Timer overflow behavior in Embedded C - Mini Project: Build & Apply

Timer Overflow Behavior

📖 Scenario: You are working with a simple microcontroller timer that counts from 0 to 255 and then overflows back to 0. This timer is used to measure time intervals in milliseconds.

🎯 Goal: Build a small program that simulates the timer counting up, detects when it overflows, and counts how many times the overflow happens.

📋 What You'll Learn

Create a variable timer to hold the timer value starting at 0

Create a variable overflow_count to count how many times the timer overflows

Use a loop to increment the timer variable simulating timer ticks

Detect when the timer overflows from 255 back to 0 and increase overflow_count

Print the final overflow_count after simulating 300 timer ticks

💡 Why This Matters

🌍 Real World

Microcontrollers use timers to measure time intervals and generate delays. Understanding overflow helps avoid errors in timing calculations.

💼 Career

Embedded software engineers often work with hardware timers and must handle overflow behavior correctly to build reliable systems.

1

Create timer and overflow counter variables

Create an unsigned char variable called timer and set it to 0. Also create an unsigned int variable called overflow_count and set it to 0.

Embedded C

unsigned char timer = 0;
unsigned int overflow_count = 0;
// Your code here

Need a hint?

Use unsigned char for the timer because it counts from 0 to 255.

2

Set the number of timer ticks to simulate

Create an int variable called ticks and set it to 300 to represent the number of timer increments to simulate.

Embedded C

unsigned char timer = 0;
unsigned int overflow_count = 0;
int ticks = 300;
// Your code here

Need a hint?

This variable controls how many times the timer will increment in the simulation.

3

Simulate timer increments and detect overflow

Write a for loop using int i from 0 to less than ticks. Inside the loop, increment timer by 1. If timer becomes 0 after incrementing, increase overflow_count by 1.

Embedded C

unsigned char timer = 0;
unsigned int overflow_count = 0;
int ticks = 300;

// Your code here

Need a hint?

Remember that when timer reaches 255 and increments, it wraps to 0 because it is an unsigned char.

4

Print the overflow count

Write a printf statement to print the text "Overflow count: " followed by the value of overflow_count and a newline.

Embedded C

unsigned char timer = 0;
unsigned int overflow_count = 0;
int ticks = 300;

for (int i = 0; i < ticks; i++) {
    timer++;
    if (timer == 0) {
        overflow_count++;
    }
}

// Your code here

Need a hint?

The timer overflows once after 256 increments, so the overflow count should be 1 after 300 ticks.