RAK3401: powerOff() override + AIN1 SENSE LOW wake from SYSTEMOFF 🤖🤖

src/helpers/NRF52Board.cpp

@@ -177,7 +177,7 @@ void NRF52Board::enterSystemOff(uint8_t reason) {
   NVIC_SystemReset();
 }
 
-void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel) {
+void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel, bool detect_down) {
   // LPCOMP is not managed by SoftDevice - direct register access required
   // Halt and disable before reconfiguration
   NRF_LPCOMP->TASKS_STOP = 1;
@@ -189,8 +189,10 @@ void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel) {
   // Reference: REFSEL (0-6=1/8..7/8, 7=ARef, 8-15=1/16..15/16)
   NRF_LPCOMP->REFSEL = ((uint32_t)refsel << LPCOMP_REFSEL_REFSEL_Pos) & LPCOMP_REFSEL_REFSEL_Msk;
 
-  // Detect UP events (voltage rises above threshold for battery recovery)
-  NRF_LPCOMP->ANADETECT = LPCOMP_ANADETECT_ANADETECT_Up;
+  // Crossing direction: UP for voltage recovery (rises above threshold),
+  // DOWN for an analog button press (pin pulled below threshold).
+  NRF_LPCOMP->ANADETECT = detect_down ? LPCOMP_ANADETECT_ANADETECT_Down
+                                      : LPCOMP_ANADETECT_ANADETECT_Up;
 
   // Enable 50mV hysteresis for noise immunity
   NRF_LPCOMP->HYST = LPCOMP_HYST_HYST_Hyst50mV;
@@ -202,7 +204,7 @@ void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel) {
   NRF_LPCOMP->EVENTS_CROSS = 0;
 
   NRF_LPCOMP->INTENCLR = 0xFFFFFFFF;
-  NRF_LPCOMP->INTENSET = LPCOMP_INTENSET_UP_Msk;
+  NRF_LPCOMP->INTENSET = detect_down ? LPCOMP_INTENSET_DOWN_Msk : LPCOMP_INTENSET_UP_Msk;
 
   // Enable LPCOMP
   NRF_LPCOMP->ENABLE = LPCOMP_ENABLE_ENABLE_Enabled;

src/helpers/NRF52Board.h

@@ -40,7 +40,10 @@ class NRF52Board : public mesh::MainBoard {
 
   bool checkBootVoltage(const PowerMgtConfig* config);
   void enterSystemOff(uint8_t reason);
-  void configureVoltageWake(uint8_t ain_channel, uint8_t refsel);
+  // Arm LPCOMP as a SYSTEMOFF wake source on the given analog channel.
+  // detect_down=false wakes on an upward crossing (voltage recovery);
+  // detect_down=true wakes on a downward crossing (e.g. an analog button press).
+  void configureVoltageWake(uint8_t ain_channel, uint8_t refsel, bool detect_down = false);
   virtual void initiateShutdown(uint8_t reason);
 #endif
 

variants/rak3401/RAK3401Board.cpp

@@ -4,6 +4,17 @@
 #include "RAK3401Board.h"
 
 #ifdef NRF52_POWER_MANAGEMENT
+#ifdef PIN_USER_BTN_ANA
+// LPCOMP wake config for the AIN user button. Defaults assume PIN_USER_BTN_ANA
+// is pin 31 (P0.31 = AIN7); override via build flags if the button moves.
+#ifndef PWRMGT_BTN_LPCOMP_AIN
+  #define PWRMGT_BTN_LPCOMP_AIN 7
+#endif
+#ifndef PWRMGT_BTN_LPCOMP_REFSEL
+  #define PWRMGT_BTN_LPCOMP_REFSEL 3   // 4/8 VDD (~1.5V) threshold
+#endif
+#endif
+
 // Static configuration for power management
 // Values set in variant.h defines
 const PowerMgtConfig power_config = {
@@ -24,6 +35,37 @@ void RAK3401Board::initiateShutdown(uint8_t reason) {
     configureVoltageWake(power_config.lpcomp_ain_channel, power_config.lpcomp_refsel);
   }
 
+#ifdef PIN_USER_BTN_ANA
+  // Wake-from-SYSTEMOFF on the AIN user button (P0.31 = AIN7).
+  //
+  // This pin is wired as an *analog* button (see MomentaryButton in target.cpp:
+  // pressed == analogRead() < threshold). GPIO SENSE can't be used as the wake
+  // source: the digital input buffer reads this line as LOW even at the released
+  // idle level (verified on hardware — analogRead reports ~VDD while NRF_GPIO->IN
+  // reads 0 and SENSE_Low latches immediately), so a GPIO SENSE arm wakes the
+  // chip the instant we enter SYSTEMOFF and it can never stay off.
+  //
+  // LPCOMP works in the analog domain, so it sees the idle level correctly. Arm
+  // it for a DOWN crossing at ~1/2 VDD: released idles near VDD (above), a press
+  // pulls the pin toward 0V (below) -> downward crossing -> wake. The LPCOMP is
+  // otherwise unused for a USER shutdown (voltage wake is only armed for the
+  // low-voltage / boot-protect reasons handled above), so there is no conflict.
+  //
+  // Wait for release first so LPCOMP is armed while the level is above the
+  // threshold — otherwise the initial press generates no new downward crossing.
+  // Bounded by a timeout so a stuck/low reading can never wedge shutdown.
+  const int BTN_RELEASED_ADC = 1024;  // well above the press threshold
+  uint32_t t0 = millis();
+  int released_streak = 0;
+  while (released_streak < 5 && (millis() - t0) < 5000) {
+    if (analogRead(PIN_USER_BTN_ANA) > BTN_RELEASED_ADC) released_streak++;
+    else released_streak = 0;
+    delay(10);
+  }
+
+  configureVoltageWake(PWRMGT_BTN_LPCOMP_AIN, PWRMGT_BTN_LPCOMP_REFSEL, /*detect_down=*/true);
+#endif
+
   enterSystemOff(reason);
 }
 #endif

variants/rak3401/RAK3401Board.h

@@ -20,6 +20,10 @@ class RAK3401Board : public NRF52BoardDCDC {
   RAK3401Board() : NRF52Board("RAK3401_OTA") {}
   void begin();
 
+#ifdef NRF52_POWER_MANAGEMENT
+  void powerOff() override { initiateShutdown(SHUTDOWN_REASON_USER); }
+#endif
+
   #define BATTERY_SAMPLES 8
 
   uint16_t getBattMilliVolts() override {