Low-power design patterns in Embedded C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enter low-power sleep mode.

Embedded C

void enter_sleep_mode() {
    __[1]();
}

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AWFI

BNOP

CSVC

DWFE

Attempts:

3 left

💡 Hint

Common Mistakes

Using NOP does not put the CPU to sleep.

Using SVC triggers a supervisor call, not sleep.

WFE waits for an event, but WFI is more common for sleep.

The WFI instruction puts the processor into sleep mode until an interrupt occurs, saving power.

2fill in blank

medium

Complete the code to disable the peripheral clock to save power.

Embedded C

void disable_peripheral_clock() {
    RCC->APB1ENR &= ~[1];
}

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ARCC_APB1ENR_TIM2EN

BRCC_APB1ENR_I2C1EN

CRCC_APB1ENR_USART1EN

DRCC_APB1ENR_SPI2EN

Attempts:

3 left

💡 Hint

Common Mistakes

Disabling the wrong peripheral clock.

Using the wrong register bit mask.

Disabling the I2C1 peripheral clock saves power when the I2C1 peripheral is not used.

3fill in blank

hard

Fix the error in the code to correctly configure the microcontroller to enter STOP mode.

Embedded C

void enter_stop_mode() {
    PWR->CR |= PWR_CR_LPDS;
    PWR->CR &= ~[1];
    SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
    __WFI();
}

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APWR_CR_ULP

BPWR_CR_CWUF

CPWR_CR_LPSDSR

DPWR_CR_PDDS

Attempts:

3 left

💡 Hint

Common Mistakes

Clearing the wrong bit causes the MCU to enter STANDBY mode.

Not setting SLEEPDEEP bit prevents deep sleep.

Clearing PWR_CR_PDDS bit configures the device to enter STOP mode instead of STANDBY mode.

4fill in blank

hard

Complete the code to create a dictionary comprehension that maps sensor names to their power states only if the sensor is active.

Embedded C

sensor_power = {name: state for name, state in sensors.items() if state [1] 1}

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B==

C!=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Adding an operator after state in the value expression.

Using != or > instead of == in the condition.

The comprehension includes sensors where state == 1, meaning active sensors. No operator is needed after state in the value expression.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps device IDs (uppercase) to their power levels only if the level is above zero.

Embedded C

power_levels = [1]: [2] for id, level in devices.items() if level [3] 0}

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Aid.upper()

Blevel

C>

Did.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using id.lower() instead of uppercase.

Using < or == instead of >.

Swapping keys and values in the comprehension.

The comprehension maps uppercase device IDs to their power levels only if the level is greater than zero.