LoRa gw to LoRa gw time transfer, time master tracking

src/fdrs_gateway.h

@@ -222,6 +222,10 @@ void loopFDRS()
   handleSerial();
 #ifdef USE_LORA
   handleLoRa();
+  // Ping LoRa time master to estimate time delay in radio link
+  if(timeMasterLoRa != 0x0000 && netTimeOffset == UINT32_MAX) {
+    pingLoRaTimeMaster();
+  }
 #endif
 #ifdef USE_WIFI
   handleMQTT();

src/fdrs_gateway_espnow.h

@@ -20,10 +20,12 @@ const uint8_t broadcast_mac[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
 const uint8_t mac_prefix[] = {MAC_PREFIX};
 uint8_t selfAddress[] = {MAC_PREFIX, UNIT_MAC};
 uint8_t incMAC[6];
+uint8_t timeMasterEspNow[6];
 
 uint8_t ESPNOW1[] = {MAC_PREFIX, ESPNOW_NEIGHBOR_1};
 uint8_t ESPNOW2[] = {MAC_PREFIX, ESPNOW_NEIGHBOR_2};
 extern time_t now;
+bool pingFlag = false;
 
 
 // Set ESP-NOW send and receive callbacks for either ESP8266 or ESP32
@@ -46,6 +48,15 @@ void OnDataRecv(const uint8_t *mac, const uint8_t *incomingData, int len)
     DBG("Incoming ESP-NOW System Packet from 0x" + String(incMAC[5], HEX));
     memcpy(&theCmd, incomingData, sizeof(theCmd));
     memcpy(&incMAC, mac, sizeof(incMAC));
+    switch (theCmd.cmd)
+        {
+        case cmd_ping:
+            pingFlag = true;
+            break;
+        case cmd_time:
+            setTime(theCmd.param);    
+            break;
+        }
     return;
   }
   memcpy(&theData, incomingData, sizeof(theData));
@@ -247,12 +258,16 @@ esp_err_t pingback_espnow()
 // Sends time to both neighbors and all peers
 esp_err_t sendTimeESPNow() {
   
-  esp_err_t result1, result2, result3;
+  esp_err_t result1 = ESP_OK, result2 = ESP_OK, result3 = ESP_OK;
   DBG("Sending time via ESP-NOW");
   SystemPacket sys_packet = { .cmd = cmd_time, .param = now };
 
-  result1 = sendESPNow(ESPNOW1, &sys_packet);
-  result2 = sendESPNow(ESPNOW2, &sys_packet);
+  if(ESPNOW1 != timeMasterEspNow) {
+    result1 = sendESPNow(ESPNOW1, &sys_packet);
+  }
+  if(ESPNOW2 != timeMasterEspNow) {
+    result2 = sendESPNow(ESPNOW2, &sys_packet);
+  }
   result3 = sendESPNow(nullptr, &sys_packet);
 
   if(result1 != ESP_OK || result2 != ESP_OK || result3 != ESP_OK){
@@ -379,6 +394,30 @@ esp_err_t sendESPNow(uint8_t address) {
 
 
 void recvTimeEspNow() {
+  memcpy(timeMasterEspNow, incMAC, sizeof(timeMasterEspNow));
   setTime(theCmd.param); 
   DBG("Received time via ESP-NOW from 0x" + String(incMAC[5], HEX));
+}
+
+// FDRS node pings gateway and listens for a defined amount of time for a reply
+// Blocking function for timeout amount of time (up to timeout time waiting for reply)(IE no callback)
+// Returns the amount of time in ms that the ping takes or predefined value if ping fails within timeout
+uint32_t pingFDRSEspNow(uint8_t *address, uint32_t timeout) {
+    SystemPacket sys_packet = {.cmd = cmd_ping, .param = 0};
+    
+    esp_now_send(address, (uint8_t *)&sys_packet, sizeof(SystemPacket));
+    DBG(" ESP-NOW ping sent.");
+    uint32_t ping_start = millis();
+    pingFlag = false;
+    while ((millis() - ping_start) <= timeout)
+    {
+        yield(); // do I need to yield or does it automatically?
+        if (pingFlag)
+        {
+            DBG("ESP-NOW Ping Reply in " + String(millis() - ping_start) + "ms from 0x" + String(address[5], HEX));
+            return (millis() - ping_start);
+        }
+    }
+    DBG("No ESP-NOW ping returned within " + String(timeout) + "ms.");
+    return UINT32_MAX;
 }

src/fdrs_gateway_lora.h

@@ -100,11 +100,14 @@ volatile bool operationDone = false;  // flag to indicate that a packet was sent
 
 uint16_t LoRa1 = ((mac_prefix[4] << 8) | LORA_NEIGHBOR_1); // Use 2 bytes for LoRa addressing instead of previous 3 bytes
 uint16_t LoRa2 = ((mac_prefix[4] << 8) | LORA_NEIGHBOR_2);
+uint16_t timeMasterLoRa = 0x0000;
 uint16_t loraGwAddress = ((selfAddress[4] << 8) | selfAddress[5]); // last 2 bytes of gateway address
 uint16_t loraBroadcast = 0xFFFF;
 unsigned long receivedLoRaMsg = 0; // Number of total LoRa packets destined for us and of valid size
 unsigned long ackOkLoRaMsg = 0;    // Number of total LoRa packets with valid CRC
 extern time_t now;
+time_t lastTimeMasterPing = 0;
+time_t netTimeOffset = UINT32_MAX;  // One direction of LoRa Ping time in units of seconds (1/2 full ping time)
 
 typedef struct DataBuffer
 {
@@ -432,6 +435,12 @@ crcResult getLoRa()
               transmitLoRa(&sourceMAC, &pingReply, 1);
             }
           }
+          else if (ln == 1 && receiveData[0].cmd == cmd_time) {
+            timeMasterLoRa = sourceMAC;
+            setTime(receiveData[0].param);
+            DBG("Time rcv from LoRa 0x" + String(sourceMAC, HEX));
+            adjTimeforNetDelay(netTimeOffset);
+          }
           else
           { // data we have received is not yet programmed.  How we handle is future enhancement.
             DBG("Received some LoRa SystemPacket data that is not yet handled.  To be handled in future enhancement.");
@@ -461,6 +470,12 @@ crcResult getLoRa()
               transmitLoRa(&sourceMAC, &pingReply, 1);
             }
           }
+          else if (ln == 1 && receiveData[0].cmd == cmd_time) {
+            timeMasterLoRa = sourceMAC;
+            setTime(receiveData[0].param);
+            DBG("Time rcv from LoRa 0x" + String(sourceMAC, HEX));
+            adjTimeforNetDelay(netTimeOffset);
+          }
           else
           { // data we have received is not yet programmed.  How we handle is future enhancement.
             DBG("Received some LoRa SystemPacket data that is not yet handled.  To be handled in future enhancement.");
@@ -656,14 +671,59 @@ void sendTimeLoRa() {
   SystemPacket spTimeLoRa = {.cmd = cmd_time, .param = now};
   transmitLoRa(&loraBroadcast, &spTimeLoRa, 1);
   // Do not send to LoRa peers if their address is 0x..00
-  if((LoRa1 & 0x00FF) != 0x0000) {
+  if(((LoRa1 & 0x00FF) != 0x0000) && (LoRa1 != timeMasterLoRa)) {
   spTimeLoRa.param = now;
   // add LoRa neighbor 1
   transmitLoRa(&LoRa1, &spTimeLoRa, 1);
   }
-  if((LoRa2 & 0x00FF) != 0x0000) {
+  if(((LoRa2 & 0x00FF) != 0x0000) && (LoRa2 != timeMasterLoRa)) {
   spTimeLoRa.param = now;
   // add LoRa neighbor 2
   transmitLoRa(&LoRa2, &spTimeLoRa, 1);
   }
+}
+
+// FDRS Sensor pings gateway and listens for a defined amount of time for a reply
+// Blocking function for timeout amount of time (up to timeout time waiting for reply)(IE no callback)
+// Returns the amount of time in ms that the ping takes or predefined value if ping fails within timeout
+uint32_t pingFDRSLoRa(uint16_t *address, uint32_t timeout)
+{
+    SystemPacket sys_packet = {.cmd = cmd_ping, .param = 0};
+
+    transmitLoRa(address, &sys_packet, 1);
+    DBG("LoRa ping sent to address: 0x" + String(*address, HEX));
+    uint32_t ping_start = millis();
+    pingFlag = false;
+    while ((millis() - ping_start) <= timeout)
+    {
+        handleLoRa();
+        #ifdef ESP8266
+            yield();
+        #endif
+        if (pingFlag)
+        {   
+            DBG("LoRa Ping Returned: " + String(millis() - ping_start) + "ms.");
+            pingFlag = false;
+            return (millis() - ping_start);
+        }
+    }
+    DBG("No LoRa ping returned within " + String(timeout) + "ms.");
+    return UINT32_MAX;
+}
+
+// Pings the LoRa time master periodically to calculate the time delay in the LoRa radio link
+// Returns success or failure of the ping result
+bool pingLoRaTimeMaster() {
+  if(millis() - lastTimeMasterPing > (60000 + random(0,2000))) {
+    time_t pingTimeMs;
+    pingTimeMs = pingFDRSLoRa(&timeMasterLoRa,4000);
+    if(pingTimeMs != UINT32_MAX) {
+      netTimeOffset = pingTimeMs/2/1000;
+      adjTimeforNetDelay(netTimeOffset);
+      lastTimeMasterPing = millis();
+      return true;  
+    }
+    lastTimeMasterPing = millis();
+  }
+  return false;
 }

src/fdrs_gateway_time.h

@@ -251,6 +251,19 @@ void checkDST() {
   return;
 }
 
+// Periodically send time to ESP-NOW or LoRa nodes associated with this gateway/controller
+void sendTime() {
+  if(validTime()) { // Only send time if it is valid
+  DBG("Sending out time");
+  // Only send via Serial interface if WiFi is enabled to prevent loops
+#ifdef USE_WIFI // do not remove this line
+    sendTimeSerial();
+#endif          // do not remove this line
+    sendTimeLoRa();
+    sendTimeESPNow();
+  }
+}
+
 bool setTime(time_t currentTime) {
   slewSecs = 0;
   time_t previousTime = now;
@@ -291,18 +304,6 @@ bool setTime(time_t currentTime) {
   }
 }
 
-// Periodically send time to ESP-NOW or LoRa nodes associated with this gateway/controller
-void sendTime() {
-  if(validTime()) { // Only send time if it is valid
-  DBG("Sending out time");
-  // Only send via Serial interface if WiFi is enabled to prevent loops
-#ifdef USE_WIFI // do not remove this line
-    sendTimeSerial();
-#endif          // do not remove this line
-    sendTimeLoRa();
-    sendTimeESPNow();
-  }
-}
 
 void updateTime() {
 
@@ -319,4 +320,15 @@ void updateTime() {
     sendTime();
     lastTimeSend = millis();
   }
+}
+
+void adjTimeforNetDelay(time_t newOffset) {
+  static time_t previousOffset = 0;
+  updateTime();
+  // check to see if offset and current time are valid
+  if(newOffset < UINT32_MAX && validTimeFlag) {
+    now = now + newOffset - previousOffset;
+    previousOffset = newOffset;
+    DBG("Time adj by " + String(newOffset) + " secs");
+  }
 }

src/fdrs_gateway_wifi.h

@@ -153,7 +153,11 @@ void sendNTPpacket(const char * address) {
 
 void fetchNtpTime() {
   //DBG("GetTime Function");
-  if(WiFi.status() == WL_CONNECTED || eth_connected ) {
+#ifdef USE_ETHERNET
+  if(eth_connected) {
+#else
+  if(WiFi.status() == WL_CONNECTED) {
+#endif
     //DBG("Calling .begin function");
     FDRSNtp.begin(localPort);