Wake-up from sleep with interrupt in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to put the Arduino into sleep mode.

Arduino

void setup() {
  pinMode(2, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(2), wakeUp, [1]);
}

void loop() {
  sleep_enable();
  sleep_cpu();
  sleep_disable();
}

void wakeUp() {
  // This function will be called when interrupt occurs
}

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AFALLING

BRISING

CCHANGE

DLOW

Attempts:

3 left

💡 Hint

Common Mistakes

Using RISING instead of FALLING causes the interrupt not to trigger on button press.

Not using digitalPinToInterrupt() for the pin number.

The interrupt is set to trigger on the FALLING edge, which means when the button connected to pin 2 is pressed (goes from HIGH to LOW).

2fill in blank

medium

Complete the code to enable sleep mode using the correct sleep mode constant.

Arduino

#include <avr/sleep.h>

void setup() {
  set_sleep_mode([1]);
}

void loop() {
  sleep_enable();
  sleep_cpu();
  sleep_disable();
}

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ASLEEP_MODE_IDLE

BSLEEP_MODE_PWR_DOWN

CSLEEP_MODE_ADC

DSLEEP_MODE_STANDBY

Attempts:

3 left

💡 Hint

Common Mistakes

Using SLEEP_MODE_IDLE which does not save much power.

Forgetting to include .

SLEEP_MODE_PWR_DOWN is the deepest sleep mode that turns off most of the Arduino's functions to save power.

3fill in blank

hard

Fix the error in the interrupt service routine to correctly wake the Arduino from sleep.

Arduino

void wakeUp() {
  [1]();
}

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Asleep_cpu

Bsleep_enable

Csleep_disable

DattachInterrupt

Attempts:

3 left

💡 Hint

Common Mistakes

Calling sleep_enable() inside the ISR causes the Arduino to stay asleep.

Calling attachInterrupt() inside the ISR is incorrect.

The wakeUp function should disable sleep mode by calling sleep_disable() to resume normal operation.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps pin numbers to their sleep modes if the pin number is greater than 3.

Arduino

const int pins[] = {2, 3, 4, 5};
std::map<int, int> pinSleepModes = [1];

// Example: pinSleepModes = {4: SLEEP_MODE_PWR_DOWN, 5: SLEEP_MODE_IDLE}

// Fill the blanks below

for (int pin : pins) {
  if (pin [2] 3) {
    pinSleepModes[pin] = SLEEP_MODE_PWR_DOWN;
  }
}

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Astd::map<int, int>()

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect comparison operators like '<' or '=='.

Not initializing the map before using it.

We initialize an empty map with std::map() and check if pin is greater than 3 to add it to the map.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps pin names to their sleep modes only if the mode is SLEEP_MODE_PWR_DOWN.

Arduino

std::map<std::string, int> pinModes = {
  {"pin2", SLEEP_MODE_IDLE},
  {"pin3", SLEEP_MODE_PWR_DOWN},
  {"pin4", SLEEP_MODE_PWR_DOWN}
};

std::map<std::string, int> filteredModes = {
  [1]: [2] for (const auto& [[3], mode] : pinModes) if (mode == SLEEP_MODE_PWR_DOWN)
};

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Apin

Bmode

Ckey

Dfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names that don't match the loop unpacking.

Not filtering by the correct sleep mode.

We use 'key' as the variable for the pin name and 'mode' for the sleep mode. The comprehension maps key to mode for modes equal to SLEEP_MODE_PWR_DOWN.