OneWireArduinoSlaveATTINY85/OneWireSlave.cpp

#include "OneWireSlave.h"

// uncomment this line to enable sending messages along with errors (but takes more program memory)
//#define ERROR_MESSAGES

#ifdef ERROR_MESSAGES
#define ERROR(msg) error_(msg)
#else
#define ERROR(msg) error_(0)
#endif

namespace
{
#if defined (__AVR_ATtiny85__)

const unsigned long ResetMinDuration = 480;      // min 480us  / 484us measured
const unsigned long ResetMaxDuration = 640;      //

const unsigned long PresenceWaitDuration = 35;   //  spec 15us to 60us  / 40us measured

const unsigned long PresenceDuration = 150;      //   spec  60us to 240us  / 148us measured

const unsigned long ReadBitSamplingTime = 15;    //   spec > 15us to 60us  / 31us measured

// SendBitDuration varies the bus release time to indicate a "1"
// measured total send bit duration is 63us versus 60us in the spec
const unsigned long SendBitDuration = 20;   // bus release time spec 15us / measured 19us


#elif defined (__AVR_ATmega328P__)

const unsigned long ResetMinDuration = 480;
const unsigned long ResetMaxDuration = 900;

const unsigned long PresenceWaitDuration = 15;

const unsigned long PresenceDuration = 200;

const unsigned long ReadBitSamplingTime = 25;

const unsigned long SendBitDuration = 35;

#endif

const byte ReceiveCommand = (byte) - 1;

void(*timerEvent)() = 0;
}

OneWireSlave OWSlave;

byte OneWireSlave::rom_[8];
byte OneWireSlave::scratchpad_[8];
Pin OneWireSlave::pin_;

unsigned long OneWireSlave::resetStart_;
unsigned long OneWireSlave::lastReset_;

void(*OneWireSlave::receiveBitCallback_)(bool bit, bool error);
void(*OneWireSlave::bitSentCallback_)(bool error);
void(*OneWireSlave::clientReceiveCallback_)(ReceiveEvent evt, byte data);
void(*OneWireSlave::clientReceiveBitCallback_)(bool bit);

byte OneWireSlave::receivingByte_;

byte OneWireSlave::searchRomBytePos_;
byte OneWireSlave::searchRomBitPos_;
bool OneWireSlave::searchRomInverse_;
bool OneWireSlave::resumeCommandFlag_;
bool OneWireSlave::alarmedFlag_;

const byte* OneWireSlave::sendBuffer_;
byte* OneWireSlave::recvBuffer_;
short OneWireSlave::bufferLength_;
byte OneWireSlave::bufferBitPos_;
short OneWireSlave::bufferPos_;
void(*OneWireSlave::receiveBytesCallback_)(bool error);
void(*OneWireSlave::sendBytesCallback_)(bool error);

volatile bool OneWireSlave::waitingSynchronousWriteToComplete_;
volatile bool OneWireSlave::synchronousWriteError_;

bool OneWireSlave::sendingClientBytes_;

bool OneWireSlave::singleBit_;
bool OneWireSlave::singleBitRepeat_;
void(*OneWireSlave::singleBitSentCallback_)(bool error);

void(*OneWireSlave::logCallback_)(const char* message);


ISR(USERTIMER_COMPA_vect) // timer1 interrupt
{
  UserTimer_Stop(); // disable clock
  void(*event)() = timerEvent;
  timerEvent = 0;
  event();
}

void OneWireSlave::begin(const byte* rom, byte pinNumber)
{
  pin_ = Pin(pinNumber);
  resetStart_ = (unsigned long) - 1;
  lastReset_ = 0;

  memcpy(rom_, rom, 7);
  rom_[7] = crc8(rom_, 7);

  resumeCommandFlag_ = false;
  alarmedFlag_       = false;

  clientReceiveBitCallback_ = 0;
  sendingClientBytes_ = false;

  // log("Enabling 1-wire library")

  cli(); // disable interrupts
  pin_.inputMode();
  pin_.writeLow(); // make sure the internal pull-up resistor is disabled

  // prepare hardware timer
  UserTimer_Init();

  // start 1-wire activity
  beginWaitReset_();
  sei(); // enable interrupts
}

void OneWireSlave::end()
{
  // log("Disabling 1-wire library");

  cli();
  disableTimer_();
  pin_.detachInterrupt();
  releaseBus_();
  sei();
}

bool OneWireSlave::write(const byte* bytes, short numBytes)
{
  // TODO: put the arduino to sleep between interrupts to save power?
  waitingSynchronousWriteToComplete_ = true;
  beginWrite(bytes, numBytes, &OneWireSlave::onSynchronousWriteComplete_);
  while (waitingSynchronousWriteToComplete_)
    delay(1);
  return !synchronousWriteError_;
}

void OneWireSlave::onSynchronousWriteComplete_(bool error)
{
  synchronousWriteError_ = error;
  waitingSynchronousWriteToComplete_ = false;
}

void OneWireSlave::beginWrite(const byte* bytes, short numBytes, void(*complete)(bool error))
{
  cli();
  endWrite_(true);
  sendingClientBytes_ = true;
  beginWriteBytes_(bytes, numBytes, complete == 0 ? noOpCallback_ : complete);
  sei();
}

void OneWireSlave::endWrite_(bool error, bool resetInterrupts)
{
  if (resetInterrupts)
    beginWaitReset_();

  if (sendingClientBytes_)
  {
    sendingClientBytes_ = false;
    if (sendBytesCallback_ != 0)
    {
      void(*callback)(bool error) = sendBytesCallback_;
      sendBytesCallback_ = noOpCallback_;
      callback(error);
    }
  }
  else if (singleBitSentCallback_ != 0)
  {
    void(*callback)(bool) = singleBitSentCallback_;
    singleBitSentCallback_ = 0;
    callback(error);
  }
}

bool OneWireSlave::writeBit(bool value)
{
  // TODO: put the arduino to sleep between interrupts to save power?
  waitingSynchronousWriteToComplete_ = true;
  beginWriteBit(value, false, &OneWireSlave::onSynchronousWriteComplete_);
  while (waitingSynchronousWriteToComplete_)
    delay(1);
  return !synchronousWriteError_;
}

void OneWireSlave::beginWriteBit(bool value, bool repeat, void(*bitSent)(bool))
{
  cli();
  endWrite_(true);

  singleBit_ = value;
  singleBitRepeat_ = repeat;
  singleBitSentCallback_ = bitSent;
  beginSendBit_(value, &OneWireSlave::onSingleBitSent_);
  sei();
}

void OneWireSlave::onSingleBitSent_(bool error)
{
  if (!error && singleBitRepeat_)
  {
    beginSendBit_(singleBit_, &OneWireSlave::onSingleBitSent_);
  }
  else
  {
    beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
  }

  if (singleBitSentCallback_ != 0)
  {
    void(*callback)(bool) = singleBitSentCallback_;
    singleBitSentCallback_ = 0;
    callback(error);
  }
}

void OneWireSlave::stopWrite()
{
  beginWrite(0, 0, 0);
}

void OneWireSlave::alarmed(bool value)
{
  alarmedFlag_ = value;
}

byte OneWireSlave::crc8(const byte* data, short numBytes)
{
  byte crc = 0;

  while (numBytes--) {
    byte inbyte = *data++;
    for (byte i = 8; i; i--) {
      byte mix = (crc ^ inbyte) & 0x01;
      crc >>= 1;
      if (mix) crc ^= 0x8C;
      inbyte >>= 1;
    }
  }
  return crc;
}

#if defined (__AVR_ATtiny85__)

void OneWireSlave::setTimerEvent_(short delayMicroSeconds, void(*handler)())
{
  delayMicroSeconds -= 8; // remove overhead (tuned on attiny85, values 0 - 10 work ok)

  short skipTicks = delayMicroSeconds / 2; // 16mhz clock, prescaler = 32
  if (skipTicks < 1) skipTicks = 1;
  timerEvent = handler;
  UserTimer_Run(skipTicks);
}

#elif defined (__AVR_ATmega328P__)

void OneWireSlave::setTimerEvent_(short delayMicroSeconds, void(*handler)())
{
  delayMicroSeconds -= 10; // remove overhead (tuned on Arduino Uno)

  // prescaler 64
  short skipTicks = (delayMicroSeconds - 3) / 4; // round the micro seconds delay to a number of ticks to skip (4us per tick, so 4us must skip 0 tick, 8us must skip 1 tick, etc.)
  if (skipTicks < 1) skipTicks = 1;
  timerEvent = handler;
  UserTimer_Run(skipTicks);
}

#endif

void OneWireSlave::disableTimer_()
{
  UserTimer_Stop();
}

void OneWireSlave::onEnterInterrupt_()
{
}

void OneWireSlave::onLeaveInterrupt_()
{
}

void OneWireSlave::error_(const char* message)
{
  if (logCallback_ != 0)
    logCallback_(message);
  endWrite_(true);
  if (clientReceiveCallback_ != 0)
    clientReceiveCallback_(RE_Error, 0);
}

void OneWireSlave::pullLow_()
{
  pin_.outputMode();
  pin_.writeLow();
}

void OneWireSlave::releaseBus_()
{
  pin_.inputMode();
}

void OneWireSlave::beginResetDetection_()
{
  setTimerEvent_(ResetMinDuration - 50, &OneWireSlave::resetCheck_);
  resetStart_ = micros() - 50;
}

void OneWireSlave::beginResetDetectionSendZero_()
{
  setTimerEvent_(ResetMinDuration - SendBitDuration - 50, &OneWireSlave::resetCheck_);
  resetStart_ = micros() - SendBitDuration - 50;
}

void OneWireSlave::cancelResetDetection_()
{
  disableTimer_();
  resetStart_ = (unsigned long) - 1;
}

void OneWireSlave::resetCheck_()
{
  onEnterInterrupt_();
  if (!pin_.read())
  {
    pin_.attachInterrupt(&OneWireSlave::waitReset_, CHANGE);
    // log("Reset detected during another operation");
  }
  onLeaveInterrupt_();
}

void OneWireSlave::beginReceiveBit_(void(*completeCallback)(bool bit, bool error))
{
  receiveBitCallback_ = completeCallback;
  pin_.attachInterrupt(&OneWireSlave::receive_, FALLING);
}

void OneWireSlave::receive_()
{
  onEnterInterrupt_();

  pin_.detachInterrupt();
  setTimerEvent_(ReadBitSamplingTime, &OneWireSlave::readBit_);

  onLeaveInterrupt_();
}

void OneWireSlave::readBit_()
{
  onEnterInterrupt_();

  bool bit = pin_.read();
  if (bit)
    cancelResetDetection_();
  else
    beginResetDetection_();
  receiveBitCallback_(bit, false);
  //dbgOutput.writeLow();
  //dbgOutput.writeHigh();

  onLeaveInterrupt_();
}

void OneWireSlave::beginSendBit_(bool bit, void(*completeCallback)(bool error))
{
  bitSentCallback_ = completeCallback;
  if (bit)
  {
    pin_.attachInterrupt(&OneWireSlave::sendBitOne_, FALLING);
  }
  else
  {
    pin_.attachInterrupt(&OneWireSlave::sendBitZero_, FALLING);
  }
}

void OneWireSlave::sendBitOne_()
{
  onEnterInterrupt_();

  beginResetDetection_();
  bitSentCallback_(false);

  onLeaveInterrupt_();
}

void OneWireSlave::sendBitZero_()
{
  pullLow_(); // this must be executed first because the timing is very tight with some master devices

  onEnterInterrupt_();

  pin_.detachInterrupt();
  setTimerEvent_(SendBitDuration, &OneWireSlave::endSendBitZero_);

  onLeaveInterrupt_();
}

void OneWireSlave::endSendBitZero_()
{
  onEnterInterrupt_();

  releaseBus_();
  beginResetDetectionSendZero_();
  bitSentCallback_(false);

  onLeaveInterrupt_();
}

void OneWireSlave::beginWaitReset_()
{
  disableTimer_();
  pin_.inputMode();
  pin_.attachInterrupt(&OneWireSlave::waitReset_, CHANGE);
  //resetStart_ = (unsigned int) - 1;
  resetStart_ = (unsigned long) - 1;
}


void OneWireSlave::waitReset_()
{
  onEnterInterrupt_();
  bool state = pin_.read();
  unsigned long now = micros();
  if (state)
  {
    if (resetStart_ == (unsigned long) - 1)
    {
      onLeaveInterrupt_();
      return;
    }
    static unsigned long resetDuration = now - resetStart_;
    //resetStart_ = (unsigned int) - 1;
    resetStart_ = (unsigned long) - 1;
    if (resetDuration >= ResetMinDuration)
    {

     // The following test has been removed because of a bug which causes the value of 
     // resetduration to exceed ResetMaxDuration intermittently. This happens
     // only on the attiny platform - possibly due to the implementation of
     // micros() in the attiny core 
     
     // if (resetDuration > ResetMaxDuration)
     // {
     //  ERROR("Reset too long");
     //   onLeaveInterrupt_();
     //   return;
     // }

      lastReset_ = now;
      pin_.detachInterrupt();
      unsigned long alreadyElapsedTime = micros() - now;
      setTimerEvent_(alreadyElapsedTime < PresenceWaitDuration ? PresenceWaitDuration - alreadyElapsedTime : 0, &OneWireSlave::beginPresence_);
      endWrite_(true, false);
      if (clientReceiveCallback_ != 0)
        clientReceiveCallback_(RE_Reset, 0);
    } else
    {
      //ERROR("Reset too short");
    }
  }
  else
  {
    resetStart_ = now;
  }
  onLeaveInterrupt_();
}

void OneWireSlave::beginPresence_()
{
  pullLow_();
  setTimerEvent_(PresenceDuration, &OneWireSlave::endPresence_);
}

void OneWireSlave::endPresence_()
{
  releaseBus_();

  beginWaitCommand_();
}

void OneWireSlave::beginWaitCommand_()
{
  bufferPos_ = ReceiveCommand;
  beginReceive_();
}

void OneWireSlave::beginReceive_()
{
  receivingByte_ = 0;
  bufferBitPos_ = 0;
  beginReceiveBit_(&OneWireSlave::onBitReceived_);
}

void OneWireSlave::onBitReceived_(bool bit, bool error)
{
  if (error)
  {
    ERROR("Invalid bit");
    if (bufferPos_ >= 0)
      receiveBytesCallback_(true);
    return;
  }

   receivingByte_ |= ((bit ? 1 : 0) << bufferBitPos_);
  ++bufferBitPos_;

  if (clientReceiveBitCallback_ != 0 && bufferPos_ != ReceiveCommand)
    clientReceiveBitCallback_(bit);

  if (bufferBitPos_ == 8)
  {
    // log("received byte", (long)receivingByte_);

    if (bufferPos_ == ReceiveCommand)
    {
      bufferPos_ = 0;
      switch (receivingByte_)
      {
        case 0xF0: // SEARCH ROM
          resumeCommandFlag_ = false;
          beginSearchRom_();
          return;
        case 0xEC: // CONDITIONAL SEARCH ROM
          resumeCommandFlag_ = false;
          if (alarmedFlag_)
          {
            beginSearchRom_();
          }
          else
          {
            beginWaitReset_();
          }
          return;
        case 0x33: // READ ROM
          resumeCommandFlag_ = false;
          beginWriteBytes_(rom_, 8, &OneWireSlave::noOpCallback_);
          return;
        case 0x55: // MATCH ROM
          resumeCommandFlag_ = false;
          beginReceiveBytes_(scratchpad_, 8, &OneWireSlave::matchRomBytesReceived_);
          return;
        case 0xCC: // SKIP ROM
          resumeCommandFlag_ = false;
          beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
          return;
        case 0xA5: // RESUME
          if (resumeCommandFlag_)
          {
            beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
          }
          else
          {
            beginWaitReset_();
          }
          return;
        default:
          ERROR("Unknown command");
          return;
      }
    }
    else
    {
      recvBuffer_[bufferPos_++] = receivingByte_;
      receivingByte_ = 0;
      bufferBitPos_ = 0;
      if (bufferPos_ == bufferLength_)
      {
        beginWaitReset_();
        receiveBytesCallback_(false);
        return;
      }
    }
  }

  beginReceiveBit_(&OneWireSlave::onBitReceived_);
}

void OneWireSlave::beginSearchRom_()
{
  searchRomBytePos_ = 0;
  searchRomBitPos_ = 0;
  searchRomInverse_ = false;

  beginSearchRomSendBit_();
}

void OneWireSlave::beginSearchRomSendBit_()
{
  byte currentByte = rom_[searchRomBytePos_];
  bool currentBit = bitRead(currentByte, searchRomBitPos_);
  bool bitToSend = searchRomInverse_ ? !currentBit : currentBit;

  beginSendBit_(bitToSend, &OneWireSlave::continueSearchRom_);
}

void OneWireSlave::continueSearchRom_(bool error)
{
  if (error)
  {
    ERROR("Failed to send bit");
    return;
  }

  searchRomInverse_ = !searchRomInverse_;
  if (searchRomInverse_)
  {
    beginSearchRomSendBit_();
  }
  else
  {
    beginReceiveBit_(&OneWireSlave::searchRomOnBitReceived_);
  }
}

void OneWireSlave::searchRomOnBitReceived_(bool bit, bool error)
{
  if (error)
  {
    ERROR("Bit read error during ROM search");
    return;
  }

  byte currentByte = rom_[searchRomBytePos_];
  bool currentBit = bitRead(currentByte, searchRomBitPos_);

  if (bit == currentBit)
  {
    ++searchRomBitPos_;
    if (searchRomBitPos_ == 8)
    {
      searchRomBitPos_ = 0;
      ++searchRomBytePos_;
    }

    if (searchRomBytePos_ == 8)
    {
      // log("ROM sent entirely");

      beginWaitReset_();
    }
    else
    {
      beginSearchRomSendBit_();
    }
  }
  else
  {
    // log("Leaving ROM search");
    beginWaitReset_();
  }
}

void OneWireSlave::beginWriteBytes_(const byte * data, short numBytes, void(*complete)(bool error))
{
  sendBuffer_ = data;
  bufferLength_ = numBytes;
  bufferPos_ = 0;
  bufferBitPos_ = 0;
  sendBytesCallback_ = complete;

  if (sendBuffer_ != 0 && bufferLength_ > 0)
  {
    bool bit = bitRead(sendBuffer_[0], 0);
    beginSendBit_(bit, &OneWireSlave::bitSent_);
  }
  else
  {
    endWrite_(true);
    beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
  }
}

void OneWireSlave::bitSent_(bool error)
{
  if (error)
  {
    ERROR("error sending a bit");
    sendBytesCallback_(true);
    return;
  }

  ++bufferBitPos_;
  if (bufferBitPos_ == 8)
  {
    bufferBitPos_ = 0;
    ++bufferPos_;
  }

  if (bufferPos_ == bufferLength_)
  {
    endWrite_(false);
    sendBytesCallback_(false);
    return;
  }

  bool bit = bitRead(sendBuffer_[bufferPos_], bufferBitPos_);
  beginSendBit_(bit, &OneWireSlave::bitSent_);
}

void OneWireSlave::beginReceiveBytes_(byte * buffer, short numBytes, void(*complete)(bool error))
{
  recvBuffer_ = buffer;
  bufferLength_ = numBytes;
  bufferPos_ = 0;
  receiveBytesCallback_ = complete;
  beginReceive_();
}

void OneWireSlave::noOpCallback_(bool error)
{
  if (error)
    ERROR("error during an internal 1-wire operation");
}

void OneWireSlave::matchRomBytesReceived_(bool error)
{
  if (error)
  {
    resumeCommandFlag_ = false;
    ERROR("error receiving match rom bytes");
    return;
  }

  if (memcmp(rom_, scratchpad_, 8) == 0)
  {
    // log("ROM matched");
    resumeCommandFlag_ = true;
    beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
  }
  else
  {
    // log("ROM not matched");
    resumeCommandFlag_ = false;
    beginWaitReset_();
  }
}

void OneWireSlave::notifyClientByteReceived_(bool error)
{
  if (error)
  {
    if (clientReceiveCallback_ != 0)
      clientReceiveCallback_(RE_Error, 0);
    ERROR("error receiving custom bytes");
    return;
  }

  beginReceiveBytes_(scratchpad_, 1, &OneWireSlave::notifyClientByteReceived_);
  if (clientReceiveCallback_ != 0)
    clientReceiveCallback_(RE_Byte, scratchpad_[0]);
}