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Fix GPS UART consuming +8mA when disabled (nRF52) #1633

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Fix GPS UART consuming +8mA when disabled (nRF52) #1633

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b9eb9a3
Fix GPS UART consuming +8mA when disabled (nRF52)
weebl2000 Feb 8, 2026
59f341c
Fix Serial1.end() hang on nRF52: pull up RX before UART shutdown
weebl2000 Feb 8, 2026
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20 changes: 19 additions & 1 deletion src/helpers/sensors/EnvironmentSensorManager.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -583,6 +583,11 @@ void EnvironmentSensorManager::initBasicGPS() {
MESH_DEBUG_PRINTLN("No GPS detected");
}
_location->stop();
// Pull up MCU's RX pin before ending UART. When GPS powers down, its TX
// line drops LOW (break condition) which prevents nRF52 UARTE's RXTO event
// from firing, causing Serial1.end() to hang indefinitely.
pinMode(PIN_GPS_TX, INPUT_PULLUP); // PIN_GPS_TX = toward CPU = MCU's RX
Serial1.end(); // Disable UART peripheral to save power (significant on nRF52)
gps_active = false; //Set GPS visibility off until setting is changed
}

Expand Down Expand Up @@ -680,6 +685,14 @@ void EnvironmentSensorManager::start_gps() {
return;
#endif

// Re-initialize UART (was closed by stop_gps() to save power)
Serial1.setPins(PIN_GPS_TX, PIN_GPS_RX);
#ifdef GPS_BAUD_RATE
Serial1.begin(GPS_BAUD_RATE);
#else
Serial1.begin(9600);
#endif

_location->begin();
_location->reset();

Expand All @@ -697,6 +710,9 @@ void EnvironmentSensorManager::stop_gps() {
#endif

_location->stop();
// Pull up MCU's RX pin before ending UART - see comment in initBasicGPS()
pinMode(PIN_GPS_TX, INPUT_PULLUP);
Serial1.end(); // Disable UART peripheral to save power (significant on nRF52)

#ifndef PIN_GPS_EN
MESH_DEBUG_PRINTLN("Stop GPS is N/A on this board. Actual GPS state unchanged");
Expand All @@ -707,7 +723,9 @@ void EnvironmentSensorManager::loop() {
static long next_gps_update = 0;

#if ENV_INCLUDE_GPS
_location->loop();
if (gps_active) {
_location->loop();
}
if (millis() > next_gps_update) {

if(gps_active){
Expand Down