Start and stop conditions in Embedded C - Mini Project: Build & Apply

Start and Stop Conditions in I2C Communication

📖 Scenario: You are working with a microcontroller that communicates with a sensor using the I2C protocol. To start communication, you need to send a start condition, and to end communication, you need to send a stop condition.This project will guide you through writing code to generate these start and stop conditions using embedded C.

🎯 Goal: Write embedded C code to generate the I2C start and stop conditions by manipulating the SDA and SCL lines.

📋 What You'll Learn

Create variables representing SDA and SCL lines as integers.

Create a function to generate the start condition by setting SDA low while SCL is high.

Create a function to generate the stop condition by setting SDA high while SCL is high.

Print the states of SDA and SCL after start and stop conditions.

💡 Why This Matters

🌍 Real World

Microcontrollers use start and stop conditions to control communication on the I2C bus, which connects sensors and other devices.

💼 Career

Embedded systems engineers must understand how to generate and detect start and stop conditions to implement reliable I2C communication.

1

Setup SDA and SCL line variables

Create two integer variables called SDA and SCL and set both to 1 to represent the idle state of the I2C bus.

Embedded C

int SDA = 1;
int SCL = 1;
// Your code here

Need a hint?

The I2C bus is idle when both SDA and SCL lines are high (1).

2

Create start condition function

Write a function called start_condition that sets SDA to 0 while SCL remains 1 to generate the I2C start condition.

Embedded C

int SDA = 1;
int SCL = 1;

void start_condition() {
    // Your code here
}

Need a hint?

Start condition means SDA goes low while SCL stays high.

3

Create stop condition function

Write a function called stop_condition that sets SDA to 1 while SCL remains 1 to generate the I2C stop condition.

Embedded C

int SDA = 1;
int SCL = 1;

void start_condition() {
    SDA = 0;
    SCL = 1;
}

void stop_condition() {
    // Your code here
}

Need a hint?

Stop condition means SDA goes high while SCL stays high.

4

Print SDA and SCL states after start and stop

Call start_condition() and then print the values of SDA and SCL. Then call stop_condition() and print the values of SDA and SCL again. Use printf with the format: "SDA: %d, SCL: %d\n".

Embedded C

int SDA = 1;
int SCL = 1;

void start_condition() {
    SDA = 0;
    SCL = 1;
}

void stop_condition() {
    SDA = 1;
    SCL = 1;
}

int main() {
    // Your code here
    return 0;
}

Need a hint?

Call the functions and print the line states to see the start and stop conditions.