Use Airoha AG3335 backup mode sleep for faster GPS fix time

src/helpers/sensors/AirohaSleep.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <helpers/sensors/LocationProvider.h>
+
+// Board must keep the GPS RTC backup pin powered and can cut GPS power once we return.
+// Returns true if the command was acked within 3 attempts, otherwise returns false.
+static inline bool airohaEnterSleep(LocationProvider* nmea) {
+  for (uint8_t attempt = 0; attempt < 3; attempt++) {
+    nmea->drain();
+    nmea->sendSentence("$PAIR650,0");
+    if (nmea->waitFor("$PAIR001,650,0", 50)) {  // wait for the command received signal
+      #ifdef GPS_NMEA_DEBUG
+      Serial.printf("Airoha RTC Backup sleep command accepted by GPS after %u attempts\r\n", attempt + 1);
+      #endif
+      nmea->waitFor("$PAIR650,0", 50); // give the GPS 50ms grace to signal it is ready for sleep
+      return true;
+    }
+  }
+  return false;
+}

src/helpers/sensors/LocationProvider.h

@@ -17,6 +17,8 @@ class LocationProvider {
     virtual bool isValid() = 0;
     virtual long getTimestamp() = 0;
     virtual void sendSentence(const char * sentence);
+    virtual bool waitFor(const char* prefix, uint32_t timeout_ms) { return false; }
+    virtual void drain() { }
     virtual void reset() = 0;
     virtual void begin() = 0;
     virtual void stop() = 0;

src/helpers/sensors/MicroNMEALocationProvider.h

@@ -129,10 +129,31 @@ public :
         return dt.unixtime();
     } 
 
+    void drain() { while (_gps_serial->available()) _gps_serial->read(); }
+
+    const char* getSentence() const { return nmea.getSentence(); }
+
     void sendSentence(const char *sentence) override {
         nmea.sendSentence(*_gps_serial, sentence);
     }
 
+    bool waitFor(const char* prefix, uint32_t timeout_ms) {
+        size_t plen = strlen(prefix);
+        uint32_t timeout = millis() + timeout_ms;
+        while ((int32_t)(millis() - timeout) < 0) {
+            if (_gps_serial->available()) {
+                char c = _gps_serial->read();
+                #ifdef GPS_NMEA_DEBUG
+                Serial.print(c);
+                #endif
+                if (nmea.process(c) && strncmp(nmea.getSentence(), prefix, plen) == 0) return true;
+            } else {
+                yield();
+            }
+        }
+        return false;
+    }
+
     void loop() override {
 
         while (_gps_serial->available()) {

variants/meshtracker_x1/target.cpp

@@ -1,6 +1,7 @@
 #include <Arduino.h>
 #include "target.h"
 #include <helpers/sensors/MicroNMEALocationProvider.h>
+#include <helpers/sensors/AirohaSleep.h>
 
 MeshTrackerX1Board board;
 
@@ -27,46 +28,27 @@ mesh::LocalIdentity radio_new_identity() {
 
 void MeshTrackerX1SensorManager::start_gps() {
   gps_active = true;
-  // this init sequence comes from seeed examples and deals with all gps pins
-  pinMode(GPS_EN, OUTPUT);
   digitalWrite(GPS_EN, HIGH);
   delay(10);
-  pinMode(GPS_VRTC_EN, OUTPUT);
-  digitalWrite(GPS_VRTC_EN, HIGH);
-  delay(10);
-
-  pinMode(GPS_RESET, OUTPUT);
-  digitalWrite(GPS_RESET, HIGH);
-  delay(10);
-  digitalWrite(GPS_RESET, LOW);
-
-  pinMode(GPS_SLEEP_INT, OUTPUT);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
-  pinMode(GPS_RTC_INT, OUTPUT);
-  digitalWrite(GPS_RTC_INT, LOW);
-}
-
-void MeshTrackerX1SensorManager::sleep_gps() {
-  gps_active = false;
-  digitalWrite(GPS_VRTC_EN, HIGH);   // keep RTC alive for faster fix on wake
-  digitalWrite(GPS_EN, LOW);
-  digitalWrite(GPS_RESET, LOW);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
+  digitalWrite(GPS_RTC_INT, HIGH);
+  delay(5);
   digitalWrite(GPS_RTC_INT, LOW);
 }
 
 void MeshTrackerX1SensorManager::stop_gps() {
   gps_active = false;
-  digitalWrite(GPS_VRTC_EN, LOW);
+  digitalWrite(GPS_VRTC_EN, HIGH);   // keep GPS RTC alive for faster fix on wake
+  digitalWrite(GPS_RTC_INT, LOW);    // make sure this is LOW so we can pulse it to wake
+  airohaEnterSleep(_nmea);
   digitalWrite(GPS_EN, LOW);
-  digitalWrite(GPS_RESET, LOW);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
-  digitalWrite(GPS_RTC_INT, LOW);
 }
 
 bool MeshTrackerX1SensorManager::begin() {
   // init GPS
   Serial1.begin(GPS_BAUD_RATE);
+  digitalWrite(GPS_RESET, HIGH);
+  delay(10);
+  digitalWrite(GPS_RESET, LOW);
 
   // init SPA06-003 barometer
   baro_ok = spa06.begin(SPA06_003_DEFAULT_ADDR, &Wire) || spa06.begin(0x76, &Wire);
@@ -122,7 +104,7 @@ const char* MeshTrackerX1SensorManager::getSettingValue(int i) const {
 bool MeshTrackerX1SensorManager::setSettingValue(const char* name, const char* value) {
   if (strcmp(name, "gps") == 0) {
     if (strcmp(value, "0") == 0) {
-      sleep_gps(); // sleep for faster fix !
+      stop_gps();
     } else {
       start_gps();
     }

variants/t1000-e/target.cpp

@@ -2,6 +2,7 @@
 #include "t1000e_sensors.h"
 #include "target.h"
 #include <helpers/sensors/MicroNMEALocationProvider.h>
+#include <helpers/sensors/AirohaSleep.h>
 
 T1000eBoard board;
 
@@ -81,56 +82,28 @@ mesh::LocalIdentity radio_new_identity() {
 
 void T1000SensorManager::start_gps() {
   gps_active = true;
-  //_nmea->begin();
-  // this init sequence should be better 
-  // comes from seeed examples and deals with all gps pins
-  pinMode(GPS_EN, OUTPUT);
   digitalWrite(GPS_EN, HIGH);
   delay(10);
-  pinMode(GPS_VRTC_EN, OUTPUT);
-  digitalWrite(GPS_VRTC_EN, HIGH);
-  delay(10);
-
-  pinMode(GPS_RESET, OUTPUT);
-  digitalWrite(GPS_RESET, HIGH);
-  delay(10);
-  digitalWrite(GPS_RESET, LOW);
-
-  pinMode(GPS_SLEEP_INT, OUTPUT);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
-  pinMode(GPS_RTC_INT, OUTPUT);
+  digitalWrite(GPS_RTC_INT, HIGH);
+  delay(5);
   digitalWrite(GPS_RTC_INT, LOW);
-  pinMode(GPS_RESETB, INPUT_PULLUP);
-}
-
-void T1000SensorManager::sleep_gps() {
-  gps_active = false;
-  digitalWrite(GPS_VRTC_EN, HIGH);
-  digitalWrite(GPS_EN, LOW);
-  digitalWrite(GPS_RESET, HIGH);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
-  digitalWrite(GPS_RTC_INT, LOW);
-  pinMode(GPS_RESETB, OUTPUT);
-  digitalWrite(GPS_RESETB, LOW);
-  //_nmea->stop();
 }
 
 void T1000SensorManager::stop_gps() {
   gps_active = false;
-  digitalWrite(GPS_VRTC_EN, LOW);
+  digitalWrite(GPS_VRTC_EN, HIGH);   // keep GPS RTC alive for faster fix on wake
+  digitalWrite(GPS_RTC_INT, LOW);    // make sure this is LOW so we can pulse it to wake
+  airohaEnterSleep(_nmea);           // send command to put the GPS into RTC backup sleep
   digitalWrite(GPS_EN, LOW);
-  digitalWrite(GPS_RESET, HIGH);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
-  digitalWrite(GPS_RTC_INT, LOW);
-  pinMode(GPS_RESETB, OUTPUT);
-  digitalWrite(GPS_RESETB, LOW);
-  //_nmea->stop();
 }
 
 
 bool T1000SensorManager::begin() {
   // init GPS
   Serial1.begin(115200);
+  digitalWrite(GPS_RESET, HIGH);
+  delay(10);
+  digitalWrite(GPS_RESET, LOW);
   return true;
 }
 
@@ -156,7 +129,6 @@ void T1000SensorManager::loop() {
       node_lat = ((double)_nmea->getLatitude())/1000000.;
       node_lon = ((double)_nmea->getLongitude())/1000000.;
       node_altitude = ((double)_nmea->getAltitude()) / 1000.0;
-      //Serial.printf("lat %f lon %f\r\n", _lat, _lon);
     }
     next_gps_update = millis() + 1000;
   }
@@ -176,7 +148,7 @@ const char* T1000SensorManager::getSettingValue(int i) const {
 bool T1000SensorManager::setSettingValue(const char* name, const char* value) {
   if (strcmp(name, "gps") == 0) {
     if (strcmp(value, "0") == 0) {
-      sleep_gps(); // sleep for faster fix !
+      stop_gps();
     } else {
       start_gps();
     }

variants/t1000-e/variant.cpp

@@ -71,7 +71,7 @@ void initVariant()
   pinMode(LUX_SENSOR, INPUT);
   pinMode(EXT_CHRG_DETECT, INPUT);
   pinMode(EXT_PWR_DETECT, INPUT);
-  pinMode(GPS_RESETB, INPUT);
+  pinMode(GPS_RESETB, INPUT_PULLUP);
   pinMode(PIN_BUTTON1, INPUT);
 
   pinMode(PIN_3V3_EN, OUTPUT);
@@ -89,10 +89,10 @@ void initVariant()
   digitalWrite(PIN_3V3_ACC_EN, LOW);
   digitalWrite(BUZZER_EN, LOW);
   digitalWrite(SENSOR_EN, LOW);
-  digitalWrite(GPS_EN, LOW);
+  digitalWrite(GPS_EN, HIGH);
   digitalWrite(GPS_RESET, LOW);
-  digitalWrite(GPS_VRTC_EN, LOW);
-  digitalWrite(GPS_SLEEP_INT, HIGH);
+  digitalWrite(GPS_VRTC_EN, HIGH);
+  digitalWrite(GPS_SLEEP_INT, LOW);
   digitalWrite(GPS_RTC_INT, LOW);
   digitalWrite(LED_PIN, LOW);
 }