Merge branch 'dev' into nrf-dcdc

variants/xiao_nrf52/XiaoNrf52Board.cpp

@@ -5,12 +5,40 @@
 
 #include "XiaoNrf52Board.h"
 
+#ifdef NRF52_POWER_MANAGEMENT
+// Static configuration for power management
+// Values set in variant.h defines
+const PowerMgtConfig power_config = {
+  .lpcomp_ain_channel = PWRMGT_LPCOMP_AIN,
+  .lpcomp_refsel = PWRMGT_LPCOMP_REFSEL,
+  .voltage_bootlock = PWRMGT_VOLTAGE_BOOTLOCK
+};
+
+void XiaoNrf52Board::initiateShutdown(uint8_t reason) {
+  bool enable_lpcomp = (reason == SHUTDOWN_REASON_LOW_VOLTAGE ||
+                        reason == SHUTDOWN_REASON_BOOT_PROTECT);
+
+  pinMode(VBAT_ENABLE, OUTPUT);
+  digitalWrite(VBAT_ENABLE, enable_lpcomp ? LOW : HIGH);
+
+  if (enable_lpcomp) {
+    configureVoltageWake(power_config.lpcomp_ain_channel, power_config.lpcomp_refsel);
+  }
+
+  enterSystemOff(reason);
+}
+#endif // NRF52_POWER_MANAGEMENT
+
 void XiaoNrf52Board::begin() {
   NRF52BoardDCDC::begin();
 
+  // Configure battery voltage ADC
   pinMode(PIN_VBAT, INPUT);
   pinMode(VBAT_ENABLE, OUTPUT);
-  digitalWrite(VBAT_ENABLE, HIGH);
+  digitalWrite(VBAT_ENABLE, LOW);  // Enable VBAT divider for reading
+  analogReadResolution(12);
+  analogReference(AR_INTERNAL_3_0);
+  delay(50);  // Allow ADC to settle
 
 #ifdef PIN_USER_BTN
   pinMode(PIN_USER_BTN, INPUT_PULLUP);
@@ -27,9 +55,20 @@ void XiaoNrf52Board::begin() {
   digitalWrite(P_LORA_TX_LED, HIGH);
 #endif
 
-  //  pinMode(SX126X_POWER_EN, OUTPUT);
-  //  digitalWrite(SX126X_POWER_EN, HIGH);
-  delay(10); // give sx1262 some time to power up
+#ifdef NRF52_POWER_MANAGEMENT
+  // Boot voltage protection check (may not return if voltage too low)
+  checkBootVoltage(&power_config);
+#endif
+
+  delay(10);  // Give sx1262 some time to power up
+}
+
+uint16_t XiaoNrf52Board::getBattMilliVolts() {
+  // https://wiki.seeedstudio.com/XIAO_BLE#q3-what-are-the-considerations-when-using-xiao-nrf52840-sense-for-battery-charging
+  // VBAT_ENABLE must be LOW to read battery voltage
+  digitalWrite(VBAT_ENABLE, LOW);
+  int adcvalue = analogRead(PIN_VBAT);
+  return (adcvalue * ADC_MULTIPLIER * AREF_VOLTAGE) / 4.096;
 }
 
 #endif

variants/xiao_nrf52/XiaoNrf52Board.h

@@ -7,6 +7,11 @@
 #ifdef XIAO_NRF52
 
 class XiaoNrf52Board : public NRF52BoardDCDC {
+protected:
+#if NRF52_POWER_MANAGEMENT
+  void initiateShutdown(uint8_t reason) override;
+#endif
+
 public:
   XiaoNrf52Board() : NRF52Board("XIAO_NRF52_OTA") {}
   void begin();
@@ -20,21 +25,7 @@ public:
   }
 #endif
 
-  uint16_t getBattMilliVolts() override {
-    // Please read befor going further ;)
-    // https://wiki.seeedstudio.com/XIAO_BLE#q3-what-are-the-considerations-when-using-xiao-nrf52840-sense-for-battery-charging
-
-    // We can't drive VBAT_ENABLE to HIGH as long
-    // as we don't know wether we are charging or not ...
-    // this is a 3mA loss (4/1500)
-    digitalWrite(VBAT_ENABLE, LOW);
-    int adcvalue = 0;
-    analogReadResolution(12);
-    analogReference(AR_INTERNAL_3_0);
-    delay(10);
-    adcvalue = analogRead(PIN_VBAT);
-    return (adcvalue * ADC_MULTIPLIER * AREF_VOLTAGE) / 4.096;
-  }
+  uint16_t getBattMilliVolts() override;
 
   const char* getManufacturerName() const override {
     return "Seeed Xiao-nrf52";

variants/xiao_nrf52/platformio.ini

@@ -9,6 +9,7 @@ build_flags = ${nrf52_base.build_flags}
   -I variants/xiao_nrf52
   -UENV_INCLUDE_GPS
   -D NRF52_PLATFORM
+  -D NRF52_POWER_MANAGEMENT
   -D XIAO_NRF52
   -D RADIO_CLASS=CustomSX1262
   -D WRAPPER_CLASS=CustomSX1262Wrapper

variants/xiao_nrf52/variant.h

@@ -75,6 +75,21 @@ static const uint8_t D10 = 10;
 #define AREF_VOLTAGE            (3.0)
 #define ADC_MULTIPLIER          (3.0F) // 1M, 512k divider bridge
 
+// Power management boot protection threshold (millivolts)
+// Set to 0 to disable boot protection
+#define PWRMGT_VOLTAGE_BOOTLOCK    3300   // Won't boot below this voltage
+
+// LPCOMP wake configuration (voltage recovery from SYSTEMOFF)
+#define PWRMGT_LPCOMP_AIN           7     // AIN7 = P0.31 = PIN_VBAT
+// IMPORTANT: The XIAO exposes battery via a resistor divider (ADC_MULTIPLIER = 3.0).
+// LPCOMP measures the divided voltage, not the battery voltage directly.
+// Vpin = VDD * (REFSEL fraction), and VBAT ≈ Vpin * ADC_MULTIPLIER.
+//
+// Using 3/8 VDD gives a wake threshold above the boot protection point:
+// - If VDD ≈ 3.0V:  VBAT ≈ (3.0 * 3/8) * 3 ≈ 3375mV
+// - If VDD ≈ 3.3V:  VBAT ≈ (3.3 * 3/8) * 3 ≈ 3712mV
+#define PWRMGT_LPCOMP_REFSEL   2     // 3/8 VDD (~3.38-3.71V)
+
 static const uint8_t A0  = PIN_A0;
 static const uint8_t A1  = PIN_A1;
 static const uint8_t A2  = PIN_A2;