ESP32-PaxCounter/src/rtctime.cpp

#include "rtctime.h"

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

hw_timer_t *clockCycle = NULL;

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

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

  // setup external interupt for active low RTC INT pin
  pinMode(GPS_INT, INPUT_PULLDOWN);
  // setup external rtc 1Hz clock as pulse per second clock
  ESP_LOGI(TAG, "Time base: 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 for active low RTC INT pin
  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, "Time base: external (RTC)");
    return 1; // success
  } else {
    ESP_LOGE(TAG, "I2c bus busy - RTC initialization error");
    return 0; // failure
  }
  return 1; // success

#else
  // use ESP32 hardware timer as time base with adjustable frequency
  clockCycle = timerBegin(1, 8000, true); // set 80 MHz prescaler to 1/10000 sec
  timerAlarmWrite(clockCycle, 10000, true); // 1000ms
  ESP_LOGI(TAG, "Time base: 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(clockCycle, &CLOCKIRQ, true);
  timerAlarmEnable(clockCycle);
#endif
}

// interrupt service routine triggered by either pps or esp32 hardware timer
void IRAM_ATTR CLOCKIRQ(void) {
  if (ClockTask != NULL)
    xTaskNotifyFromISR(ClockTask, xTaskGetTickCountFromISR(), eSetBits, NULL);
#if defined GPS_INT || defined RTC_INT
  xSemaphoreGiveFromISR(TimePulse, NULL);
  TimePulseTick = !TimePulseTick; // flip ticker
#endif
  portYIELD_FROM_ISR();
}

// helper function to sync systime on start of next second
int sync_SysTime(time_t t) {
  if (sync_TimePulse() && (t)) { // wait for start of next second by timepulse
    setTime(t + 1);
    ESP_LOGD(TAG, "Systime synced on second");
    return 1; // success
  } else
    return 0; // failure
}

int sync_SysTime(uint32_t t) { // t is epoch seconds starting 1.1.1970
  return sync_SysTime(static_cast<time_t>(t));
}

// helper function to sync moment on timepulse
int sync_TimePulse(void) {
  // sync on top of next second by timepulse
  if (xSemaphoreTake(TimePulse, pdMS_TO_TICKS(1100)) == pdTRUE) {
    return 1;
  } // success
  else
    ESP_LOGW(TAG, "Missing timepulse, time not synced");
  return 0; // failure
}

// helper function to fetch current second from most precise time source
time_t best_time(void) {

  time_t t;

#ifdef HAS_GPS // gps is our primary time source if present
  t = get_gpstime();
  if (t) // did we get a valid time?
    return t;
#endif

  /*
  // Reading RTC time from chip take too long on i2c bus, causes jitter
  #ifdef HAS_RTC // rtc is our secondary time source if present
    t = get_rtctime();
    if (t)
      return t;
  #endif
  */

  // else we use systime as fallback source
  return now();
}

#ifdef HAS_RTC // we have hardware RTC

RtcDS3231<TwoWire> Rtc(Wire); // RTC hardware i2c interface

// initialize RTC
int rtc_init(void) {

  // return = 0 -> error / return = 1 -> success

  // block i2c bus access
  if (I2C_MUTEX_LOCK()) {

    Wire.begin(HAS_RTC);
    Rtc.Begin();

    RtcDateTime compiled = RtcDateTime(__DATE__, __TIME__);

    if (!Rtc.IsDateTimeValid()) {
      ESP_LOGW(TAG,
               "RTC has no valid RTC date/time, setting to compilation date");
      Rtc.SetDateTime(compiled);
    }

    if (!Rtc.GetIsRunning()) {
      ESP_LOGI(TAG, "RTC not running, starting now");
      Rtc.SetIsRunning(true);
    }

    RtcDateTime now = Rtc.GetDateTime();

    if (now < compiled) {
      ESP_LOGI(TAG, "RTC date/time is older than compilation date, updating");
      Rtc.SetDateTime(compiled);
    }

    // configure RTC chip
    Rtc.Enable32kHzPin(false);
    Rtc.SetSquareWavePin(DS3231SquareWavePin_ModeNone);

  } else {
    ESP_LOGE(TAG, "I2c bus busy - RTC initialization error");
    goto error;
  }

  I2C_MUTEX_UNLOCK(); // release i2c bus access
  ESP_LOGI(TAG, "RTC initialized");
  return 1;

error:
  I2C_MUTEX_UNLOCK(); // release i2c bus access
  return 0;

} // rtc_init()

int set_rtctime(time_t t) { // t is seconds epoch time starting 1.1.1970
  if (I2C_MUTEX_LOCK()) {
    Rtc.SetDateTime(RtcDateTime(t));
    I2C_MUTEX_UNLOCK(); // release i2c bus access
    ESP_LOGI(TAG, "RTC calibrated");
    return 1; // success
  }
  ESP_LOGE(TAG, "RTC set time failure");
  return 0; // failure
} // set_rtctime()

int set_rtctime(uint32_t t) { // t is epoch seconds starting 1.1.1970
  return set_rtctime(static_cast<time_t>(t));
  // set_rtctime()
}

time_t get_rtctime(void) {
  // !! never call now() or delay in this function, this would break this
  // function to be used as SyncProvider for Time.h
  time_t t = 0; // 0 effects calling SyncProvider() to not set time
  // block i2c bus access
  if (I2C_MUTEX_LOCK()) {
    if (Rtc.IsDateTimeValid()) {
      RtcDateTime tt = Rtc.GetDateTime();
      t = tt.Epoch32Time();
    }
    I2C_MUTEX_UNLOCK(); // release i2c bus access
  }
  return t;
} // get_rtctime()

float get_rtctemp(void) {
  // block i2c bus access
  if (I2C_MUTEX_LOCK()) {
    RtcTemperature temp = Rtc.GetTemperature();
    I2C_MUTEX_UNLOCK(); // release i2c bus access
    return temp.AsFloatDegC();
  } // while
  return 0;
} // get_rtctemp()

#endif // HAS_RTC