SPI master-slave architecture in Embedded C - Mini Project: Build & Apply

SPI Master-Slave Architecture

📖 Scenario: You are working on a simple embedded system where a master device communicates with a slave device using SPI (Serial Peripheral Interface). The master sends commands and data to the slave, and the slave responds accordingly.This project will guide you through setting up basic SPI communication in C, simulating the master and slave roles.

🎯 Goal: Build a simple SPI master-slave communication program in C where the master sends a byte to the slave, and the slave receives and stores it.

📋 What You'll Learn

Create a variable to represent the data byte to send from the master

Create a variable to represent the received data byte in the slave

Simulate the SPI transfer function that sends data from master to slave

Print the received data byte in the slave to verify communication

💡 Why This Matters

🌍 Real World

SPI is a common way microcontrollers and sensors communicate in devices like smart home gadgets, wearables, and industrial machines.

💼 Career

Understanding SPI communication is essential for embedded systems engineers working on hardware interfacing and device drivers.

1

Create SPI data variables

Create a variable called master_data and set it to 0x3A. Also create a variable called slave_data and initialize it to 0x00.

Embedded C

# Create variables master_data and slave_data
# Your code here

Need a hint?

Use unsigned char type for 8-bit data bytes.

2

Create SPI transfer function prototype

Create a function prototype called spi_transfer that takes an unsigned char parameter called data_out and returns an unsigned char.

Embedded C

unsigned char master_data = 0x3A;
unsigned char slave_data = 0x00;

// Declare spi_transfer function prototype
# Your code here

Need a hint?

Function prototype declares the function signature without the body.

3

Implement SPI transfer function

Implement the spi_transfer function so that it assigns the input data_out to the global variable slave_data and returns slave_data.

Embedded C

unsigned char master_data = 0x3A;
unsigned char slave_data = 0x00;

unsigned char spi_transfer(unsigned char data_out) {
    // Your code here
}

Need a hint?

Assign the input to slave_data and return it.

4

Send data and print received value

Call the spi_transfer function with master_data and store the result in a variable called received. Then print the value of received in hexadecimal format using printf.

Embedded C

unsigned char master_data = 0x3A;
unsigned char slave_data = 0x00;

unsigned char spi_transfer(unsigned char data_out) {
    slave_data = data_out;
    return slave_data;
}

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

Need a hint?

Use printf("Received data: 0x%02X\n", received); to print the hexadecimal value.