Why power management matters in Embedded C - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the microcontroller to sleep mode.

Embedded C

MCUCR = (1 << [1]);

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ASM1

BSE

CSM0

DSM2

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong bit like SE instead of SM1.

Confusing SM bits with SE bit.

The SM1 bit in MCUCR register selects the sleep mode.

2fill in blank

medium

Complete the code to enable sleep mode by setting the sleep enable bit.

Embedded C

MCUCR |= (1 << [1]);

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

ASM0

BSM1

CSE

DSM2

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the wrong bit like SM0 instead of SE.

Not using bitwise OR to set the bit.

The SE bit enables the sleep mode when set.

3fill in blank

hard

Fix the error in the code to correctly put the MCU to sleep.

Embedded C

sleep_cpu();
MCUCR &= ~(1 << [1]);

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

ASM1

BSM0

CSM2

DSE

Attempts:

3 left

💡 Hint

Common Mistakes

Clearing the wrong bit like SM0 instead of SE.

Not clearing the bit after waking up.

After waking up, the SE bit should be cleared to disable sleep mode.

4fill in blank

hard

Fill both blanks to create a dictionary of power modes and their descriptions.

Embedded C

const char* power_modes[] = {"Idle", "Power-down", "Power-save", "Standby"};
const char* descriptions[] = {"CPU stopped", "Most devices off", "Timer running", [1];

const char* mode = power_modes[2];
const char* desc = descriptions[[2]];

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A"Lowest power mode"

B"Timer running"

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong index for descriptions array.

Mixing descriptions for different power modes.

The description for "Standby" mode is "Lowest power mode" and index 2 corresponds to "Power-save" mode.

5fill in blank

hard

Fill all three blanks to complete the function that configures and enters sleep mode.

Embedded C

void enter_sleep_mode() {
    MCUCR = (1 << [1]); // Set sleep mode
    MCUCR |= (1 << [2]); // Enable sleep
    [3](); // Enter sleep
    MCUCR &= ~(1 << [2]); // Disable sleep after wakeup
}

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

ASM1

BSE

Csleep_cpu

DSM0

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong bits for sleep mode selection.

Forgetting to disable sleep after waking.

Not calling the correct function to enter sleep.

Set SM1 bit to select sleep mode, set SE bit to enable sleep, call sleep_cpu() to enter sleep, then clear SE after waking.