State machine design for Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the initial state of the state machine.

Arduino

enum State { IDLE, RUNNING, ERROR };
State currentState = [1];

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ARUNNING

BIDLE

CERROR

DSTART

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a state that is not defined in the enum.

Using a string instead of the enum value.

The initial state is usually set to IDLE to indicate the system is waiting to start.

2fill in blank

medium

Complete the code to check if the current state is RUNNING.

Arduino

if (currentState == [1]) {
  // do something
}

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ARUNNING

BIDLE

CERROR

DSTART

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string like "RUNNING" instead of the enum value.

Comparing to a state not defined in the enum.

To check if the state machine is in the RUNNING state, compare currentState to RUNNING.

3fill in blank

hard

Fix the error in the switch statement to handle the ERROR state.

Arduino

switch (currentState) {
  case IDLE:
    // do idle tasks
    break;
  case RUNNING:
    // do running tasks
    break;
  case [1]:
    // handle error
    break;
}

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APAUSE

BSTOP

CSTART

DERROR

Attempts:

3 left

💡 Hint

Common Mistakes

Using a state name not defined in the enum.

Using a string instead of the enum value.

The switch statement must use the enum value ERROR to handle the error state correctly.

4fill in blank

hard

Fill both blanks to update the state to RUNNING when a button is pressed.

Arduino

if (digitalRead(buttonPin) == [1]) {
  currentState = [2];
}

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AHIGH

BLOW

CRUNNING

DIDLE

Attempts:

3 left

💡 Hint

Common Mistakes

Using LOW instead of HIGH for button press.

Setting state to IDLE instead of RUNNING.

When the button is pressed (reads HIGH), the state changes to RUNNING.

5fill in blank

hard

Fill all three blanks to create a state machine loop that handles IDLE and RUNNING states.

Arduino

void loop() {
  switch (currentState) {
    case [1]:
      // wait for start
      if (digitalRead(startPin) == HIGH) {
        currentState = [2];
      }
      break;
    case [3]:
      // running tasks
      // ...
      break;
  }
}

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

AIDLE

BRUNNING

CERROR

DSTART

Attempts:

3 left

💡 Hint

Common Mistakes

Using ERROR state instead of RUNNING for running tasks.

Mixing up the order of states.

The loop waits in IDLE state, switches to RUNNING when start is pressed, and handles running tasks in RUNNING state.