Why SPI is used in Embedded C - See It in Action

Why SPI is used

📖 Scenario: Imagine you have a small robot that needs to talk to many sensors and devices quickly and clearly. To do this, it uses a special way to send messages called SPI.

🎯 Goal: You will create a simple program that shows why SPI (Serial Peripheral Interface) is used to connect devices. You will set up data, configure a speed limit, send data using SPI, and then show the result.

📋 What You'll Learn

Create a variable called data_to_send with the value 0x3F

Create a variable called spi_speed and set it to 1000000 (1 MHz)

Write a function called spi_transfer that takes data and speed and returns the data sent

Print the result of sending data_to_send using spi_speed

💡 Why This Matters

🌍 Real World

SPI is used in many devices like sensors, displays, and memory chips to send data quickly and reliably.

💼 Career

Understanding SPI helps in embedded systems programming, hardware interfacing, and working with microcontrollers.

1

DATA SETUP: Create the data to send

Create a variable called data_to_send and set it to 0x3F.

Embedded C

# Create a variable called data_to_send and set it to 0x3F
# Your code here

Need a hint?

Use unsigned char to store one byte of data.

2

CONFIGURATION: Set SPI speed

Create a variable called spi_speed and set it to 1000000 (1 MHz).

Embedded C

unsigned char data_to_send = 0x3F;
// Create a variable called spi_speed and set it to 1000000
# Your code here

Need a hint?

Use unsigned int for the speed variable.

3

CORE LOGIC: Write SPI transfer function

Write a function called spi_transfer that takes unsigned char data and unsigned int speed and returns the data sent.

Embedded C

unsigned char data_to_send = 0x3F;
unsigned int spi_speed = 1000000;

// Write spi_transfer function below
# Your code here

Need a hint?

The function should return the data it receives.

4

OUTPUT: Send data and print result

Call spi_transfer with data_to_send and spi_speed, store the result in sent_data, and print it using printf.

Embedded C

unsigned char data_to_send = 0x3F;
unsigned int spi_speed = 1000000;

unsigned char spi_transfer(unsigned char data, unsigned int speed) {
    // In real SPI, data is sent at speed. Here we just return data to simulate.
    return data;
}

// Call spi_transfer and print the sent data
# Your code here

Need a hint?

Use printf("Sent data: 0x%X\n", sent_data); to print the result in hexadecimal.