Sleep modes overview in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a sleep mode in embedded systems?

A sleep mode is a low-power state where the microcontroller reduces its activity to save energy while keeping essential functions ready to wake up quickly.

beginner

Name two common sleep modes in microcontrollers.

Two common sleep modes are:<br>1. Idle mode - CPU stops but peripherals keep running.<br>2. Power-down mode - most of the system is off, only wake-up sources remain active.

intermediate

How does idle mode differ from power-down mode?

Idle mode stops the CPU but keeps peripherals running, allowing faster wake-up.<br>Power-down mode shuts down most of the system for maximum power saving but takes longer to wake up.

beginner

What is a wake-up source in sleep modes?

A wake-up source is an event or signal (like a timer or external interrupt) that brings the microcontroller out of sleep mode to active operation.

beginner

Why are sleep modes important in embedded programming?

Sleep modes help save battery life and reduce power consumption, which is crucial for devices running on limited power sources like batteries.

Which sleep mode stops the CPU but keeps peripherals running?

A Idle mode

B Power-down mode

C Deep sleep mode

D Hibernate mode

Idle mode stops the CPU but allows peripherals to continue working.

What is the main benefit of using power-down mode?

A Faster wake-up time

B Increases CPU speed

C Keeps all peripherals active

D Maximum power saving

Power-down mode saves the most power by shutting down most of the system.

Which of these can be a wake-up source?

A Timer interrupt

B CPU clock speed

C Power supply voltage

D Memory size

Timer interrupts can wake the microcontroller from sleep.

Why do embedded systems use sleep modes?

A To increase processing speed

B To save power and extend battery life

C To improve graphics performance

D To increase memory capacity

Sleep modes reduce power consumption, saving battery life.

What happens during idle mode?

A Only peripherals stop

B CPU and peripherals stop

C Only CPU stops, peripherals run

D System resets

In idle mode, the CPU stops but peripherals keep running.

Explain the difference between idle mode and power-down mode in embedded systems.

Think about what stops and what keeps running in each mode.

Describe why sleep modes are important for battery-powered embedded devices.

Consider how power saving affects device usability.