write(firmwareVersionVector[0]); // major version number
    FirmataSerial->write(firmwareVersionVector[1]); // minor version number
    for(i=2; i<firmwareVersionCount; ++i) {
      sendValueAsTwo7bitBytes(firmwareVersionVector[i]);
    }
    endSysex();
  }
}

void FirmataClass::setFirmwareNameAndVersion(const char *name, byte major, byte minor)
{
  const char *filename;
  char *extension;

  // parse out ".cpp" and "applet/" that comes from using __FILE__
  extension = strstr(name, ".cpp");
  filename = strrchr(name, '/') + 1; //points to slash, +1 gets to start of filename
  // add two bytes for version numbers
  if(extension && filename) {
    firmwareVersionCount = extension - filename + 2;
  } else {
    firmwareVersionCount = strlen(name) + 2;
    filename = name;
  }

  free(firmwareVersionVector);

  firmwareVersionVector = (byte *) malloc(firmwareVersionCount);
  firmwareVersionVector[firmwareVersionCount] = 0;
  firmwareVersionVector[0] = major;
  firmwareVersionVector[1] = minor;
  strncpy((char*)firmwareVersionVector + 2, filename, firmwareVersionCount - 2);
  // alas, no snprintf on Arduino
  //    snprintf(firmwareVersionVector, MAX_DATA_BYTES, "%c%c%s", 
  //             (char)major, (char)minor, firmwareVersionVector);
}

// this method is only used for unit testing
// void FirmataClass::unsetFirmwareVersion()
// {
//   firmwareVersionCount = 0;
//   free(firmwareVersionVector); 
//   firmwareVersionVector = 0;
// }
 
//------------------------------------------------------------------------------
// Serial Receive Handling

int FirmataClass::available(void)
{
  return FirmataSerial->available();
}


void FirmataClass::processSysexMessage(void)
{
  switch(storedInputData[0]) { //first byte in buffer is command
  case REPORT_FIRMWARE:
    printFirmwareVersion();
    break;
  case STRING_DATA:
    if(currentStringCallback) {
      byte bufferLength = (sysexBytesRead - 1) / 2;
      char *buffer = (char*)malloc(bufferLength * sizeof(char));
      byte i = 1;
      byte j = 0;
      while(j < bufferLength) {
        buffer[j] = (char)storedInputData[i];
        i++;
        buffer[j] += (char)(storedInputData[i] << 7);
        i++;
        j++;
      }
      (*currentStringCallback)(buffer);
    }
    break;
  default:
    if(currentSysexCallback)
      (*currentSysexCallback)(storedInputData[0], sysexBytesRead - 1, storedInputData + 1);
  }
}

void FirmataClass::processInput(void)
{
  int inputData = FirmataSerial->read(); // this is 'int' to handle -1 when no data
  int command;
    
  // TODO make sure it handles -1 properly
  
  if (parsingSysex) {
    if(inputData == END_SYSEX) {
      //stop sysex byte      
      parsingSysex = false;
      //fire off handler function
      processSysexMessage();
    } else {
      //normal data byte - add to buffer
      storedInputData[sysexBytesRead] = inputData;
      sysexBytesRead++;
    }
  } else if( (waitForData > 0) && (inputData < 128) ) {  
    waitForData--;
    storedInputData[waitForData] = inputData;
    if( (waitForData==0) && executeMultiByteCommand ) { // got the whole message
      switch(executeMultiByteCommand) {
      case ANALOG_MESSAGE:
        if(currentAnalogCallback) {
          (*currentAnalogCallback)(multiByteChannel,
                                   (storedInputData[0] << 7)
                                   + storedInputData[1]);
        }
        break;
      case DIGITAL_MESSAGE:
        if(currentDigitalCallback) {
          (*currentDigitalCallback)(multiByteChannel,
                                    (storedInputData[0] << 7)
                                    + storedInputData[1]);
        }
        break;
      case SET_PIN_MODE:
        if(currentPinModeCallback)
          (*currentPinModeCallback)(storedInputData[1], storedInputData[0]);
        break;
      case REPORT_ANALOG:
        if(currentReportAnalogCallback)
          (*currentReportAnalogCallback)(multiByteChannel,storedInputData[0]);
        break;
      case REPORT_DIGITAL:
        if(currentReportDigitalCallback)
          (*currentReportDigitalCallback)(multiByteChannel,storedInputData[0]);
        break;
      }
      executeMultiByteCommand = 0;
    }  
  } else {
    // remove channel info from command byte if less than 0xF0
    if(inputData < 0xF0) {
      command = inputData & 0xF0;
      multiByteChannel = inputData & 0x0F;
    } else {
      command = inputData;
      // commands in the 0xF* range don't use channel data
    }
    switch (command) {
    case ANALOG_MESSAGE:
    case DIGITAL_MESSAGE:
    case SET_PIN_MODE:
      waitForData = 2; // two data bytes needed
      executeMultiByteCommand = command;
      break;
    case REPORT_ANALOG:
    case REPORT_DIGITAL:
      waitForData = 1; // two data bytes needed
      executeMultiByteCommand = command;
      break;
    case START_SYSEX:
      parsingSysex = true;
      sysexBytesRead = 0;
      break;
    case SYSTEM_RESET:
      systemReset();
      break;
    case REPORT_VERSION:
      Firmata.printVersion();
      break;
    }
  }
}

//------------------------------------------------------------------------------
// Serial Send Handling

// send an analog message
void FirmataClass::sendAnalog(byte pin, int value) 
{
  // pin can only be 0-15, so chop higher bits
  FirmataSerial->write(ANALOG_MESSAGE | (pin & 0xF));
  sendValueAsTwo7bitBytes(value);
}

// send a single digital pin in a digital message
void FirmataClass::sendDigital(byte pin, int value) 
{
  /* TODO add single pin digital messages to the protocol, this needs to
   * track the last digital data sent so that it can be sure to change just
   * one bit in the packet.  This is complicated by the fact that the
   * numbering of the pins will probably differ on Arduino, Wiring, and
   * other boards.  The DIGITAL_MESSAGE sends 14 bits at a time, but it is
   * probably easier to send 8 bit ports for any board with more than 14
   * digital pins.
   */

  // TODO: the digital message should not be sent on the serial port every
  // time sendDigital() is called.  Instead, it should add it to an int
  // which will be sent on a schedule.  If a pin changes more than once
  // before the digital message is sent on the serial port, it should send a
  // digital message for each change.

  //    if(value == 0)
  //        sendDigitalPortPair();
}


// send 14-bits in a single digital message (protocol v1)
// send an 8-bit port in a single digital message (protocol v2)
void FirmataClass::sendDigitalPort(byte portNumber, int portData)
{
  FirmataSerial->write(DIGITAL_MESSAGE | (portNumber & 0xF));
  FirmataSerial->write((byte)portData % 128); // Tx bits 0-6
  FirmataSerial->write(portData >> 7);  // Tx bits 7-13
}


void FirmataClass::sendSysex(byte command, byte bytec, byte* bytev) 
{
  byte i;
  startSysex();
  FirmataSerial->write(command);
  for(i=0; i<bytec; i++) {
    sendValueAsTwo7bitBytes(bytev[i]);        
  }
  endSysex();
}

void FirmataClass::sendString(byte command, const char* string) 
{
  sendSysex(command, strlen(string), (byte *)string);
}


// send a string as the protocol string type
void FirmataClass::sendString(const char* string) 
{
  sendString(STRING_DATA, string);
}

// expose the write method
void FirmataClass::write(byte c)
{
  FirmataSerial->write(c);
}


// Internal Actions/////////////////////////////////////////////////////////////

// generic callbacks
void FirmataClass::attach(byte command, callbackFunction newFunction)
{
  switch(command) {
  case ANALOG_MESSAGE: currentAnalogCallback = newFunction; break;
  case DIGITAL_MESSAGE: currentDigitalCallback = newFunction; break;
  case REPORT_ANALOG: currentReportAnalogCallback = newFunction; break;
  case REPORT_DIGITAL: currentReportDigitalCallback = newFunction; break;
  case SET_PIN_MODE: currentPinModeCallback = newFunction; break;
  }
}

void FirmataClass::attach(byte command, systemResetCallbackFunction newFunction)
{
  switch(command) {
  case SYSTEM_RESET: currentSystemResetCallback = newFunction; break;
  }
}

void FirmataClass::attach(byte command, stringCallbackFunction newFunction)
{
  switch(command) {
  case STRING_DATA: currentStringCallback = newFunction; break;
  }
}

void FirmataClass::attach(byte command, sysexCallbackFunction newFunction)
{
  currentSysexCallback = newFunction;
}

void FirmataClass::detach(byte command)
{
  switch(command) {
  case SYSTEM_RESET: currentSystemResetCallback = NULL; break;
  case STRING_DATA: currentStringCallback = NULL; break;
  case START_SYSEX: currentSysexCallback = NULL; break;
  default:
    attach(command, (callbackFunction)NULL);
  }
}

// sysex callbacks
/*
 * this is too complicated for analogReceive, but maybe for Sysex?
 void FirmataClass::attachSysex(sysexFunction newFunction)
 {
 byte i;
 byte tmpCount = analogReceiveFunctionCount;
 analogReceiveFunction* tmpArray = analogReceiveFunctionArray;
 analogReceiveFunctionCount++;
 analogReceiveFunctionArray = (analogReceiveFunction*) calloc(analogReceiveFunctionCount, sizeof(analogReceiveFunction));
 for(i = 0; i < tmpCount; i++) {
 analogReceiveFunctionArray[i] = tmpArray[i];
 }
 analogReceiveFunctionArray[tmpCount] = newFunction;
 free(tmpArray);
 }
*/

//******************************************************************************
//* Private Methods
//******************************************************************************



// resets the system state upon a SYSTEM_RESET message from the host software
void FirmataClass::systemReset(void)
{
  byte i;

  waitForData = 0; // this flag says the next serial input will be data
  executeMultiByteCommand = 0; // execute this after getting multi-byte data
  multiByteChannel = 0; // channel data for multiByteCommands

  for(i=0; i<MAX_DATA_BYTES; i++) {
    storedInputData[i] = 0;
  }

  parsingSysex = false;
  sysexBytesRead = 0;

  if(currentSystemResetCallback)
    (*currentSystemResetCallback)();

  //flush(); //TODO uncomment when Firmata is a subclass of HardwareSerial
}



// =============================================================================
// used for flashing the pin for the version number
void FirmataClass::strobeBlinkPin(int count, int onInterval, int offInterval) 
{
  byte i;
  pinMode(VERSION_BLINK_PIN, OUTPUT);
  for(i=0; i<count; i++) {
    delay(offInterval);
    digitalWrite(VERSION_BLINK_PIN, HIGH);
    delay(onInterval);
    digitalWrite(VERSION_BLINK_PIN, LOW);
  }
}


// make one instance for the user to use
FirmataClass Firmata;