APRSuino/src/main.cpp

#include <Arduino.h>
#include <util/crc16.h>

#include "afsk_sinus.hpp"

#define NCOMMENT 0
#define CALLSIGN "HB3YBQ"


uint8_t txdelay[32];

struct ax25 {
  uint8_t sflag;
  uint8_t daddr[7];
  uint8_t saddr[7];
  uint8_t ctrl;
  uint8_t proto;
  struct {
    uint8_t dtid;
    uint8_t type;
    char time[7];
    char lat[8];
    uint8_t sym_table_id;
    char lon[9];
    uint8_t sym_code;
    char comment[NCOMMENT];
  } __attribute__((packed)) aprs;
  uint16_t fcs;
  uint8_t eflag;
} __attribute__((packed)) frame;

enum AprsSymbol : uint8_t {
  NONE,
  AMBULANCE,
  BUS,
  FIRE_TRUCK,
  BICYCLE,
  YACHT,
  HELICOPTER,
  SMALL_AIRCRAFT,
  SHIP,
  CAR,
  MOTORCYCLE,
  BALLOON,
  JEEP,
  RECREATIONAL_VEHICLE,
  TRUCK,
  VAN
};


extern void sendOne(uint32_t *us, uint8_t *phaseShift);
extern void sendZero(uint32_t *us, uint8_t *phaseShift);
extern void setZero();

uint32_t m = 0;
uint8_t phaseShift = 0;
bool nrzi = true;

void sendBell202(uint8_t byt, bool sync) {
  if (sync) {
    phaseShift = 0;
    m = micros();
  }
  for (uint8_t i = 0; i < 8; ++i) {
    if (!((byt >> i) & 1)) {
      nrzi = !nrzi;
    }
    if (nrzi) {
      sendOne(&m, &phaseShift);
    } else {
      sendZero(&m, &phaseShift);
    }
  }
}

void sendBell202buf(uint8_t *buf, size_t len, bool sync) {
  for (size_t i = 0; i < len; ++i) {
    sendBell202(buf[i], sync);
    sync = false;
  }
}

void initFrame() {
  memset(txdelay, 0x7e, sizeof(txdelay));
  memset(&frame, 0, sizeof(frame));
  frame.sflag = 0x7e;
  memcpy(&frame.daddr, "GPS\x00\x00\x00\x00", 7);
  memcpy(&frame.saddr, CALLSIGN, 6);
  frame.ctrl = 0x03;
  frame.proto = 0xf0;
  frame.aprs.dtid = 1;
  memcpy(&frame.aprs.time, "151430h", 7);
  memcpy(&frame.aprs.lat, "4730.00N", 8);
  frame.aprs.sym_table_id = '/';
  memcpy(&frame.aprs.lon, "00730.00E", 9);
  frame.aprs.sym_code = BICYCLE;
  frame.fcs = 0xffff;
  for (size_t i = 0; i < sizeof(frame) - 3; ++i) {
    frame.fcs = _crc_xmodem_update(frame.fcs, ((uint8_t*) &frame)[i]);
  }
  frame.eflag = 0x7e;
}


void setup() {
  OUT_DDR = 0xff;
  setZero();
  initFrame();
  nrzi = true;
}

void loop() {
  sendBell202buf(txdelay, sizeof(txdelay), true);
  //sendBell202buf((uint8_t*) &frame, sizeof(frame) - 1, false);
  //sendBell202buf((uint8_t*) &frame, sizeof(frame) - 1, false);
  sendBell202buf((uint8_t*) &frame, sizeof(frame), false);
  setZero();
  nrzi = true;
  delay(10000);
}