GPS handling and timesync code refactored

include/globals.h

@@ -82,8 +82,6 @@ typedef struct {
   uint8_t satellites;
   uint16_t hdop;
   int16_t altitude;
-  uint32_t time_age;
-  tmElements_t timedate;
 } gpsStatus_t;
 
 typedef struct {

include/gpsread.h

@@ -10,18 +10,15 @@
 #endif
 
 #define NMEA_FRAME_SIZE 82 // NEMA has a maxium of 82 bytes per record
-#define NMEA_BUFFERTIME 50 // 50ms safety time regardless
 
 extern TinyGPSPlus gps; // Make TinyGPS++ instance globally availabe
-extern gpsStatus_t
-    gps_status; // Make struct for storing gps data globally available
 extern TaskHandle_t GpsTask;
 
 int gps_init(void);
-void IRAM_ATTR gps_storetime(gpsStatus_t *gps_store);
+int gps_config();
 void gps_storelocation(gpsStatus_t *gps_store);
 void gps_loop(void *pvParameters);
-time_t fetch_gpsTime(gpsStatus_t value, uint16_t *msec);
+time_t fetch_gpsTime(uint16_t *msec);
-int gps_config();
+time_t fetch_gpsTime(void);
 
 #endif

src/gpsread.cpp

@@ -5,7 +5,12 @@
 // Local logging tag
 static const char TAG[] = __FILE__;
 
+// we use NMEA $GPZDA sentence field 1 for time synchronization
+// $GPZDA gives time for preceding pps pulse, but does not has a constant offset
 TinyGPSPlus gps;
+TinyGPSCustom gpstime(gps, "GPZDA", 1); // field 1 = UTC time
+static const String ZDA_Request = "$EIGPQ,ZDA*39\r\n";
+
 gpsStatus_t gps_status = {0};
 TaskHandle_t GpsTask;
 
@@ -27,7 +32,7 @@ int gps_init(void) {
     return 0;
   }
 
-#if defined GPS_SERIAL
+#ifdef GPS_SERIAL
   GPS_Serial.begin(GPS_SERIAL);
   ESP_LOGI(TAG, "Using serial GPS");
 #elif defined GPS_I2C
@@ -55,11 +60,11 @@ int gps_config() {
   int rslt = 1; // success
 #if defined GPS_SERIAL
 
-  /* to come */
+  /* insert user configuration here, if needed */
 
 #elif defined GPS_I2C
 
-  /* to come */
+  /* insert user configuration here, if needed */
 
 #endif
   return rslt;
@@ -68,7 +73,7 @@ int gps_config() {
 // store current GPS location data in struct
 void gps_storelocation(gpsStatus_t *gps_store) {
   if (gps.location.isUpdated() && gps.location.isValid() &&
-      (gps.time.age() < 1500)) {
+      (gps.location.age() < 1500)) {
     gps_store->latitude = (int32_t)(gps.location.lat() * 1e6);
     gps_store->longitude = (int32_t)(gps.location.lng() * 1e6);
     gps_store->satellites = (uint8_t)gps.satellites.value();
@@ -77,34 +82,55 @@ void gps_storelocation(gpsStatus_t *gps_store) {
   }
 }
 
-// store current GPS timedate in struct
+// function to fetch current time from struct; note: this is costly
-void IRAM_ATTR gps_storetime(gpsStatus_t *gps_store) {
+time_t fetch_gpsTime(uint16_t *msec) {
 
-  if (gps.time.isUpdated() && gps.date.isValid() && (gps.time.age() < 1000)) {
+  time_t time_sec = 0;
 
-    gps_store->time_age = gps.time.age() + nmea_txDelay_ms;
+  // poll NMEA $GPZDA sentence
-    gps_store->timedate.Second = gps.time.second();
+#ifdef GPS_SERIAL
-    gps_store->timedate.Minute = gps.time.minute();
+  GPS_Serial.print(ZDA_Request);
-    gps_store->timedate.Hour = gps.time.hour();
+#elif defined GPS_I2C
-    gps_store->timedate.Day = gps.date.day();
+  Wire.print(ZDA_Request);
-    gps_store->timedate.Month = gps.date.month();
+#endif
-    gps_store->timedate.Year =
+
+  // wait for gps NMEA answer
+  vTaskDelay(tx_Ticks(NMEA_FRAME_SIZE, GPS_SERIAL));
+
+  // did we get a current time?
+  if (gpstime.isUpdated() && gpstime.isValid()) {
+
+    tmElements_t tm;
+
+    String rawtime = gpstime.value();
+    uint32_t time_bcd = rawtime.toFloat() * 100;
+    uint32_t delay_ms = gpstime.age() + nmea_txDelay_ms;
+    uint8_t year =
         CalendarYrToTm(gps.date.year()); // year offset from 1970 in microTime.h
 
-  } else
+    ESP_LOGD(TAG, "time [bcd]: %u", time_bcd);
-    gps_store->timedate = {0};
-}
 
-// function to fetch current time from struct; note: this is costly
+    tm.Second = (time_bcd / 100) % 100;   // second
-time_t fetch_gpsTime(gpsStatus_t value, uint16_t *msec) {
+    tm.Minute = (time_bcd / 10000) % 100; // minute
+    tm.Hour = time_bcd / 1000000;         // hour
+    tm.Day = gps.date.day();              // day
+    tm.Month = gps.date.month();          // month
+    tm.Year = year;                       // year
 
-  *msec = 1000 - value.time_age;
+    // add protocol delay to time with millisecond precision
-  time_t t = timeIsValid(makeTime(value.timedate));
+    time_sec = makeTime(tm) + delay_ms / 1000;
-  ESP_LOGD(TAG, "GPS time: %d | time age: %d", t, value.time_age);
+    *msec = (delay_ms % 1000) ? delay_ms % 1000 : 0;
-  return t;
+  }
+
+  return timeIsValid(time_sec);
 
 } // fetch_gpsTime()
 
+time_t fetch_gpsTime(void) {
+  uint16_t msec;
+  return fetch_gpsTime(&msec);
+}
+
 // GPS serial feed FreeRTos Task
 void gps_loop(void *pvParameters) {
 
@@ -113,7 +139,7 @@ void gps_loop(void *pvParameters) {
   while (1) {
 
     if (cfg.payloadmask && GPS_DATA) {
-#if defined GPS_SERIAL
+#ifdef GPS_SERIAL
       // feed GPS decoder with serial NMEA data from GPS device
       while (GPS_Serial.available()) {
         gps.encode(GPS_Serial.read());
@@ -128,7 +154,7 @@ void gps_loop(void *pvParameters) {
     } // if
 
     // show NMEA data in verbose mode, useful for debugging GPS
-    ESP_LOGV(TAG, "GPS NMEA data: passed %d / failed: %d / with fix: %d",
+    ESP_LOGV(TAG, "GPS NMEA data: passed %u / failed: %u / with fix: %u",
              gps.passedChecksum(), gps.failedChecksum(),
              gps.sentencesWithFix());
 

src/main.cpp

@@ -419,9 +419,9 @@ void setup() {
 #warning you did not specify a time source, time will not be synched
 #endif
 
-  // initialize gps time
+// initialize gps time
 #if (HAS_GPS)
-  gps_storetime(&gps_status);
+  fetch_gpsTime();
 #endif
 
 #if (defined HAS_IF482 || defined HAS_DCF77)

src/rcommand.cpp

@@ -253,6 +253,7 @@ void get_status(uint8_t val[]) {
 void get_gps(uint8_t val[]) {
   ESP_LOGI(TAG, "Remote command: get gps status");
 #if (HAS_GPS)
+  gpsStatus_t gps_status;
   gps_storelocation(&gps_status);
   payload.reset();
   payload.addGPS(gps_status);

src/senddata.cpp

@@ -87,6 +87,7 @@ void sendCounter() {
     case GPS_DATA:
       // send GPS position only if we have a fix
       if (gps.location.isValid()) {
+        gpsStatus_t gps_status;
         gps_storelocation(&gps_status);
         payload.reset();
         payload.addGPS(gps_status);

src/timekeeper.cpp

@@ -30,7 +30,7 @@ void calibrateTime(void) {
 
 #if (HAS_GPS)
   // fetch recent time from last NMEA record
-  t = fetch_gpsTime(gps_status, &t_msec);
+  t = fetch_gpsTime(&t_msec);
   if (t) {
     timeSource = _gps;
     goto finish;
@@ -124,11 +124,6 @@ void IRAM_ATTR CLOCKIRQ(void) {
 
   SyncToPPS(); // advance systime, see microTime.h
 
-  // store recent gps time
-#if (HAS_GPS)
-  gps_storetime(&gps_status);
-#endif
-
 // advance wall clock, if we have
 #if (defined HAS_IF482 || defined HAS_DCF77)
   xTaskNotifyFromISR(ClockTask, uint32_t(now()), eSetBits,

src/timesync.cpp

@@ -211,22 +211,22 @@ int recv_timesync_ans(uint8_t seq_no, uint8_t buf[], uint8_t buf_len) {
 void IRAM_ATTR setMyTime(uint32_t t_sec, uint16_t t_msec,
                          timesource_t mytimesource) {
 
-  time_t time_to_set = (time_t)(t_sec);
+  time_t time_to_set = (time_t)(t_sec + t_msec / 1000);
 
   if (timeIsValid(time_to_set)) {
 
-    ESP_LOGD(TAG, "[%0.3f] UTC epoch time: %d.%03d sec", millis() / 1000.0,
-             time_to_set, t_msec);
     // wait until top of second with millisecond precision
-    if (t_msec) {
+    if (t_msec % 1000) {
-      vTaskDelay(pdMS_TO_TICKS(1000 - t_msec));
       time_to_set++;
+      vTaskDelay(pdMS_TO_TICKS(1000 - t_msec % 1000));
     }
 
-// if we got a timesource, set RTC time and calibrate RTC_INT pulse on top of
+    ESP_LOGD(TAG, "[%0.3f] UTC epoch time: %d.%03d sec", millis() / 1000.0,
-// second
+             time_to_set, t_msec % 1000);
+
+// if we got a timesource, set RTC time and RTC_INT pulse on top of second
 #ifdef HAS_RTC
-    if (mytimesource != _rtc)
+    if ((mytimesource == _gps) || (mytimesource == _lora))
       set_rtctime(time_to_set);
 #endif
 
@@ -234,6 +234,7 @@ void IRAM_ATTR setMyTime(uint32_t t_sec, uint16_t t_msec,
 #if (!defined GPS_INT && !defined RTC_INT)
     timerWrite(ppsIRQ, 0); // reset pps timer
     CLOCKIRQ();            // fire clock pps, this advances time 1 sec
+    time_to_set--;
 #endif
 
     setTime(time_to_set); // set the time on top of second
@@ -249,8 +250,8 @@ void IRAM_ATTR setMyTime(uint32_t t_sec, uint16_t t_msec,
   }
 }
 
+// create task for timeserver handshake processing, called from main.cpp
 void timesync_init() {
-  // create task for timeserver handshake processing, called from main.cpp
   xTaskCreatePinnedToCore(process_timesync_req, // task function
                           "timesync_req",       // name of task
                           2048,                 // stack size of task