Input capture mode in Embedded C - Mini Project: Build & Apply

Input Capture Mode in Embedded C

📖 Scenario: You are working with a microcontroller that needs to measure the time between two events using input capture mode. This is common in real-world applications like measuring the speed of a rotating wheel or the duration of a pulse signal.

🎯 Goal: Build a simple embedded C program that sets up input capture mode on a timer, captures the input event time, and stores the captured value.

📋 What You'll Learn

Create a variable to store the captured timer value

Configure the timer input capture mode

Write an interrupt service routine to read the captured value

Print the captured value to the console (simulate with a print statement)

💡 Why This Matters

🌍 Real World

Input capture mode is used in embedded systems to measure time intervals precisely, such as speed sensors, pulse width measurement, and frequency counting.

💼 Career

Understanding input capture mode is important for embedded software engineers working with microcontrollers in automotive, robotics, and industrial automation.

1

Create a variable to store the captured timer value

Create an unsigned int variable called captured_value and initialize it to 0.

Embedded C

# Create an unsigned int variable called captured_value and set it to 0
// Your code here

Need a hint?

Use the syntax unsigned int captured_value = 0; to declare and initialize.

2

Configure the timer input capture mode

Write a function called setup_input_capture() that configures the timer for input capture mode. Inside the function, set a hypothetical register TIMER_ICR to 1 to enable input capture.

Embedded C

unsigned int captured_value = 0;

// Write a function setup_input_capture() to enable input capture mode
// Your code here

Need a hint?

Define a function with void setup_input_capture() and inside set TIMER_ICR = 1;.

3

Write an interrupt service routine to read the captured value

Write an interrupt service routine function called input_capture_ISR(). Inside it, assign the value of a hypothetical register TIMER_ICV to the variable captured_value.

Embedded C

unsigned int captured_value = 0;

void setup_input_capture() {
    TIMER_ICR = 1; // Enable input capture mode
}

// Write an ISR function input_capture_ISR() to read TIMER_ICV into captured_value
// Your code here

Need a hint?

Define void input_capture_ISR() and inside assign captured_value = TIMER_ICV;.

4

Print the captured value

Write a main() function that calls setup_input_capture(), simulates an input capture event by setting TIMER_ICV = 1234;, calls input_capture_ISR(), and then prints the captured_value using printf.

Embedded C

unsigned int captured_value = 0;

void setup_input_capture() {
    TIMER_ICR = 1; // Enable input capture mode
}

void input_capture_ISR() {
    captured_value = TIMER_ICV; // Read captured timer value
}

// Write main() to call setup_input_capture(), simulate input capture, call ISR, and print captured_value
// Your code here

Need a hint?

Remember to include stdio.h and use printf to display the captured value.