CommandStation-EX/DCCWaveform.h

const int  POWER_SAMPLE_MAX = 300;
const int  POWER_SAMPLE_ON_WAIT = 100;
const int  POWER_SAMPLE_OFF_WAIT = 1000;
const int  POWER_SAMPLE_OVERLOAD_WAIT = 4000;


// ACK current analogRead values (vary depending on motor shield and cpu voltage)
const int   ACK_BASELINE_SAMPLES = 250 ;  // current samples before sending ACKable request
const int   ACK_TIMEOUT = 25 ;  // millis getAck is prepared to wait for a signal
const int   ACK_MIN_PULSE = 60 ;   // current above baseline which a pulse is recognised

const int   PREAMBLE_BITS_MAIN = 20;
const int   PREAMBLE_BITS_PROG = 22;

// Railcom settings
const bool RAILCOM_CUTOUT = true;
const byte RAILCOM_PREAMBLES_BEFORE_CUTOUT = 1; // how far into the preamble do we cutout



const byte   MAX_PACKET_SIZE = 12;
// NOTE: static functions are used for the overall controller, then
// one instance is created for each track.


enum class POWERMODE { OFF, ON, OVERLOAD };

const byte idlePacket[] = {0xFF, 0x00, 0xFF};
const byte resetPacket[] = {0x00, 0x00, 0x00};

class DCCWaveform {
  public:
    DCCWaveform( byte preambleBits, bool isMain);
    static void begin();
    static void loop();
    static DCCWaveform  mainTrack;
    static DCCWaveform  progTrack;

    void beginTrack();
    void setPowerMode(POWERMODE);
    POWERMODE getPowerMode();
    void checkPowerOverload();
    void schedulePacket(const byte buffer[], byte byteCount, byte repeats);
    bool schedulePacketWithAck(const byte buffer[], byte byteCount, byte repeats);
    volatile bool packetPending;


  private:

    static void interruptHandler();
    bool interrupt1();
    void interrupt2();

    bool isMainTrack;

    // Transmission controller
    byte transmitPacket[MAX_PACKET_SIZE];  // packet being transmitted
    byte transmitLength;
    byte transmitRepeats;      // remaining repeats of transmission
    byte remainingPreambles;
    byte requiredPreambles;
    bool currentBit;           // bit to be transmitted
    byte bits_sent;           // 0-8 (yes 9 bits) sent for current byte
    byte bytes_sent;          // number of bytes sent from transmitPacket
    byte state;               // wave generator state machine
    void checkRailcom();

    byte pendingPacket[MAX_PACKET_SIZE];
    byte pendingLength;
    byte pendingRepeats;

    
    // current sampling
    POWERMODE powerMode;
    unsigned long nextSampleDue;
};