[AE-60] Fail_safe_sketch.ino has an identity crisis

[aliphys]

Describe the Problem

The Fail_safe_sketch.ino sketch is provided as an example sketch for the bootloader.

• What is the purpose to changing the values of P0_17 and P0_19?

  • nicla-sense-me-fw/bootloader/examples/Fail_safe_sketch/Fail_safe_sketch.ino

    Lines 9 to 16 in 098b8e0

    	for (int i = 0; i<3; i++) {
    	digitalWrite(P0_17, LOW);
    	digitalWrite(P0_19, HIGH);
    	delay(500);
    	digitalWrite(P0_17, HIGH);
    	digitalWrite(P0_19, LOW);
    	delay(500);
    	}

• Nothing happens when you upload the sketch, nor is it clear what is supposed to happen.

To reproduce

Upload Fail_safe_sketch.ino to board

Expected behaviour

• Something noticable happens when sketch is uploaded
• There is a link between the bootloader and this sketch (or else is moved elsewhere)
• A description is provided as to the role of this sketch

Arduino CLI version

0.32.3 - arduino/arduino-cli@2661f5d

Operating system

Ubuntu 22.04.2 LTS

Additional Context

• According to variant.cpp and Nicla Sense ME Pinout, P0_19 is the INT pin on the ESLOV interface. I cannot find P0_17 (checked Altium/Pinout) for the Nicla Sense ME.
  • https://github.com/arduino/ArduinoCore-mbed/blob/e594a0eb585a2daf1fd5a110428e8a20d28f9ab6/variants/NICLA/variant.cpp#L90
  • 
• No pins are pulled high

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Thanks @marqdevx and @Hannes7eicher for suggestions