Wake-up from sleep with interrupt in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of using interrupts to wake up an Arduino from sleep mode?

Interrupts allow the Arduino to wake up immediately when a specific event occurs, saving power by sleeping until needed.

beginner

Which Arduino function is used to put the microcontroller into sleep mode?

The sleep_mode() function from the avr/sleep.h library is used to put the Arduino into sleep mode.

intermediate

How do you attach an interrupt to a pin to wake the Arduino from sleep?

Use attachInterrupt(digitalPinToInterrupt(pin), ISR, mode) where ISR is the interrupt service routine and mode defines the trigger condition (e.g., RISING).

intermediate

What must you do inside the Interrupt Service Routine (ISR) to wake the Arduino from sleep?

The ISR should be short and can set a flag or simply return; the interrupt itself wakes the Arduino from sleep automatically.

advanced

Why is it important to disable ADC and other peripherals before sleeping?

Disabling ADC and unused peripherals reduces power consumption, making sleep mode more effective.

Which library is commonly used to control sleep modes on Arduino?

A Wire.h

B avr/sleep.h

C SPI.h

D EEPROM.h

The avr/sleep.h library provides functions to manage sleep modes on Arduino.

What does attachInterrupt(digitalPinToInterrupt(pin), ISR, RISING) do?

A Sets an interrupt on the pin triggered when the signal rises

B Puts the Arduino to sleep

C Disables the interrupt on the pin

D Reads the digital value of the pin

It attaches an interrupt to the specified pin that triggers the ISR when the signal changes from LOW to HIGH.

What happens when an interrupt occurs while Arduino is sleeping?

A Arduino shuts down

B Arduino stays asleep

C Arduino resets

D Arduino wakes up and runs the ISR

An interrupt wakes the Arduino from sleep and executes the interrupt service routine.

Which of these is NOT a valid interrupt trigger mode?

A STABLE

B FALLING

C RISING

D CHANGE

STABLE is not a valid interrupt trigger mode; valid modes include RISING, FALLING, and CHANGE.

Why should the ISR be kept short when waking from sleep?

A To disable interrupts

B To use more memory

C To quickly return control and avoid delays

D To put Arduino back to sleep

Short ISRs ensure the Arduino resumes normal operation quickly without blocking other processes.

Explain how to set up an Arduino to wake up from sleep using an external interrupt.

Think about the steps from preparing sleep to waking up with a button press.

Describe why using interrupts to wake from sleep is better for power saving than polling.

Compare continuous checking vs waiting quietly.