Help me understand how to use Low Power library?

Other Hardware 3rd Party Boards
1

Hi! I'm trying to learn how to use the sleep mode on SAMD board (Nano IoT). The problem I have is that I can't find enough example sketches on Google that work with the IoT and the only documentation I depend on is the one from Arduino page, which is not very thorough.

Anyway, here is my current sketch:

#include <ArduinoLowPower.h>

void setup() {
pinMode(3, INPUT_PULLUP); //Pin 3.
pinMode(LED_BUILTIN, OUTPUT);
digitalWrite(LED_BUILTIN, HIGH);
LowPower.attachInterruptWakeup(3, loop, CHANGE);
}

void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay (10000);

goSleep();
}

void goSleep() {
digitalWrite(LED_BUILTIN, LOW);
LowPower.sleep();
}

At the moment, how it's working is the Arduino goes to sleep after second. When I ground the Pin 3, the LED turns on and quickly turns off right away -- but the Arduino stays on sleep mode.

Also with this, as I understand:

LowPower.attachInterruptWakeup(3, loop, CHANGE);

The "CHANGE" means like a change in the value of the pin? Is CHANGE used for sensors like LDR?

And for the "loop" part, is there a way I can resume the Arduino doing it's last job before going to sleep instead of resetting it to loop()?

Also can you please show me a very basic example of the low power sketch without calling a function -- just waking up the Arduino and resuming its last state / job before sleeping? I think how I wrote this basic sketch is wrong since it's not even waking up from sleep.

2

So many questions, so little time, so I will just answer the first question. CHANGE is used for going from low to high or from high to low. Depending upon your LDR and how it is connected, this may or may not be true.