GPS: short update intervals, lock-time prediction (#4070)

* Refactor GPSPowerState enum
Identifies a case where the GPS hardware is awake, but an update is not yet desired

* Change terminology

* Clear old lock-time prediction on triple press

* Use exponential smoothing to predict lock time

* Rename averageLockTime to predictedLockTime

* Attempt: Send PMREQ with duration 0 on MCU deep-sleep

* Attempt 2: Send PMREQ with duration 0 on MCU deep-sleep

* Revert "Attempt 2: Send PMREQ with duration 0 on MCU deep-sleep"

This reverts commit 8b697cd2a4.

* Revert "Attempt: Send PMREQ with duration 0 on MCU deep-sleep"

This reverts commit 9d29ec7603.
This commit is contained in:
todd-herbert 2024-06-15 01:28:01 +12:00 committed by GitHub
parent 16b41b51af
commit 39c9f92c6e
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2 changed files with 71 additions and 37 deletions

View File

@ -28,6 +28,12 @@
#define GPS_STANDBY_THRESHOLD_MINUTES 15
#endif
// How many seconds of sleep make it worthwhile for the GPS to use powered-on standby
// Shorter than this, and we'll just wait instead
#ifndef GPS_IDLE_THRESHOLD_SECONDS
#define GPS_IDLE_THRESHOLD_SECONDS 10
#endif
#if defined(NRF52840_XXAA) || defined(NRF52833_XXAA) || defined(ARCH_ESP32) || defined(ARCH_PORTDUINO)
HardwareSerial *GPS::_serial_gps = &Serial1;
#else
@ -776,14 +782,22 @@ void GPS::setGPSPower(bool on, bool standbyOnly, uint32_t sleepTime)
{
// Record the current powerState
if (on)
powerState = GPS_AWAKE;
else if (!on && standbyOnly)
powerState = GPS_ACTIVE;
else if (!enabled) // User has disabled with triple press
powerState = GPS_OFF;
else if (sleepTime <= GPS_IDLE_THRESHOLD_SECONDS * 1000UL)
powerState = GPS_IDLE;
else if (standbyOnly)
powerState = GPS_STANDBY;
else
powerState = GPS_OFF;
LOG_DEBUG("GPS::powerState=%d\n", powerState);
// If the next update is due *really soon*, don't actually power off or enter standby. Just wait it out.
if (!on && powerState == GPS_IDLE)
return;
if (on) {
clearBuffer(); // drop any old data waiting in the buffer before re-enabling
if (en_gpio)
@ -880,54 +894,69 @@ void GPS::setConnected()
void GPS::setAwake(bool wantAwake)
{
// If user has disabled GPS, make sure it is off, not just in standby
// If user has disabled GPS, make sure it is off, not just in standby or idle
if (!wantAwake && !enabled && powerState != GPS_OFF) {
setGPSPower(false, false, 0);
return;
}
// If GPS power state needs to change
if ((wantAwake && powerState != GPS_AWAKE) || (!wantAwake && powerState == GPS_AWAKE)) {
if ((wantAwake && powerState != GPS_ACTIVE) || (!wantAwake && powerState == GPS_ACTIVE)) {
LOG_DEBUG("WANT GPS=%d\n", wantAwake);
// Calculate how long it takes to get a GPS lock
if (wantAwake) {
// Record the time we start looking for a lock
lastWakeStartMsec = millis();
} else {
// Record by how much we missed our ideal target postion.gps_update_interval (for logging only)
// Need to calculate this before we update lastSleepStartMsec, to make the new prediction
int32_t lateByMsec = (int32_t)(millis() - lastSleepStartMsec) - (int32_t)getSleepTime();
// Record the time we finish looking for a lock
lastSleepStartMsec = millis();
if (GPSCycles == 1) { // Skipping initial lock time, as it will likely be much longer than average
averageLockTime = lastSleepStartMsec - lastWakeStartMsec;
} else if (GPSCycles > 1) {
averageLockTime += ((int32_t)(lastSleepStartMsec - lastWakeStartMsec) - averageLockTime) / (int32_t)GPSCycles;
// How long did it take to get GPS lock this time?
uint32_t lockTime = lastSleepStartMsec - lastWakeStartMsec;
// Update the lock-time prediction
// Used pre-emptively, attempting to hit target of gps.position_update_interval
switch (GPSCycles) {
case 0:
LOG_DEBUG("Initial GPS lock took %ds\n", lockTime / 1000);
break;
case 1:
predictedLockTime = lockTime; // Avoid slow ramp-up - start with a real value
LOG_DEBUG("GPS Lock took %ds\n", lockTime / 1000);
break;
default:
// Predict lock-time using exponential smoothing: respond slowly to changes
predictedLockTime = (lockTime * 0.2) + (predictedLockTime * 0.8); // Latest lock time has 20% weight on prediction
LOG_INFO("GPS Lock took %ds. %s by %ds. Next lock predicted to take %ds.\n", lockTime / 1000,
(lateByMsec > 0) ? "Late" : "Early", abs(lateByMsec) / 1000, predictedLockTime / 1000);
}
GPSCycles++;
LOG_DEBUG("GPS Lock took %d, average %d\n", (lastSleepStartMsec - lastWakeStartMsec) / 1000, averageLockTime / 1000);
}
// How long to wait before attempting next GPS update
// Aims to hit position.gps_update_interval by using the lock-time prediction
uint32_t compensatedSleepTime = (getSleepTime() > predictedLockTime) ? (getSleepTime() - predictedLockTime) : 0;
// If long interval between updates: power off between updates
if ((int32_t)getSleepTime() - averageLockTime > GPS_STANDBY_THRESHOLD_MINUTES * MS_IN_MINUTE) {
setGPSPower(wantAwake, false, getSleepTime() - averageLockTime);
return;
if (compensatedSleepTime > GPS_STANDBY_THRESHOLD_MINUTES * MS_IN_MINUTE) {
setGPSPower(wantAwake, false, getSleepTime() - predictedLockTime);
}
// If waking frequently: standby only. Would use more power trying to reacquire lock each time
else if ((int32_t)getSleepTime() - averageLockTime > 10000) { // 10 seconds is enough for standby
// If waking relatively frequently: don't power off. Would use more energy trying to reacquire lock each time
// We'll either use a "powered-on" standby, or just wait it out, depending on how soon the next update is due
// Will decide which inside setGPSPower method
else {
#ifdef GPS_UC6580
setGPSPower(wantAwake, false, getSleepTime() - averageLockTime);
setGPSPower(wantAwake, false, compensatedSleepTime);
#else
setGPSPower(wantAwake, true, getSleepTime() - averageLockTime);
setGPSPower(wantAwake, true, compensatedSleepTime);
#endif
return;
}
// Gradually recover from an abnormally long "time to get lock"
if (averageLockTime > 20000) {
averageLockTime -= 1000; // eventually want to sleep again.
}
// Make sure we don't have a fallthrough where GPS is stuck off
if (wantAwake)
setGPSPower(true, true, 0);
}
}
@ -1033,14 +1062,14 @@ int32_t GPS::runOnce()
uint32_t timeAsleep = now - lastSleepStartMsec;
auto sleepTime = getSleepTime();
if (powerState != GPS_AWAKE && (sleepTime != UINT32_MAX) &&
((timeAsleep > sleepTime) || (isInPowersave && timeAsleep > (sleepTime - averageLockTime)))) {
if (powerState != GPS_ACTIVE && (sleepTime != UINT32_MAX) &&
((timeAsleep > sleepTime) || (isInPowersave && timeAsleep > (sleepTime - predictedLockTime)))) {
// We now want to be awake - so wake up the GPS
setAwake(true);
}
// While we are awake
if (powerState == GPS_AWAKE) {
if (powerState == GPS_ACTIVE) {
// LOG_DEBUG("looking for location\n");
// If we've already set time from the GPS, no need to ask the GPS
bool gotTime = (getRTCQuality() >= RTCQualityGPS);
@ -1086,7 +1115,7 @@ int32_t GPS::runOnce()
// 9600bps is approx 1 byte per msec, so considering our buffer size we never need to wake more often than 200ms
// if not awake we can run super infrquently (once every 5 secs?) to see if we need to wake.
return (powerState == GPS_AWAKE) ? GPS_THREAD_INTERVAL : 5000;
return (powerState == GPS_ACTIVE) ? GPS_THREAD_INTERVAL : 5000;
}
// clear the GPS rx buffer as quickly as possible
@ -1617,9 +1646,9 @@ bool GPS::whileIdle()
{
unsigned int charsInBuf = 0;
bool isValid = false;
if (powerState != GPS_AWAKE) {
if (powerState != GPS_ACTIVE) {
clearBuffer();
return (powerState == GPS_AWAKE);
return (powerState == GPS_ACTIVE);
}
#ifdef SERIAL_BUFFER_SIZE
if (_serial_gps->available() >= SERIAL_BUFFER_SIZE - 1) {
@ -1650,6 +1679,10 @@ bool GPS::whileIdle()
}
void GPS::enable()
{
// Clear the old lock-time prediction
GPSCycles = 0;
predictedLockTime = 0;
enabled = true;
setInterval(GPS_THREAD_INTERVAL);
setAwake(true);

View File

@ -39,9 +39,10 @@ typedef enum {
} GPS_RESPONSE;
enum GPSPowerState : uint8_t {
GPS_OFF = 0,
GPS_AWAKE = 1,
GPS_STANDBY = 2,
GPS_OFF = 0, // Physically powered off
GPS_ACTIVE = 1, // Awake and want a position
GPS_STANDBY = 2, // Physically powered on, but soft-sleeping
GPS_IDLE = 3, // Awake, but not wanting another position yet
};
// Generate a string representation of DOP
@ -72,7 +73,7 @@ class GPS : private concurrency::OSThread
uint32_t rx_gpio = 0;
uint32_t tx_gpio = 0;
uint32_t en_gpio = 0;
int32_t averageLockTime = 0;
int32_t predictedLockTime = 0;
uint32_t GPSCycles = 0;
int speedSelect = 0;
@ -93,7 +94,7 @@ class GPS : private concurrency::OSThread
bool GPSInitFinished = false; // Init thread finished?
bool GPSInitStarted = false; // Init thread finished?
GPSPowerState powerState = GPS_OFF; // GPS_AWAKE if we want a location right now
GPSPowerState powerState = GPS_OFF; // GPS_ACTIVE if we want a location right now
uint8_t numSatellites = 0;