CommandStation-EX/DCC.cpp

#include "DCC.h"
#include "DCCWaveform.h"
#include "DIAG.h"
#include "Hardware.h"

// This module is responsible for converting API calls into
// messages to be sent to the waveform generator.
// It has no visibility of the hardware, timers, interrupts
// nor of the waveform issues such as preambles, start bits checksums or cutouts.
//
// Nor should it have to deal with JMRI responsess other than the OK/FAIL
// or cv value returned. I will move that back to the JMRI interface later
//
// The interface to the waveform generator is narrowed down to merely:
//   Scheduling a message on the prog or main track using a function
//   Obtaining ACKs from the prog track using a function
//   There are no volatiles here.

void DCC::begin() {
  DCCWaveform::begin();
}

void DCC::setThrottle( uint16_t cab, uint8_t tSpeed, bool tDirection)  {
  byte speedCode = tSpeed + (tSpeed > 0) + tDirection * 128; // max speed is 126, but speed codes range from 2-127 (0=stop, 1=emergency stop)
  setThrottle2(cab, speedCode);
  // retain speed for loco reminders
  updateLocoReminder(cab, speedCode );
}

void DCC::setThrottle2( uint16_t cab, byte speedCode)  {

  uint8_t b[4];
  uint8_t nB = 0;

  if (cab > 127)
    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
  b[nB++] = lowByte(cab);
  b[nB++] = SET_SPEED;                      // 128-step speed control byte
  b[nB++] = speedCode; // for encoding see setThrottle

  DCCWaveform::mainTrack.schedulePacket(b, nB, 0);
}

void DCC::setFunction(int cab, byte byte1)  {
  uint8_t b[3];
  uint8_t nB = 0;

  if (cab > 127)
    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
  b[nB++] = lowByte(cab);
  b[nB++] = (byte1 | 0x80) & 0xBF;

  DCCWaveform::mainTrack.schedulePacket(b, nB, 4);     // Repeat the packet four times
}

void DCC::setFunction(int cab, byte byte1, byte byte2)  {
  byte b[4];
  byte nB = 0;

  if (cab > 127)
    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address
  b[nB++] = lowByte(cab);
  b[nB++] = (byte1 | 0xDE) & 0xDF;   // for safety this guarantees that first byte will either be 0xDE (for F13-F20) or 0xDF (for F21-F28)
  b[nB++] = byte2;

  DCCWaveform::mainTrack.schedulePacket(b, nB, 4);     // Repeat the packet four times
}

void DCC::setAccessory(int address, byte number, bool activate) {
  byte b[2];

  b[0] = address % 64 + 128;                                     // first byte is of the form 10AAAAAA, where AAAAAA represent 6 least signifcant bits of accessory address
  b[1] = ((((address / 64) % 8) << 4) + (number % 4 << 1) + activate % 2) ^ 0xF8; // second byte is of the form 1AAACDDD, where C should be 1, and the least significant D represent activate/deactivate

  DCCWaveform::mainTrack.schedulePacket(b, 2, 4);      // Repeat the packet four times
}

void DCC::writeCVByteMain(int cab, int cv, byte bValue)  {
  byte b[5];
  byte nB = 0;
  if (cab > 127)
    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address

  b[nB++] = lowByte(cab);
  b[nB++] = cv1(WRITE_BYTE_MAIN, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
  b[nB++] = cv2(cv);
  b[nB++] = bValue;

  DCCWaveform::mainTrack.schedulePacket(b, nB, 4);
}

void DCC::writeCVBitMain(int cab, int cv, byte bNum, bool bValue)  {
  byte b[5];
  byte nB = 0;
  bValue = bValue % 2;
  bNum = bNum % 8;

  if (cab > 127)
    b[nB++] = highByte(cab) | 0xC0;    // convert train number into a two-byte address

  b[nB++] = lowByte(cab);
  b[nB++] = cv1(WRITE_BIT_MAIN, cv); // any CV>1023 will become modulus(1024) due to bit-mask of 0x03
  b[nB++] = cv2(cv);
  b[nB++] = WRITE_BIT | (bValue ? BIT_ON : BIT_OFF) | bNum;

  DCCWaveform::mainTrack.schedulePacket(b, nB, 4);
}



const ackOp WRITE_BIT0_PROG[] = {
     BASELINE,
     W0,WACK,
     V0, WACK,  // validate bit is 0 
     ITC1,      // if acked, callback(1)
     FAIL  // callback (-1)
};
const ackOp WRITE_BIT1_PROG[] = {
     BASELINE,
     W1,WACK,
     V1, WACK,  // validate bit is 1 
     ITC1,      // if acked, callback(1)
     FAIL  // callback (-1)
};


const ackOp READ_BIT_PROG[] = {
     BASELINE,
     V1, WACK,  // validate bit is 1 
     ITC1,      // if acked, callback(1)
     V0, WACK,  // validate bit is zero
     ITC0,      // if acked callback 0
     FAIL       // bit not readable 
     };
     
const ackOp WRITE_BYTE_PROG[] = {
      BASELINE,
      WB,WACK,    // Write 
      VB,WACK,     // validate byte 
      ITC1,       // if ok callback (1)
      FAIL        // callback (-1)
      };
      
      
const ackOp READ_CV_PROG[] = {
      BASELINE,
      ZERO,    //clear bit and byte values
      // each bit is validated against 1 (no need for zero validation as entire byte is validated at the end)
      V1, WACK, MERGE,  // read and merge bit 0
      V1, WACK, MERGE,  // read and merge bit 1 etc
      V1, WACK, MERGE,
      V1, WACK, MERGE,
      V1, WACK, MERGE,
      V1, WACK, MERGE,
      V1, WACK, MERGE,
      V1, WACK, MERGE,
      VB, WACK, ITCB,  // verify merged byte and return it if acked ok 
      FAIL };          // verification failed



void  DCC::writeCVByte(int cv, byte byteValue, ACK_CALLBACK callback)  {
  ackManagerSetup(cv, byteValue,  WRITE_BYTE_PROG, callback);
}


void DCC::writeCVBit(int cv, byte bitNum, bool bitValue, ACK_CALLBACK callback)  {
  if (bitNum >= 8) callback(-1);
  else ackManagerSetup(cv, bitNum, bitValue?WRITE_BIT1_PROG:WRITE_BIT0_PROG, callback);
}


void DCC::readCVBit(int cv, byte bitNum, ACK_CALLBACK callback)  {
  if (bitNum >= 8) callback(-1);
  else ackManagerSetup(cv, bitNum,READ_BIT_PROG, callback);
}

void DCC::readCV(int cv, ACK_CALLBACK callback)  {
  ackManagerSetup(cv, 0,READ_CV_PROG, callback);
}


void DCC::loop()  {
  DCCWaveform::loop(); // power overload checks
  ackManagerLoop();
  // if the main track transmitter still has a pending packet, skip this loop.
  if ( DCCWaveform::mainTrack.packetPending) return;

  // each time around the Arduino loop, we resend a loco speed packet reminder
  for (; nextLoco < MAX_LOCOS; nextLoco++) {
    if (speedTable[nextLoco].loco > 0) {
      setThrottle2(speedTable[nextLoco].loco, speedTable[nextLoco].speedCode);
      nextLoco++;
      return;
    }
  }
  for (nextLoco = 0; nextLoco < MAX_LOCOS; nextLoco++) {
    if (speedTable[nextLoco].loco > 0) {
      setThrottle2(speedTable[nextLoco].loco, speedTable[nextLoco].speedCode);
      nextLoco++;
      return;
    }
  }
}

void DCC::getLocoId(ACK_CALLBACK callback) {
  callback(-1); // Not yet implemented 
//  
//  switch (readCVBit(29, 5)) {
//    case 1:
//      // long address : get CV#17 and CV#18
//      {
//        int cv17 = readCV(17);
//
//        if  (cv17 < 0) break;
//        int cv18 = readCV(18);
//        if  (cv18 < 0) break;
//        return cv18 + ((cv17 - 192) << 8);
//      }
//    case 0: // short address in CV1
//      return readCV(1);
//    default: // No response or loco
//      break;
//  }
//  return -1;
}

///// Private helper functions below here /////////////////////

byte DCC::cv1(byte opcode, int cv)  {
  cv--;
  return (highByte(cv) & (byte)0x03) | opcode;
}
byte DCC::cv2(int cv)  {
  cv--;
  return lowByte(cv);
}



void  DCC::updateLocoReminder(int loco, byte speedCode) {
  // determine speed reg for this loco
  int reg;
  int firstEmpty = MAX_LOCOS;
  for (reg = 0; reg < MAX_LOCOS; reg++) {
    if (speedTable[reg].loco == loco) break;
    if (speedTable[reg].loco == 0 && firstEmpty == MAX_LOCOS) firstEmpty = reg;
  }
  if (reg == MAX_LOCOS) reg = firstEmpty;
  if (reg >= MAX_LOCOS) {
    DIAG(F("\nToo many locos\n"));
    return;
  }
  speedTable[reg].loco = loco;
  speedTable[reg].speedCode = speedCode;
}

DCC::LOCO DCC::speedTable[MAX_LOCOS];
int DCC::nextLoco = 0;

//ACK MANAGER
ackOp  const *  DCC::ackManagerProg;
byte   DCC::ackManagerByte;
int   DCC::ackManagerCv;
byte   DCC::ackManagerBitNum;
bool   DCC::ackReceived;
int   DCC::ackTriggerMilliamps;

ACK_CALLBACK DCC::ackManagerCallback;

void  DCC::ackManagerSetup(int cv, byte byteValue, ackOp const program[], ACK_CALLBACK callback) {
  ackManagerCv = cv;
  ackManagerProg = program;
  ackManagerByte = byteValue;
  ackManagerCallback = callback;
  ackManagerBitNum=0;
}


void DCC::ackManagerLoop() {
  while (ackManagerProg) {

    // breaks from this switch will step to next prog entry
    // returns from this switch will stay on same entry (typically WACK waiting and when all finished.)
    byte opcode=*ackManagerProg;
    switch (opcode) {
      case W0:    // write bit 
      case W1:    // write bit 
            {
              byte instruction = WRITE_BIT | (opcode==W1 ? BIT_ON : BIT_OFF) | ackManagerByte;
              byte message[] = {cv1(BIT_MANIPULATE, ackManagerCv), cv2(ackManagerCv), instruction };
              DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 6);
            }
            break; 
      case WB:   // write byte 
            {
              byte message[] = {cv1(WRITE_BYTE, ackManagerCv), cv2(ackManagerCv), ackManagerByte};
              DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 6);
            }
            break;
      case   VB:     // Issue validate Byte packet
        {
          byte message[] = { cv1(VERIFY_BYTE, ackManagerCv), cv2(ackManagerCv), ackManagerByte};
          DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 5);
        }
        break;
      case V0:
      case V1:      // Issue validate bit=0 or bit=1  packet
        {
           byte instruction = VERIFY_BIT | (opcode==V0?BIT_OFF:BIT_ON) | ackManagerByte;
          byte message[] = {cv1(BIT_MANIPULATE, ackManagerCv), cv2(ackManagerCv), instruction };
          DCCWaveform::progTrack.schedulePacket(message, sizeof(message), 5);
        }
        break;
      case WACK:   // wait for ack (or absence of ack)
        if (DCCWaveform::progTrack.sentResetsSincePacket > 6) {
        ackReceived = false;
        break; // move on to next prog step
      }
      if (Hardware::getCurrentMilliamps(false) > ackTriggerMilliamps) {
        ackReceived = true;
        DCCWaveform::progTrack.killRemainingRepeats(); 
        break; // move on tho next step
      }
      return;  // maintain place for next poll cycle.

     case ITC0:
     case ITC1:   // If True Callback(0 or 1)  (if prevous WACK got an ACK)
        if (ackReceived) {
            ackManagerProg = NULL;
            (ackManagerCallback)(opcode==ITC0?0:1);
            return;
          }
        break;
      case ITCB:   // If True callback(byte)
          if (ackReceived) {
            ackManagerProg = NULL;
            (ackManagerCallback)(ackManagerByte);
            return;
          }
        break;
      case MERGE:  // Merge previous wack response with byte value and increment bit number (use for reading CV bytes)
          ackManagerByte <<= 1;
          if (ackReceived) ackManagerByte |= 1;
          ackManagerBitNum++;
          break;
      case FAIL:  // callback(-1)
           ackManagerProg = NULL;
           (ackManagerCallback)(-1);
           return;
      case ZERO:
           ackManagerBitNum=0;
           ackManagerByte=0;     
          break;
      case BASELINE:
           if (DCCWaveform::progTrack.sentResetsSincePacket < 6) return;  // try again later 
           ackTriggerMilliamps=Hardware::getCurrentMilliamps(false) + ACK_MIN_PULSE;
          break;
          }  // end of switch
    ackManagerProg++;
  }
}