SPI data transfer sequence in Embedded C - Mini Project: Build & Apply

SPI Data Transfer Sequence

📖 Scenario: You are working with a microcontroller that communicates with a sensor using SPI (Serial Peripheral Interface). You need to write a simple program that sends a byte of data to the sensor and receives a byte back.

🎯 Goal: Build a program that performs a basic SPI data transfer sequence: initialize data, set a transfer byte, perform the SPI transfer, and print the received byte.

📋 What You'll Learn

Create a variable to hold the data to send

Create a variable to hold the received data

Create a variable for the SPI status

Write a function call to perform SPI transfer

Print the received data

💡 Why This Matters

🌍 Real World

SPI is a common way microcontrollers talk to sensors, memory chips, and other devices quickly and reliably.

💼 Career

Embedded developers often write SPI communication code to interface hardware components in products like IoT devices, automotive systems, and consumer electronics.

1

DATA SETUP: Define SPI data variables

Create a uint8_t variable called data_to_send and set it to 0x3A. Also create a uint8_t variable called data_received and initialize it to 0.

Embedded C

#include 
#include 

int main() {

    // Create data_to_send and data_received variables
    // Your code here

    return 0;
}

Need a hint?

Use uint8_t type for 8-bit data variables and assign the exact values.

2

CONFIGURATION: Define SPI status variable

Add a uint8_t variable called spi_status and initialize it to 0 to hold the SPI transfer status.

Embedded C

#include 
#include 

int main() {

    uint8_t data_to_send = 0x3A;
    uint8_t data_received = 0;

    // Create spi_status variable
    // Your code here

    return 0;
}

Need a hint?

Define spi_status as uint8_t and set it to zero.

3

CORE LOGIC: Perform SPI data transfer

Call the function spi_transfer with data_to_send as input, assign the returned value to data_received, and set spi_status to 1 to indicate success.

Embedded C

#include 
#include 

uint8_t spi_transfer(uint8_t data) {
    // Simulate SPI transfer by returning data incremented by 1
    return data + 1;
}

int main() {

    uint8_t data_to_send = 0x3A;
    uint8_t data_received = 0;
    uint8_t spi_status = 0;

    // Perform SPI transfer and update spi_status
    // Your code here

    return 0;
}

Need a hint?

Assign the result of spi_transfer(data_to_send) to data_received and set spi_status to 1.

4

OUTPUT: Print the received SPI data

Write a printf statement to display the text "Received data: 0x%X\n" with data_received as the value.

Embedded C

#include 
#include 

uint8_t spi_transfer(uint8_t data) {
    // Simulate SPI transfer by returning data incremented by 1
    return data + 1;
}

int main() {

    uint8_t data_to_send = 0x3A;
    uint8_t data_received = 0;
    uint8_t spi_status = 0;

    data_received = spi_transfer(data_to_send);
    spi_status = 1;

    // Print the received data
    // Your code here

    return 0;
}

Need a hint?

Use printf with format specifier 0x%X to print the received byte in hexadecimal.