add air530 gps sleep support

src/gps/NMEAGPS.cpp

@@ -1,50 +1,6 @@
 #include "NMEAGPS.h"
 #include "configuration.h"
 
-/*
-Helpful translations from the Air530 GPS datasheet
-
-Sat acquision mode
-捕获电流值@3.3v 42.6 mA
-
-sat tracking mode
-跟踪电流值@3.3v 36.7 mA
-
-Low power mode
-低功耗模式@3.3V 0.85 mA
-(发送指令:$PGKC051,0)
-
-Super low power mode
-超低功耗模式@3.3V 31 uA
-(发送指令:$PGKC105,4)
-
-To exit sleep use WAKE pin
-
-Commands to enter sleep
-6、Command: 105
-进入周期性低功耗模式
-Arguments:
-
-Arg1: “0”,正常运行模式 (normal mode)
-“1”,周期超低功耗跟踪模式,需要拉高 WAKE 来唤醒 (periodic low power tracking mode - keeps sat positions, use wake to wake up)
-“2”,周期低功耗模式 (periodic low power mode)
-“4”,直接进入超低功耗跟踪模式,需要拉高 WAKE 来唤醒 (super low power consumption mode immediately, need WAKE to resume)
-“8”,自动低功耗模式,可以通过串口唤醒 (automatic low power mode, wake by sending characters to serial port)
-“9”, 自动超低功耗跟踪模式,需要拉高 WAKE 来唤醒 (automatic low power tracking when possible, need wake pin to resume)
-
-(Arg 2 & 3 only valid if Arg1 is "1" or "2")
-Arg2:运行时间(毫秒),在 Arg1 为 1、2 的周期模式下,此参数起作用
-ON time in msecs
-
-Arg3:睡眠时间(毫秒),在 Arg1 为 1、2 的周期模式下,此参数起作用
-Sleep time in msecs
-
-Example:
-$PGKC105,8*3F<CR><LF>
-This will set automatic low power mode with waking when we send chars to the serial port.  Possibly do this as soon as we get a new 
-location.  When we wake again in a minute we send a character to wake up.
-
-*/
 
 static int32_t toDegInt(RawDegrees d)
 {
@@ -68,6 +24,7 @@ bool NMEAGPS::setup()
 
 void NMEAGPS::loop()
 {
+    // First consume any chars that have piled up at the receiver
     while (_serial_gps->available() > 0) {
         int c = _serial_gps->read();
         // DEBUG_MSG("%c", c);
@@ -78,11 +35,18 @@ void NMEAGPS::loop()
             isConnected = true;
     }
 
+    // If we are overdue for an update, turn on the GPS and at least publish the current status
     uint32_t now = millis();
-    if ((now - lastUpdateMsec) > 20 * 1000) { // Ugly hack for now - limit update checks to once every 20 secs (but still consume
-                                              // serial chars at whatever rate)
-        lastUpdateMsec = now;
+    bool mustPublishUpdate = false;
+    if ((now - lastUpdateMsec) > 30 * 1000 && !wantNewLocation) {
+        // Ugly hack for now - limit update checks to once every 30 secs
+        setWantLocation(true);
+        mustPublishUpdate =
+            true; // Even if we don't have an update this time, we at least want to occasionally publish the current state
+    }
 
+    // Only bother looking at GPS state if we are interested in what it has to say
+    if (wantNewLocation) {
         auto ti = reader.time;
         auto d = reader.date;
         if (ti.isUpdated() && ti.isValid() && d.isValid()) {
@@ -105,6 +69,8 @@ void NMEAGPS::loop()
         hasValidLocation = ((fixtype >= 1) && (fixtype <= 5));
 
         if (reader.location.isUpdated()) {
+            lastUpdateMsec = now;
+
             if (reader.altitude.isValid())
                 altitude = reader.altitude.meters();
 
@@ -112,6 +78,9 @@ void NMEAGPS::loop()
                 auto loc = reader.location.value();
                 latitude = toDegInt(loc.lat);
                 longitude = toDegInt(loc.lng);
+
+                // Once we get a location we no longer desperately want an update
+                setWantLocation(false);
             }
             // Diminution of precision (an accuracy metric) is reported in 10^2 units, so we need to scale down when we use it
             if (reader.hdop.isValid()) {
@@ -128,11 +97,14 @@ void NMEAGPS::loop()
             // expect gps pos lat=37.520825, lon=-122.309162, alt=158
             DEBUG_MSG("new NMEA GPS pos lat=%f, lon=%f, alt=%d, hdop=%g, heading=%f\n", latitude * 1e-7, longitude * 1e-7,
                       altitude, dop * 1e-2, heading * 1e-5);
+            mustPublishUpdate = true;
         }
 
-        // Notify any status instances that are observing us
-        const meshtastic::GPSStatus status =
-            meshtastic::GPSStatus(hasLock(), isConnected, latitude, longitude, altitude, dop, heading, numSatellites);
-        newStatus.notifyObservers(&status);
+        if (mustPublishUpdate) {
+            // Notify any status instances that are observing us
+            const meshtastic::GPSStatus status =
+                meshtastic::GPSStatus(hasLock(), isConnected, latitude, longitude, altitude, dop, heading, numSatellites);
+            newStatus.notifyObservers(&status);
+        }
     }
 }