Feature RTC support added (experimental)

include/cyclic.h

@@ -11,6 +11,11 @@
 #include "bme680mems.h"
 #endif
 
+// Needed for RTC time sync if RTC present on board
+#ifdef HAS_RTC
+#include "rtc.h"
+#endif
+
 void doHousekeeping(void);
 void do_timesync(void);
 uint64_t uptime(void);

include/lorawan.h

@@ -17,6 +17,11 @@
 #include <Wire.h>
 #endif
 
+// Needed for RTC time sync if RTC present on board
+#ifdef HAS_RTC
+#include "rtc.h"
+#endif
+
 extern QueueHandle_t LoraSendQueue;
 
 void onEvent(ev_t ev);

include/rtc.h

@@ -0,0 +1,16 @@
+#ifndef _RTC_H
+#define _RTC_H
+
+#include "globals.h"
+#include <Wire.h> // must be included here so that Arduino library object file references work
+#include <RtcDS3231.h>
+
+extern RtcDS3231<TwoWire> Rtc; // Make RTCDS3231 instance globally availabe
+
+int rtc_init(void);
+int set_rtc(uint32_t UTCTime);
+int set_rtc(RtcDateTime now);
+uint32_t get_rtc();
+float get_rtc_temp();
+
+#endif

src/cyclic.cpp

@@ -128,6 +128,16 @@ void do_timesync() {
   if (gps.time.isValid()) {
     setTime(gps.time.hour(), gps.time.minute(), gps.time.second(),
             gps.date.day(), gps.date.month(), gps.date.year());
+#ifdef HAS_RTC
+    RtcDateTime now;
+    now.year = gps.time.year();
+    now.month = gps.date.month();
+    now.dayOfMonth = gps.date.day();
+    now.hour = gps.time.hour();
+    now.minute = gps.time.minute();
+    now.second = gps.time.second();
+    set_rtc(now);
+#endif
     ESP_LOGI(TAG, "Time synced by GPS to %02d:%02d:%02d", hour(), minute(),
              second());
     return;

src/lorawan.cpp

@@ -455,6 +455,9 @@ void user_request_network_time_callback(void *pVoidUserUTCTime,
 
   // Update system time with  time read from the network
   setTime(*pUserUTCTime);
-  ESP_LOGI(TAG, "Time synced by LoRa network to %02d:%02d:%02d", hour(),
-           minute(), second());
+#ifdef HAS_RTC
+  set_rtc(*pUserUTCTime);
+#endif
+      ESP_LOGI(TAG, "Time synced by LoRa network to %02d:%02d:%02d", hour(),
+               minute(), second());
 }

src/main.cpp

@@ -171,6 +171,12 @@ void setup() {
                           0);           // CPU core
 #endif
 
+// initialize RTC
+#ifdef HAS_RTC
+  strcat_P(features, " RTC");
+  assert(rtc_init());
+#endif
+
   // initialize wifi antenna
 #ifdef HAS_ANTENNA_SWITCH
   strcat_P(features, " ANT");

src/rtc.cpp

@@ -0,0 +1,112 @@
+#ifdef HAS_RTC
+
+#include "rtc.h"
+
+// Local logging tag
+static const char TAG[] = "main";
+
+RtcDS3231<TwoWire> Rtc(Wire);
+
+// initialize RTC
+int rtc_init() {
+
+  // return = 0 -> error / return = 1 -> success
+
+  // block i2c bus access
+  if (xSemaphoreTake(I2Caccess, (2 * DISPLAYREFRESH_MS / portTICK_PERIOD_MS)) ==
+      pdTRUE) {
+
+    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;
+  }
+
+  xSemaphoreGive(I2Caccess); // release i2c bus access
+  ESP_LOGI(TAG, "RTC initialized");
+  return 1;
+
+error:
+  xSemaphoreGive(I2Caccess); // release i2c bus access
+  return 0;
+
+} // rtc_init()
+
+int set_rtc(uint32_t UTCTime) {
+  // return = 0 -> error / return = 1 -> success
+#ifdef HAS_RTC
+  // block i2c bus access
+  while (xSemaphoreTake(I2Caccess, 2 * DISPLAYREFRESH_MS) == pdTRUE) {
+    Rtc.SetDateTime(RtcDateTime(UTCTime));
+    xSemaphoreGive(I2Caccess); // release i2c bus access
+    return 1;
+  } // while
+  return 0;
+#endif
+} // set_rtc()
+
+int set_rtc(RtcDateTime now) {
+  // return = 0 -> error / return = 1 -> success
+#ifdef HAS_RTC
+  // block i2c bus access
+  while (xSemaphoreTake(I2Caccess, 2 * DISPLAYREFRESH_MS) == pdTRUE) {
+    Rtc.SetDateTime(now);
+    xSemaphoreGive(I2Caccess); // release i2c bus access
+    return 1;
+  } // while
+  return 0;
+#endif
+} // set_rtc()
+
+uint32_t get_rtc() {
+#ifdef HAS_RTC
+  // block i2c bus access
+  while (xSemaphoreTake(I2Caccess, 2 * DISPLAYREFRESH_MS) == pdTRUE) {
+    if (!Rtc.IsDateTimeValid()) {
+      ESP_LOGW(TAG, "RTC lost confidence in the DateTime");
+      return 0;
+    }
+    xSemaphoreGive(I2Caccess); // release i2c bus access
+    return Rtc.GetDateTime();
+  } // while
+  return 0;
+#endif
+} // get_rtc()
+
+float get_rtc_temp() {
+#ifdef HAS_RTC
+  // block i2c bus access
+  while (xSemaphoreTake(I2Caccess, 2 * DISPLAYREFRESH_MS) == pdTRUE) {
+    RtcTemperature temp = Rtc.GetTemperature();
+    xSemaphoreGive(I2Caccess); // release i2c bus access
+    return temp.AsFloatDegC();
+  } // while
+  return 0;
+#endif
+} // get_rtc()
+
+#endif // HAS_RTC