I2C vs SPI decision matrix in Embedded C - Hands-On Comparison

I2C vs SPI Decision Matrix

📖 Scenario: You are working on a small embedded system project. You need to decide whether to use I2C or SPI communication protocol to connect sensors and devices.To help with this, you will create a simple decision matrix in C that stores key features of I2C and SPI and then selects the best protocol based on user requirements.

🎯 Goal: Build a C program that stores the features of I2C and SPI in a structured way, sets a requirement threshold, compares the protocols against the threshold, and prints which protocol is better for the given requirements.

📋 What You'll Learn

Create a struct to hold protocol features

Create two variables for I2C and SPI with exact feature values

Create a threshold variable for minimum required speed

Write a function or logic to compare protocols based on speed

Print the name of the protocol that meets or exceeds the threshold

💡 Why This Matters

🌍 Real World

Embedded systems often need to choose between I2C and SPI for device communication based on speed and wiring complexity.

💼 Career

Understanding how to compare hardware protocols and implement decision logic is useful for embedded software engineers and firmware developers.

1

Create protocol feature structures

Create a struct Protocol with const char* name and int speed_kbps. Then create two variables: i2c with "I2C" and speed 400, and spi with "SPI" and speed 10000.

Embedded C

# Define struct Protocol and create variables i2c and spi
# Your code here

Need a hint?

Use a struct with two fields: name and speed_kbps. Initialize i2c and spi with the exact values.

2

Set minimum speed requirement

Create an int variable called min_speed and set it to 1000 to represent the minimum required speed in kbps.

Embedded C

struct Protocol {
    const char* name;
    int speed_kbps;
};

struct Protocol i2c = {"I2C", 400};
struct Protocol spi = {"SPI", 10000};

// Create min_speed variable
# Your code here

Need a hint?

Just create an integer variable named min_speed and assign 1000.

3

Compare protocols based on speed

Write an if statement to check if i2c.speed_kbps is greater than or equal to min_speed. If yes, set a const char* variable best_protocol to i2c.name. Otherwise, set best_protocol to spi.name.

Embedded C

struct Protocol {
    const char* name;
    int speed_kbps;
};

struct Protocol i2c = {"I2C", 400};
struct Protocol spi = {"SPI", 10000};

int min_speed = 1000;

// Compare speeds and assign best_protocol
# Your code here

Need a hint?

Use an if-else to compare speeds and assign best_protocol accordingly.

4

Print the best protocol

Write a printf statement to print "Best protocol: %s\n" with the variable best_protocol.

Embedded C

struct Protocol {
    const char* name;
    int speed_kbps;
};

struct Protocol i2c = {"I2C", 400};
struct Protocol spi = {"SPI", 10000};

int min_speed = 1000;

const char* best_protocol;

if (i2c.speed_kbps >= min_speed) {
    best_protocol = i2c.name;
} else {
    best_protocol = spi.name;
}

// Print the best protocol
# Your code here

Need a hint?

Use printf to show the best_protocol string with a newline.