Wake-up sources configuration in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a wake-up source in embedded systems?

A wake-up source is a hardware or software event that brings the microcontroller out of a low-power or sleep mode to resume normal operation.

beginner

Name three common wake-up sources in microcontrollers.

Common wake-up sources include external interrupts (like a button press), timers (RTC alarms), and communication peripherals (UART, I2C activity).

intermediate

How do you typically configure an external interrupt as a wake-up source in embedded C?

You enable the interrupt line, configure its trigger condition (rising/falling edge), and enable the microcontroller's wake-up capability on that interrupt line.

beginner

Why is it important to configure wake-up sources correctly?

Correct configuration ensures the device wakes up only on intended events, saving power and avoiding unwanted wake-ups that drain battery.

intermediate

Show a simple embedded C code snippet to enable a timer as a wake-up source.

// Enable timer interrupt as wake-up source Timer_EnableInterrupt(); Power_EnableWakeupSource(TIMER_INTERRUPT); Power_EnterSleepMode();

Which of the following can be a wake-up source in embedded systems?

A External interrupt

B Random number generator

C Display refresh

D Internal temperature sensor reading

External interrupts are common wake-up sources because they signal an event from outside the microcontroller.

What is the main purpose of configuring wake-up sources?

A To save power by waking up only on specific events

B To increase CPU speed

C To disable interrupts

D To reset the microcontroller

Wake-up sources help the device save power by waking only when needed.

Which trigger condition is commonly used for an external interrupt wake-up?

A Constant high level

B Rising edge

C No trigger

D Timer overflow

Rising edge triggers when the signal changes from low to high, commonly used for interrupts.

What happens if no wake-up source is configured before entering sleep mode?

A The device speeds up

B The device wakes up immediately

C The device resets

D The device may never wake up automatically

Without a wake-up source, the device stays in sleep mode indefinitely.

Which function might you call to enable a wake-up source in embedded C?

A UART_Close()

B Timer_Disable()

C Power_EnableWakeupSource()

D GPIO_SetLow()

Power_EnableWakeupSource() is typically used to enable a specific wake-up source.

Explain what a wake-up source is and why it is important in embedded systems.

Think about how devices save battery by sleeping and waking only when needed.

Describe the steps to configure an external interrupt as a wake-up source in embedded C.

Consider how you prepare the microcontroller to listen for an event before sleeping.