added keep alive function

README.md

@@ -8,8 +8,9 @@ It is developed for Arduino Uno with Dragino Lora/GPS Shield and for ESP32 TTGO
   - the software supports confirmed uplink and the Arduino will beep
   - You can read the GPS over Hardware Serial or Software Serial, so it's easier for development if you see what is going on during real operation
   - In case of Hardware Serial usage you can enable a Software Serial for debugging
+  - Adding keep alive timer option
  ## To Do
-  - Timed transmission, which also executes when the tracker is not moving. For example every hour, to see if the tracker is still alive.
+  - ~~Timed transmission, which also executes when the tracker is not moving. For example every hour, to see if the tracker is still alive.~~
   - low power option
   - ~~ESP32 support [State: in work, see branch develop. The SPI Config produces backtraces] Hardware: ESP32 Uno, branded as Wemos~~ ESP32 already implemented fot TTGO T-Beam
   - Alternative WiFi Position for ESP32

spgpstrack.ino

@@ -9,6 +9,7 @@
  *      TXspeedLOW - Maximum speed for low speed mode
  *      TXdistHIGH - Transmit Interval distance in high speed mode
  *      TXspeedLOW - Minimum speed for high speed mode
+ *      keepAlive - number of seconds for keep alive sending, even if tracker does not move
  *      SF - Define The LoRaWAN Spreading Factor (DR_SF7 - DR_SF12) 7 and 8 recommended for Mapping
  *      CONFIRMED - enables Confirmed uplinks, ONLY Enable, if you conncect a Buzzer to Pin D5! Otherwise this Feature is useless
  *      SOFT_SERIAL - Uncomment to use Hardware Serial, Otherwise Software Serial is used. In that case connect the GPS Module to RXpin and TXpin
@@ -55,6 +56,10 @@
 // min speed for high speed mode; in km/h
 #define TXspeedHIGH 80
 
+/* keep alive timer in seconds */
+#define keepAlive // comment out if not wanted
+#define keepAliveIntervall 60
+
 /* Define Region */
 #define CFG_eu868
 /* Define Data Rate aka Sporeading Factor */
@@ -108,6 +113,7 @@ static const int RXPin = 4, TXPin = 3;
 #ifdef ESP32
   #include <Ticker.h>
   Ticker tickerSampleGPS;
+  Ticker tickerKeepAlive;
   #include <WiFi.h>
 #endif
 
@@ -145,7 +151,6 @@ CayenneLPP lpp(20);
 uint8_t txBuffer[9];
 #endif
 
-
 // ABP:
 
 // LoRaWAN end-device address (DevAddr, MSB)
@@ -210,6 +215,9 @@ const lmic_pinmap lmic_pins = {
 
 #endif
 
+#ifdef keepAlive
+     unsigned long keepAliveTimer = millis() + keepAliveInervall * 1000;
+#endif
 
 void onEvent (ev_t ev) {
     print(String(os_getTime()));
@@ -350,6 +358,7 @@ void setup() {
       ESP_Serial.begin(GPSBaud, SERIAL_8N1, RXPin, TXPin);
       ESP_Serial.setTimeout(2);  
       tickerSampleGPS.attach_ms(500, sampleGPS);
+      //ticker keepAlive ToDo
     #else
       #ifdef SOFT_SERIAL
       // Setup for Software Serial Option
@@ -430,6 +439,9 @@ void setup() {
 
     // Set data rate and transmit power for uplink (note: txpow seems to be ignored by the library)
     LMIC_setDrTxpow(SF,14);
+
+    // set timer to actual millis + keepAlive value if activate
+
     println("Setup OK");
 }
 
@@ -470,6 +482,7 @@ void loop() {
         //println( "Course: " + String(lastTxCourse));
 
         // If Distance to last TX Point is bigger than the TXdistance Prepare and Trigger Data Transmission
+        // or if the keepAlive timer is reached
         bool transmit = false;
         #ifndef TXspeedModes
           transmit = lastTxDist > TXdist; // No speed modes, Default TX distance
@@ -479,6 +492,13 @@ void loop() {
          ( (gps.speed.kmph() >= TXspeedHIGH ) && (lastTxDist > TXdistHIGH) ) || //High speed mode chek
         (lastTxDist > TXdist); // Default TX distance
         #endif 
+        // check keepAlive timer
+        #ifdef keepAlive  
+          if (keepAliveTimer < millis()){
+            keepAliveTimer = millis() + keepAliveIntervall * 1000; // set new timer value
+            transmit = true;
+          }
+        #endif
         if( transmit ){
          #ifdef DOUBLE_SEND
           doDouble!=doDouble;