Deep sleep mode in ARM Architecture - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enter deep sleep mode on an ARM processor.

ARM Architecture

SCB->SCR |= [1];

Drag options to blanks, or click blank then click option'

ASCB_SCR_SLEEP_Msk

BSCB_SCR_SLEEPONEXIT_Msk

CSCB_SCR_SEVONPEND_Msk

DSCB_SCR_SLEEPDEEP_Msk

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong SCR bit like SLEEPONEXIT which controls sleep on ISR exit.

Confusing deep sleep with normal sleep bits.

The SCB_SCR_SLEEPDEEP_Msk bit in the System Control Block's SCR register enables deep sleep mode on ARM processors.

2fill in blank

medium

Complete the code to execute the WFI (Wait For Interrupt) instruction to enter sleep.

ARM Architecture

__[1]();

Drag options to blanks, or click blank then click option'

AWFI

BWFE

CSEV

DNOP

Attempts:

3 left

💡 Hint

Common Mistakes

Using WFE (Wait For Event) instead of WFI.

Using NOP which does nothing.

The WFI instruction tells the processor to wait for an interrupt, entering sleep mode until an interrupt occurs.

3fill in blank

hard

Fix the error in the code that attempts to clear the deep sleep bit.

ARM Architecture

SCB->SCR &= ~[1];

Drag options to blanks, or click blank then click option'

ASCB_SCR_SLEEPONEXIT_Msk

BSCB_SCR_SLEEPDEEP_Msk

CSCB_SCR_SEVONPEND_Msk

DSCB_SCR_SLEEP_Msk

Attempts:

3 left

💡 Hint

Common Mistakes

Clearing the wrong bit mask.

Forgetting to use the bitwise NOT operator.

To clear the deep sleep bit, you must use the SCB_SCR_SLEEPDEEP_Msk mask with bitwise NOT and AND operations.

4fill in blank

hard

Fill both blanks to create a dictionary that maps power modes to their descriptions.

ARM Architecture

power_modes = {"sleep": [1], "deep_sleep": [2]

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A"Low power mode"

B"Processor halts until interrupt"

C"Processor halts until reset"

D"Lowest power consumption state"

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing descriptions of sleep and deep sleep modes.

Using incorrect descriptions that don't match the mode.

"sleep" mode means the processor halts until an interrupt, while "deep_sleep" is the lowest power consumption state.

5fill in blank

hard

Fill all three blanks to complete the code that sets the processor to deep sleep, executes WFI, and then clears the deep sleep bit.

ARM Architecture

SCB->SCR |= [1];
__[2]();
SCB->SCR &= ~[3];

Drag options to blanks, or click blank then click option'

ASCB_SCR_SLEEPDEEP_Msk

BWFI

DWFE

Attempts:

3 left

💡 Hint

Common Mistakes

Using WFE instead of WFI.

Not clearing the deep sleep bit after waking.

First, set the deep sleep bit with SCB_SCR_SLEEPDEEP_Msk, then execute the WFI instruction to enter sleep, and finally clear the deep sleep bit.