Power off ThinkNode M3: wake on button, cut peripheral rails

The long press already reached board.powerOff(), but nothing armed a wake
source, so the board stayed dead until a reset or a USB reconnect. Arm the
user button (pull-up + SENSE_LOW) before entering SYSTEMOFF, after waiting
for the release: SENSE is level triggered and a still pressed button wakes
the board up immediately. If the button is never released, reboot instead:
SYSTEMOFF would wake up right away anyway, so make the reset explicit.

GPIO output latches survive SYSTEMOFF, so shut the switched rails down as
well (GNSS, RGB led supply, EEPROM, battery divider, EN1/EN2, PWR_EN), in a
shutdownPeripherals() override so they go down after the radio and the GNSS
receiver. Give pins 36 and 34 a name while there.

Tested on a ThinkNode M3 companion_radio_ble: a long press powers the board
off (the USB device disappears and stays away), a short press brings it
back, and holding the button past the timeout reboots.

variants/thinknode_m3/ThinkNodeM3Board.cpp

@@ -13,6 +13,42 @@ void ThinkNodeM3Board::begin() {
   delay(10);   // give sx1262 some time to power up
 }
 
+void ThinkNodeM3Board::shutdownPeripherals() {
+  NRF52Board::shutdownPeripherals();   // display, LoRa radio and GNSS receiver
+
+  // GPIO output latches survive SYSTEMOFF, so every switched rail still enabled
+  // here keeps draining the battery while the board looks powered off
+  digitalWrite(PIN_GPS_POWER, !GPS_POWER_ACTIVE);
+  digitalWrite(LED_POWER, LOW);     // RGB led supply
+  digitalWrite(EEPROM_POWER, LOW);
+  digitalWrite(BAT_POWER, LOW);     // battery voltage divider
+  digitalWrite(PIN_EN1, LOW);
+  digitalWrite(PIN_EN2, LOW);
+  digitalWrite(PIN_PWR_EN, LOW);
+}
+
+void ThinkNodeM3Board::powerOff() {
+  // turn off all leds, sd_power_system_off will not do this for us
+  digitalWrite(PIN_LED_BLUE, !LED_STATE_ON);
+  digitalWrite(PIN_LED_GREEN, !LED_STATE_ON);
+  digitalWrite(PIN_LED_RED, !LED_STATE_ON);
+
+  // the button is what powers the board back on, and SENSE is level triggered:
+  // wait for the release, or the board wakes up as soon as it goes SYSTEMOFF
+  uint32_t started_at = millis();
+  while (digitalRead(BUTTON_PIN) == LOW) {
+    if (millis() - started_at > 10000) {   // button held down for too long, or stuck:
+      reboot();                            // SYSTEMOFF would wake up right away anyway
+    }
+    delay(10);
+  }
+  delay(50);   // debounce the release
+  nrf_gpio_cfg_sense_input(g_ADigitalPinMap[BUTTON_PIN], NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);
+
+  // power off board
+  NRF52Board::powerOff();
+}
+
 uint16_t ThinkNodeM3Board::getBattMilliVolts() {
   int adcvalue = 0;
 

variants/thinknode_m3/ThinkNodeM3Board.h

@@ -42,13 +42,6 @@ public:
     return 0;
   }
 
-  void powerOff() override {
-    // turn off all leds, sd_power_system_off will not do this for us
-    digitalWrite(PIN_LED_BLUE, !LED_STATE_ON);
-    digitalWrite(PIN_LED_GREEN, !LED_STATE_ON);
-    digitalWrite(PIN_LED_RED, !LED_STATE_ON);
-
-    // power off board
-    NRF52Board::powerOff();
-  }
+  void shutdownPeripherals() override;
+  void powerOff() override;
 };

variants/thinknode_m3/variant.cpp

@@ -71,10 +71,10 @@ void initVariant()
   pinMode(EEPROM_POWER, OUTPUT);
   digitalWrite(EEPROM_POWER, HIGH);
 
-  pinMode(36, OUTPUT);
-  digitalWrite(36, HIGH);
-  pinMode(34, OUTPUT);
-  digitalWrite(34, HIGH);
+  pinMode(PIN_EN1, OUTPUT);
+  digitalWrite(PIN_EN1, HIGH);
+  pinMode(PIN_EN2, OUTPUT);
+  digitalWrite(PIN_EN2, HIGH);
 
   pinMode(LED_POWER, OUTPUT);
   digitalWrite(LED_POWER, HIGH);

variants/thinknode_m3/variant.h

@@ -42,6 +42,8 @@
 #define EEPROM_POWER            (7)
 #define BAT_POWER               (17)
 #define PIN_PWR_EN              (16)
+#define PIN_EN1                 (36)            // P1.4, buzzer supply
+#define PIN_EN2                 (34)            // P1.2
 
 
 ////////////////////////////////////////////////////////////////////////////////