Standby mode behavior in Embedded C - Mini Project: Build & Apply

Standby Mode Behavior

📖 Scenario: You are working on a simple embedded system that needs to save power by entering standby mode when idle. In standby mode, the system stops most activities but can wake up on an external event.

🎯 Goal: Build a small program that simulates entering standby mode and waking up on an external event using flags and simple functions.

📋 What You'll Learn

Create a variable to represent the system state

Create a variable to represent an external wake-up event

Write a function to enter standby mode

Write a function to simulate an external event waking the system

Print the system state before and after standby mode

💡 Why This Matters

🌍 Real World

Embedded systems often need to save power by entering standby mode and waking up on events like button presses or sensor signals.

💼 Career

Understanding standby mode behavior is important for embedded software engineers working on low-power devices such as wearables, IoT sensors, and mobile electronics.

1

Create system state variable

Create an integer variable called system_state and set it to 0 to represent the system being active.

Embedded C

# Create an integer variable called system_state and set it to 0
# Your code here

Need a hint?

Use int system_state = 0; to create the variable.

2

Create external event flag

Create an integer variable called wake_event and set it to 0 to represent no external event.

Embedded C

int system_state = 0; // 0 means active
// Create an integer variable called wake_event and set it to 0
# Your code here

Need a hint?

Use int wake_event = 0; to create the variable.

3

Write standby and wake functions

Write a function called enter_standby() that sets system_state to 1 (standby). Write another function called wake_up() that sets wake_event to 1 and system_state back to 0 (active).

Embedded C

int system_state = 0; // 0 means active
int wake_event = 0; // 0 means no event
// Write enter_standby() and wake_up() functions
# Your code here

Need a hint?

Define two functions: enter_standby() and wake_up() that change the variables as described.

4

Simulate standby and wake-up with output

Write a main() function that prints system_state, calls enter_standby(), prints system_state again, calls wake_up(), and finally prints system_state and wake_event.

Embedded C

int system_state = 0; // 0 means active
int wake_event = 0; // 0 means no event

void enter_standby() {
    system_state = 1; // 1 means standby
}

void wake_up() {
    wake_event = 1; // event occurred
    system_state = 0; // back to active
}

// Write main() to print states and call functions
# Your code here

Need a hint?

Use printf to show the values and call the functions in order.