ESP32-PaxCounter/src/timekeeper.cpp

#include "timekeeper.h"

#if !(HAS_LORA)
#if (TIME_SYNC_LORASERVER)
#error TIME_SYNC_LORASERVER defined, but device has no LORA configured
#elif (TIME_SYNC_LORAWAN)
#error TIME_SYNC_LORAWAN defined, but device has no LORA configured
#endif
#endif

#if (defined HAS_DCF77 && defined HAS_IF482)
#error You must define at most one of IF482 or DCF77!
#endif

// Local logging tag
static const char TAG[] = __FILE__;

// symbol to display current time source
// G = GPS / R = RTC / L = LORA / * = no sync / ? = never synced
const char timeSetSymbols[] = {'G', 'R', 'L', '*', '?'};

bool volatile TimePulseTick = false;
timesource_t timeSource = _unsynced;
TaskHandle_t ClockTask = NULL;
hw_timer_t *ppsIRQ = NULL;

#ifdef HAS_IF482
HardwareSerial IF482(2); // use UART #2 (#1 may be in use for serial GPS)
static TickType_t txDelay = pdMS_TO_TICKS(1000 - IF482_SYNC_FIXUP) -
                            tx_Ticks(IF482_FRAME_SIZE, HAS_IF482);
#if (HAS_SDS011)
#error cannot use IF482 together with SDS011 (both use UART#2)
#endif

#endif // HAS_IF482

Ticker timesyncer;

void setTimeSyncIRQ() { xTaskNotify(irqHandlerTask, TIMESYNC_IRQ, eSetBits); }

void calibrateTime(void) {

  time_t t = 0;
  uint16_t t_msec = 0;

  // kick off asychronous lora timesync if we have
#if (HAS_LORA) && ((TIME_SYNC_LORASERVER) || (TIME_SYNC_LORAWAN))
  timesync_request();
#endif

  // if no LORA timesource is available, or if we lost time, then fallback to
  // local time source RTS or GPS
  if (((!TIME_SYNC_LORASERVER) && (!TIME_SYNC_LORAWAN)) ||
      (timeSource == _unsynced)) {

// has RTC -> fallback to RTC time
#ifdef HAS_RTC
    t = get_rtctime(&t_msec);
    // set time from RTC - method will check if time is valid
    setMyTime((uint32_t)t, t_msec, _rtc);
#endif

// no RTC -> fallback to GPS time
#if (HAS_GPS)
    t = get_gpstime(&t_msec);
    // set time from GPS - method will check if time is valid
    setMyTime((uint32_t)t, t_msec, _gps);
#endif

  } // fallback

  else

    // no fallback time source available -> we can't set time
    return;

} // calibrateTime()

// set system time (UTC), calibrate RTC and RTC_INT pps
void IRAM_ATTR setMyTime(uint32_t t_sec, uint16_t t_msec,
                         timesource_t mytimesource) {

  struct timeval tv = {0};

  // called with invalid timesource?
  if (mytimesource == _unsynced)
    return;

  // increment t_sec if t_msec > 1000
  time_t time_to_set = (time_t)(t_sec + t_msec / 1000);

  // do we have a valid time?
  if (timeIsValid(time_to_set)) {

    // if we have msec fraction, then wait until top of second with
    // millisecond precision
    if (t_msec % 1000) {
      time_to_set++;
      vTaskDelay(pdMS_TO_TICKS(1000 - t_msec % 1000));
    }

    // from here on we are on top of next second

    tv.tv_sec = time_to_set;
    tv.tv_usec = 0;
    sntp_sync_time(&tv);

    ESP_LOGI(TAG, "[%0.3f] UTC time: %d.000 sec", _seconds(), time_to_set);

    // if we have a precise time timesource, set RTC time and shift RTC_INT
    // pulse to top of second
#ifdef HAS_RTC
    if ((mytimesource == _gps) || (mytimesource == _lora))
      set_rtctime(time_to_set);
#endif

    // if we have a software pps timer, shift it to top of second
    if (ppsIRQ != NULL) {
      timerWrite(ppsIRQ, 0); // reset pps timer
      CLOCKIRQ();            // fire clock pps to advance wall clock by 1 sec
    }

    timeSource = mytimesource; // set global variable

    timesyncer.attach(TIME_SYNC_INTERVAL * 60, setTimeSyncIRQ);
    ESP_LOGD(TAG, "[%0.3f] Timesync finished, time was set | timesource=%d",
             _seconds(), mytimesource);
  } else {
    timesyncer.attach(TIME_SYNC_INTERVAL_RETRY * 60, setTimeSyncIRQ);
    ESP_LOGV(TAG,
             "[%0.3f] Failed to synchronise time from source %c | unix sec "
             "obtained from source: %d | unix sec at program compilation: %d",
             _seconds(), timeSetSymbols[mytimesource], time_to_set,
             compileTime());
  }
}

// helper function to setup a pulse per second for time synchronisation
uint8_t timepulse_init() {

  // set esp-idf API sntp sync mode
  // sntp_init();
  sntp_set_sync_mode(SNTP_SYNC_MODE_IMMED);

// use time pulse from GPS as time base with fixed 1Hz frequency
#ifdef GPS_INT

  // setup external interupt pin for rising edge GPS INT
  pinMode(GPS_INT, INPUT_PULLDOWN);
  // setup external rtc 1Hz clock as pulse per second clock
  ESP_LOGI(TAG, "Timepulse: external (GPS)");
  return 1; // success

// use pulse from on board RTC chip as time base with fixed frequency
#elif defined RTC_INT

  // setup external interupt pin for falling edge RTC INT
  pinMode(RTC_INT, INPUT_PULLUP);

  // setup external rtc 1Hz clock as pulse per second clock
  if (I2C_MUTEX_LOCK()) {
    Rtc.SetSquareWavePinClockFrequency(DS3231SquareWaveClock_1Hz);
    Rtc.SetSquareWavePin(DS3231SquareWavePin_ModeClock);
    I2C_MUTEX_UNLOCK();
    ESP_LOGI(TAG, "Timepulse: external (RTC)");
    return 1; // success
  } else {
    ESP_LOGE(TAG, "RTC initialization error, I2C bus busy");
    return 0; // failure
  }
  return 1; // success

#else
  // use ESP32 hardware timer as time base with adjustable frequency
  ppsIRQ = timerBegin(1, 8000, true);   // set 80 MHz prescaler to 1/10000 sec
  timerAlarmWrite(ppsIRQ, 10000, true); // 1000ms
  ESP_LOGI(TAG, "Timepulse: internal (ESP32 hardware timer)");
  return 1; // success

#endif
} // timepulse_init

void timepulse_start(void) {
#ifdef GPS_INT // start external clock gps pps line
  attachInterrupt(digitalPinToInterrupt(GPS_INT), CLOCKIRQ, RISING);
#elif defined RTC_INT // start external clock rtc
  attachInterrupt(digitalPinToInterrupt(RTC_INT), CLOCKIRQ, FALLING);
#else                 // start internal clock esp32 hardware timer
  timerAttachInterrupt(ppsIRQ, &CLOCKIRQ, true);
  timerAlarmEnable(ppsIRQ);
#endif

  // get time if we don't have one
  if (timeSource != _set)
    setTimeSyncIRQ(); // init systime by RTC or GPS or LORA
  // start cyclic time sync
  timesyncer.attach(TIME_SYNC_INTERVAL * 60, setTimeSyncIRQ);
}

// interrupt service routine triggered by either pps or esp32 hardware timer
void IRAM_ATTR CLOCKIRQ(void) {

  BaseType_t xHigherPriorityTaskWoken = pdFALSE;

// advance wall clock, if we have
#if (defined HAS_IF482 || defined HAS_DCF77)
  xTaskNotifyFromISR(ClockTask, uint32_t(time(NULL)), eSetBits,
                     &xHigherPriorityTaskWoken);
#endif

// flip time pulse ticker, if needed
#ifdef HAS_DISPLAY
#if (defined GPS_INT || defined RTC_INT)
  TimePulseTick = !TimePulseTick; // flip pulse ticker
#endif
#endif

  // yield only if we should
  if (xHigherPriorityTaskWoken)
    portYIELD_FROM_ISR();
}

// helper function to check plausibility of a given epoch time
bool timeIsValid(time_t const t) {
  // is t a time in the past? we use compile time to guess
  // compile time is some local time, but we do not know it's time zone
  // thus, we go 1 full day back to be sure to catch a time in the past
  return (t > (compileTime() - 86400));
}

// helper function to calculate serial transmit time
TickType_t tx_Ticks(uint32_t framesize, unsigned long baud, uint32_t config,
                    int8_t rxPin, int8_t txPins) {

  uint32_t databits = ((config & 0x0c) >> 2) + 5;
  uint32_t stopbits = ((config & 0x20) >> 5) + 1;
  uint32_t txTime = (databits + stopbits + 1) * framesize * 1000.0 / baud;
  // +1 for the startbit

  return round(txTime);
}

void clock_init(void) {

// setup clock output interface
#ifdef HAS_IF482
  IF482.begin(HAS_IF482);
#elif defined HAS_DCF77
  pinMode(HAS_DCF77, OUTPUT);
#endif

  xTaskCreatePinnedToCore(clock_loop,  // task function
                          "clockloop", // name of task
                          3072,        // stack size of task
                          (void *)1,   // task parameter
                          6,           // priority of the task
                          &ClockTask,  // task handle
                          1);          // CPU core

  _ASSERT(ClockTask != NULL); // has clock task started?
} // clock_init

void clock_loop(void *taskparameter) { // ClockTask

  uint64_t ClockPulse = 0;
  uint32_t current_time = 0, previous_time = 0;
  int8_t ClockMinute = -1;
  time_t tt;
  struct tm t = {0};
#ifdef HAS_TWO_LED
  static bool led1_state = false;
#endif

  // output the next second's pulse/telegram after pps arrived
  for (;;) {

    // wait for timepulse and store UTC time
    xTaskNotifyWait(0x00, ULONG_MAX, &current_time, portMAX_DELAY);

    if ((sntp_get_sync_status() == SNTP_SYNC_STATUS_IN_PROGRESS) ||
        !(timeIsValid(current_time)) || (current_time == previous_time))
      continue;

    // set calendar time for next second of clock output
    tt = (time_t)(current_time + 1);
    localtime_r(&tt, &t);
    tt = mktime(&t);

#if defined HAS_IF482

    // wait until moment to fire. Normally we won't get notified during this
    // timespan, except when next pps pulse arrives while waiting, because pps
    // was adjusted by recent time sync, then advance next_time one second
    if (xTaskNotifyWait(0x00, ULONG_MAX, &current_time, txDelay) == pdTRUE) {
      tt = (time_t)(current_time + 1);
      localtime_r(&tt, &t);
      tt = mktime(&t);
    }

    // send IF482 telegram
    IF482.print(IF482_Frame(tt)); // note: telegram is for *next* second

    ESP_LOGD(TAG, "[%0.3f] IF482: %s", _seconds(), IF482_Frame(tt).c_str());

#elif defined HAS_DCF77

    // load new frame if second 59 is reached
    if (t.tm_sec == 0) {
      ClockMinute = t.tm_min;
      t.tm_min++;                  // follow-up minute
      mktime(&t);                  // normalize calendar time
      ClockPulse = DCF77_Frame(t); // generate pulse frame

      /* to do here: leap second handling in second 59 */

      ESP_LOGD(TAG, "[%0.3f] DCF77: new frame for min %d", _seconds(),
               t.tm_min);
    } else {

      // generate impulse
      if (t.tm_min == ClockMinute) { // ensure frame is recent
        DCF77_Pulse(ClockPulse & 1); // output next second
        ClockPulse >>= 1;
      }
    }

#endif

// pps blink on secondary LED if we have one
#ifdef HAS_TWO_LED
    if (led1_state)
      switch_LED1(LED_OFF);
    else
      switch_LED1(LED_ON);
    led1_state = !led1_state;
#endif

    previous_time = current_time;

  } // for
} // clock_loop()

// we use compile date to create a time_t reference "in the past"
time_t compileTime(void) {

  char s_month[5];
  int year;
  struct tm t = {0};
  static const char month_names[] = "JanFebMarAprMayJunJulAugSepOctNovDec";

  // store compile time once it's calculated
  static time_t secs = -1;

  if (secs == -1) {

    // determine date
    sscanf(__DATE__, "%s %d %d", s_month, &t.tm_mday, &year);
    t.tm_mon = (strstr(month_names, s_month) - month_names) / 3;
    t.tm_year = year - 1900;
    // determine time
    sscanf(__TIME__, "%d:%d:%d", &t.tm_hour, &t.tm_min, &t.tm_sec);

    // convert to secs local time
    secs = mktime(&t);
  }

  return secs;
}

static bool IsLeapYear(short year) {
  if (year % 4 != 0)
    return false;
  if (year % 100 != 0)
    return true;
  return (year % 400) == 0;
}

// convert UTC tm time to time_t epoch time
time_t mkgmtime(const struct tm *ptm) {
  const int SecondsPerMinute = 60;
  const int SecondsPerHour = 3600;
  const int SecondsPerDay = 86400;
  const int DaysOfMonth[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  time_t secs = 0;
  // tm_year is years since 1900
  int year = ptm->tm_year + 1900;
  for (int y = 1970; y < year; ++y) {
    secs += (IsLeapYear(y) ? 366 : 365) * SecondsPerDay;
  }
  // tm_mon is month from 0..11
  for (int m = 0; m < ptm->tm_mon; ++m) {
    secs += DaysOfMonth[m] * SecondsPerDay;
    if (m == 1 && IsLeapYear(year))
      secs += SecondsPerDay;
  }
  secs += (ptm->tm_mday - 1) * SecondsPerDay;
  secs += ptm->tm_hour * SecondsPerHour;
  secs += ptm->tm_min * SecondsPerMinute;
  secs += ptm->tm_sec;
  return secs;
}