Use wake up pin that is not dependent on analog power

.github/workflows/arduino-lint.yml

@@ -22,7 +22,7 @@ jobs:
         uses: arduino/arduino-lint-action@v1
         with:
           compliance: specification
-          library-manager: submit
+          library-manager: update
           # Always use this setting for official repositories. Remove for 3rd party projects.
           official: true
           project-type: library

examples/WakeFromPin/WakeFromPin.ino

@@ -19,7 +19,12 @@
 * - Select the Portenta C33's USB port from the Tools menu
 * - Upload the code to your Portenta C33
 * - Connect a button to pin D0 and ground with a pull-up resistor to 3.3V
-* - Connect a button to pin A3 and ground with a pull-up resistor to 3.3V 
+* - Connect a button to pin D4 and ground with a pull-up resistor to 3.3V 
+*   
+*   For maximum power saving use external pull-up resistors.
+*   You will need to power them separately as the 3.3V pin on the board 
+*   is turned off when the device goes to sleep and TURN_PERIPHERALS_OFF is enabled.
+*   Alternatively, use pinMode(<pin>, INPUT_PULLUP) for the pins and connect the buttons to ground.
 * (If you need information about how to wire the buttons check this link: https://docs.arduino.cc/built-in-examples/digital/Button/)
 * 
 * Initial author: C. Dragomir
@@ -29,9 +34,17 @@
 
 // #define TURN_PERIPHERALS_OFF // Uncomment this line to turn off the peripherals before going to sleep
 #define SLEEP_PIN D0 // Pin used to put the device to sleep
-#define WAKE_PIN A3 // Pin used to wake up the device
+
+/*
+The following pins can be used to wake up the device: A0, A1, A2, A3, A4, A5, D4, D7
+However turnPeripheralsOff() in this sketch turns off the power lane of the analog pins.
+This means they cannot sink current and therefore cannot be used to wake up the device. 
+Hency only D4 and D7 can be used to wake up the device in this configuration.
+*/
+#define WAKE_PIN D4
 
 LowPower lowPower;
+bool shouldSleep = false;
 
 #ifdef TURN_PERIPHERALS_OFF
     #include "Arduino_PMIC.h"
@@ -56,17 +69,11 @@ LowPower lowPower;
 #endif
 
 void goToSleep(){
-    // Turn off the built-in LED before going to sleep
-    digitalWrite(LED_BUILTIN, HIGH);
-
-    #ifdef TURN_PERIPHERALS_OFF
-        turnPeripheralsOff();
-    #endif
-    lowPower.deepSleep(); 
+    shouldSleep = true;
 }
 
 void setup(){
-    // External pull-up resistor used for the buttons
+    // External pull-up resistor used for the buttons for maximum power saving
     pinMode(SLEEP_PIN, INPUT);
     pinMode(WAKE_PIN, INPUT);
 
@@ -83,6 +90,17 @@ void setup(){
 }
 
 void loop(){
+    if(shouldSleep){
+        // Turn off the built-in LED before going to sleep
+        digitalWrite(LED_BUILTIN, HIGH);
+
+        #ifdef TURN_PERIPHERALS_OFF
+            turnPeripheralsOff();
+        #endif
+        lowPower.deepSleep(); 
+        shouldSleep = false;
+    }
+
     // Blink the built-in LED every 500ms when the device is not sleeping    
     digitalWrite(LED_BUILTIN, LOW);
     delay(500);