Exploring Sleep Modes with Wake$-$Up Button

Objective: Put the Arduino into Power$-$down sleep mode to conserve power and wake it up using a button interrupt.

Instructions:

Configure the Arduino to enter Power$-$down mode when idle. Attach a button to pin $3$ to wake the Arduino when pressed. In sleep mode, all unnecessary functions are disabled, and the Arduino only wakes up when the button interrupt is triggered.

Code Template:

#include

#include

$$

const int buttonPin $=3$;

$$

void setup$()\{$

$$ pinMode$($buttonPin$,$ INPUT$\_$PULLUP$)$;$//$ Set button as input with pull$-$up

$$ attachInterrupt$($digitalPinToInterrupt$($buttonPin$),$ wakeUp, FALLING$)$; $//$ Interrupt on button press

$$ Serial.begin$(9600)$;$//$ Optional: for monitoring in Serial Monitor

$\}$

$$

void loop$()\{$

$$ Serial.println$("$Going to sleep..."$)$;

$$ delay$(1000)$;

$$

$//$ Configure sleep mode

$$ set$\_$sleep$\_$mode$($SLEEP$\_$MODE$\_$PWR$\_$DOWN$)$;

$$ sleep$\_$enable$()$;

$$ sleep$\_$mode$()$;$//$ Put the Arduino to sleep

$$

$//$ The Arduino resumes here after wake$-$up

$$ Serial.println$("$Woke up$!")$;

$$ delay$(1000)$;$//$ Wait a moment before going back to sleep

$\}$

$$

void wakeUp$()\{$

$//$ This function just interrupts sleep mode; no code needed

$\}$

Questions and Analysis

Task $1$: Describe how CTC mode allows for precise timing control without using delay$().$ How does changing the prescaler or compare match value affect the blink interval?

Task $2$: How does Power$-$down mode save power compared to other sleep modes? Describe the function of the button interrupt in waking up the Arduino from sleep mode.