nRF52840 Power Management Stage 1 (Boot Lock) - v2.3 preparation work

This commit lays some of the ground work for the upcoming power management fix that allows users to configure the boot lock behaviour.

It is *not* the full fix yet. The goal is to break up the larger commit into smaller chunks so it is easier to review and softer to merge.

Improvements:
- MainBoard: Add bool to check if power management has been initialised (later to be consumed by CommonCLI to validate we can safely configure the settings)
- MainBoard: Add bool to validate LPCOMP is supported on the board (gates LPCOMP config so it doesnt wedge on an unsupported board)
- NRF52Board: Rename initPowerMgr() -> pwrmgtInit() to align with the "pwrmgt" prefix being used by any power management related functions in the upcoming new version
- NRF52Board: Add a shutdown reason for "None" so the `get pwrmgt.bootreason` command doesnt erroneously return "Unknown"
- NRF52Board: Add gate in configureVoltageWake to not arm LPCOMP when power management isn't initialised or the board doesn't support LPCOMP (i.e. we havent defined the AIN pin)
- NRF52Board: Reference the LPCOMP AIN pin directly instead of from the per-board definitions to align to the upcoming deprecation of the per-board static configs
- NRF52Board: Drop LPCOMP hysteresis as it broadens the wake voltage too much and makes the board less likely to self-recover
- NRF52Board: Separate LPCOMP and VBUS wake arm into their own functions

src/MeshCore.h

@@ -69,8 +69,10 @@ public:
   virtual bool isLoRaFemLnaEnabled() const { return false; }
 
   // Power management interface (boards with power management override these)
+  virtual bool isPwrMgtInitialised() const { return false; }
   virtual bool isExternalPowered() { return false; }
   virtual uint16_t getBootVoltage() { return 0; }
+  virtual bool getWakeLpcompSupported() const { return false; }
   virtual uint32_t getResetReason() const { return 0; }
   virtual const char* getResetReasonString(uint32_t reason) { return "Not available"; }
   virtual uint8_t getShutdownReason() const { return 0; }

src/helpers/NRF52Board.cpp

@@ -38,7 +38,8 @@ static void __attribute__((constructor(101))) nrf52_early_reset_capture() {
   g_nrf52_shutdown_reason = NRF_POWER->GPREGRET2;
 }
 
-void NRF52Board::initPowerMgr() {
+void NRF52Board::pwrmgtInit() {
+  if (pwrmgt_initialised) return;
   // Copy early-captured register values
   reset_reason = g_nrf52_reset_reason;
   shutdown_reason = g_nrf52_shutdown_reason;
@@ -65,6 +66,7 @@ void NRF52Board::initPowerMgr() {
     MESH_DEBUG_PRINTLN("PWRMGT: Reset = %s (0x%lX)",
       getResetReasonString(reset_reason), (unsigned long)reset_reason);
   }
+  pwrmgt_initialised = true;
 }
 
 const char* NRF52Board::getResetReasonString(uint32_t reason) {
@@ -89,6 +91,7 @@ const char* NRF52Board::getResetReasonString(uint32_t reason) {
 
 const char* NRF52Board::getShutdownReasonString(uint8_t reason) {
   switch (reason) {
+    case SHUTDOWN_REASON_NONE:         return "None";
     case SHUTDOWN_REASON_LOW_VOLTAGE:  return "Low Voltage";
     case SHUTDOWN_REASON_USER:         return "User Request";
     case SHUTDOWN_REASON_BOOT_PROTECT: return "Boot Protection";
@@ -97,7 +100,7 @@ const char* NRF52Board::getShutdownReasonString(uint8_t reason) {
 }
 
 bool NRF52Board::checkBootVoltage(const PowerMgtConfig* config) {
-  initPowerMgr();
+  pwrmgtInit();
 
   // Read boot voltage
   boot_voltage_mv = getBattMilliVolts();
@@ -164,24 +167,30 @@ 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 lpcomp_refsel) {
+  pwrmgtWakeArmVbus();
+  if (!isPwrMgtInitialised()) {
+    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake not armed. Reason: Power Management not initialised");
+    return;
+  }
+  if (!getWakeLpcompSupported()) {
+    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake not armed. Reason: LPCOMP unsupported on variant");
+    return;
+  }
   // LPCOMP is not managed by SoftDevice - direct register access required
   // Halt and disable before reconfiguration
   NRF_LPCOMP->TASKS_STOP = 1;
   NRF_LPCOMP->ENABLE = LPCOMP_ENABLE_ENABLE_Disabled;
 
   // Select analog input (AIN0-7 maps to PSEL 0-7)
-  NRF_LPCOMP->PSEL = ((uint32_t)ain_channel << LPCOMP_PSEL_PSEL_Pos) & LPCOMP_PSEL_PSEL_Msk;
+  NRF_LPCOMP->PSEL = ((uint32_t)PWRMGT_LPCOMP_AIN << LPCOMP_PSEL_PSEL_Pos) & LPCOMP_PSEL_PSEL_Msk;
 
   // 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;
+  NRF_LPCOMP->REFSEL = ((uint32_t)lpcomp_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;
 
-  // Enable 50mV hysteresis for noise immunity
-  NRF_LPCOMP->HYST = LPCOMP_HYST_HYST_Hyst50mV;
-
   // Clear stale events/interrupts before enabling wake
   NRF_LPCOMP->EVENTS_READY = 0;
   NRF_LPCOMP->EVENTS_DOWN = 0;
@@ -195,23 +204,22 @@ void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel) {
   NRF_LPCOMP->ENABLE = LPCOMP_ENABLE_ENABLE_Enabled;
   NRF_LPCOMP->TASKS_START = 1;
 
-  // Wait for comparator to settle before entering SYSTEMOFF
+  // Wait for comparator to settle
   for (uint8_t i = 0; i < 20 && !NRF_LPCOMP->EVENTS_READY; i++) {
     delayMicroseconds(50);
   }
 
-  if (refsel == 7) {
+  if (lpcomp_refsel == 7) {
-    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake configured (AIN%d, ref=ARef)", ain_channel);
+    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake armed (AIN%d, ref=ARef)", PWRMGT_LPCOMP_AIN);
-  } else if (refsel <= 6) {
+  } else if (lpcomp_refsel <= 6) {
-    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake configured (AIN%d, ref=%d/8 VDD)",
+    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake armed (AIN%d, ref=%d/8 VDD)", PWRMGT_LPCOMP_AIN, lpcomp_refsel + 1);
-      ain_channel, refsel + 1);
   } else {
-    uint8_t ref_num = (uint8_t)((refsel - 8) * 2 + 1);
+    uint8_t ref_num = (uint8_t)((lpcomp_refsel - 8) * 2 + 1);
-    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake configured (AIN%d, ref=%d/16 VDD)",
+    MESH_DEBUG_PRINTLN("PWRMGT: LPCOMP wake armed (AIN%d, ref=%d/16 VDD)", PWRMGT_LPCOMP_AIN, ref_num);
-      ain_channel, ref_num);
   }
+}
 
-  // Configure VBUS (USB power) wake alongside LPCOMP
+void NRF52Board::pwrmgtWakeArmVbus() {
   uint8_t sd_enabled = 0;
   sd_softdevice_is_enabled(&sd_enabled);
   if (sd_enabled) {
@@ -220,8 +228,7 @@ void NRF52Board::configureVoltageWake(uint8_t ain_channel, uint8_t refsel) {
     NRF_POWER->EVENTS_USBDETECTED = 0;
     NRF_POWER->INTENSET = POWER_INTENSET_USBDETECTED_Msk;
   }
-
+  MESH_DEBUG_PRINTLN("PWRMGT: VBUS wake armed");
-  MESH_DEBUG_PRINTLN("PWRMGT: VBUS wake configured");
 }
 #endif
 

src/helpers/NRF52Board.h

@@ -25,15 +25,15 @@ struct PowerMgtConfig {
 #endif
 
 class NRF52Board : public mesh::MainBoard {
-#ifdef NRF52_POWER_MANAGEMENT
+private:
-  void initPowerMgr();
+  bool pwrmgt_initialised = false;
-#endif
 
 protected:
   uint8_t startup_reason;
   char *ota_name;
 
 #ifdef NRF52_POWER_MANAGEMENT
+  void pwrmgtInit();
   uint32_t reset_reason;              // RESETREAS register value
   uint8_t shutdown_reason;            // GPREGRET value (why we entered last SYSTEMOFF)
   uint16_t boot_voltage_mv;           // Battery voltage at boot (millivolts)
@@ -41,6 +41,7 @@ protected:
   bool checkBootVoltage(const PowerMgtConfig* config);
   void enterSystemOff(uint8_t reason);
   void configureVoltageWake(uint8_t ain_channel, uint8_t refsel);
+  void pwrmgtWakeArmVbus();
   virtual void initiateShutdown(uint8_t reason);
 #endif
 
@@ -63,6 +64,10 @@ public:
   uint8_t getShutdownReason() const override { return shutdown_reason; }
   const char* getResetReasonString(uint32_t reason) override;
   const char* getShutdownReasonString(uint8_t reason) override;
+  bool isPwrMgtInitialised() const override { return pwrmgt_initialised; }
+  #ifdef PWRMGT_LPCOMP_AIN
+    bool getWakeLpcompSupported() const override { return true; }
+  #endif
 #endif
 };