Why serial communication is needed in Embedded C - See It in Action

Why Serial Communication is Needed

📖 Scenario: You are working on a small embedded system project where two devices need to exchange data. One device is a microcontroller, and the other is a sensor module. To make them talk to each other, you need to use serial communication.

🎯 Goal: Understand why serial communication is needed by creating a simple program that sets up data to send and receive using serial communication concepts.

📋 What You'll Learn

Create a variable to hold data to send

Create a variable to hold received data

Set a baud rate configuration variable

Simulate sending data using a function

Print the received data

💡 Why This Matters

🌍 Real World

Serial communication is used in embedded systems to connect sensors, displays, and other modules with microcontrollers using minimal wiring.

💼 Career

Understanding serial communication is essential for embedded engineers to design and debug hardware interfaces and communication protocols.

1

DATA SETUP: Create data variables

Create a char array called dataToSend with the value "Hello" and a char variable called receivedData initialized to '\0'.

Embedded C

# Create dataToSend and receivedData variables
// Your code here

Hint

Use a character array for the data to send and a char variable for received data.

2

CONFIGURATION: Set baud rate

Create an int variable called baudRate and set it to 9600.

Embedded C

char dataToSend[] = "Hello";
char receivedData = '\0';
// Set baudRate to 9600
// Your code here

Hint

Baud rate is the speed of serial communication. Use an integer variable.

3

CORE LOGIC: Simulate sending and receiving data

Write a function called sendData that takes a char* parameter called data and sets receivedData to the first character of data. Then call sendData with dataToSend.

Embedded C

char dataToSend[] = "Hello";
char receivedData = '\0';
int baudRate = 9600;
// Write sendData function and call it
// Your code here

Hint

Simulate sending by copying the first character from dataToSend to receivedData.

4

OUTPUT: Print the received data

Write a printf statement to print receivedData as a character.

Embedded C

#include 

char dataToSend[] = "Hello";
char receivedData = '\0';
int baudRate = 9600;

void sendData(char* data) {
    receivedData = data[0];
}

int main() {
    sendData(dataToSend);
    // Print receivedData
    // Your code here
    return 0;
}

Hint

Use printf("Received data: %c\n", receivedData); to show the received character.

Practice

1. Why is serial communication commonly used in embedded systems?

easy

A. Because it only works with wireless devices

B. Because it sends data all at once using many wires

C. Because it requires no physical connection between devices

D. Because it uses fewer wires to send data bit by bit

Solution

1. Step 1: Understand serial communication basics

   Serial communication sends data one bit at a time, which means it uses fewer wires compared to parallel communication.

2. Step 2: Relate to embedded systems needs

   Embedded systems often have limited pins and need simple wiring, so sending data bit by bit with fewer wires is ideal.

3. Final Answer:

   Because it uses fewer wires to send data bit by bit -> Option D

4. Quick Check:

   Serial communication = fewer wires [OK]

Hint: Serial means one bit at a time, so fewer wires needed [OK]

Common Mistakes:

• Thinking serial sends all data at once
• Confusing serial with wireless communication
• Assuming no wires are needed

2. Which of the following is the correct way to initialize UART serial communication in embedded C?

easy

A. uart_start(9600);

B. Serial.begin(9600);

C. UART_Init(9600);

D. init_uart(9600);

Solution

1. Step 1: Identify standard UART initialization function

   In embedded C, UART is commonly initialized with a function like UART_Init that takes baud rate as argument.

2. Step 2: Check syntax correctness

   UART_Init(9600); is a typical correct syntax, while others are either Arduino style or made-up functions.

3. Final Answer:

   UART_Init(9600); -> Option C

4. Quick Check:

   UART_Init is standard init function [OK]

Hint: Look for standard C style function names for UART [OK]

Common Mistakes:

• Using Arduino style Serial.begin in embedded C
• Using undefined function names
• Missing baud rate parameter

3. What will be the output of this embedded C code snippet if serial communication sends the character 'A'?

char received = UART_Read();
printf("Received: %c", received);

medium

A. Received: A

B. Received: 65

C. Received: \0

D. Compilation error

Solution

1. Step 1: Understand UART_Read() behavior

   UART_Read() reads one byte from serial and returns it as a char, so if 'A' is sent, it returns 'A'.

2. Step 2: Analyze printf output

   Using %c in printf prints the character itself, so it will print 'Received: A'.

3. Final Answer:

   Received: A -> Option A

4. Quick Check:

   UART_Read returns char, %c prints char [OK]

Hint: %c prints char, UART_Read returns char [OK]

Common Mistakes:

• Confusing %c with %d in printf
• Expecting numeric ASCII code output
• Assuming UART_Read returns integer

4. Identify the error in this code snippet for serial communication setup:

void setup() {
  UART_Init();
  UART_SetBaudRate(9600);
}

medium

A. UART_Init() needs baud rate parameter

B. UART_SetBaudRate() should be called before UART_Init()

C. UART_Init() and UART_SetBaudRate() cannot be used together

D. No error, code is correct

Solution

1. Step 1: Check UART_Init() function usage

   Typically, UART_Init() requires the baud rate as a parameter to configure communication speed.

2. Step 2: Analyze function calls order and necessity

   Calling UART_SetBaudRate() separately is redundant if UART_Init() already sets baud rate; missing parameter causes error.

3. Final Answer:

   UART_Init() needs baud rate parameter -> Option A

4. Quick Check:

   UART_Init(baud) required [OK]

Hint: UART_Init usually needs baud rate parameter [OK]

Common Mistakes:

• Calling UART_Init without parameters
• Assuming baud rate can be set after init
• Thinking both functions are always needed

5. You want to connect a sensor with only 3 pins to a microcontroller over a long distance. Why is serial communication preferred over parallel communication in this case?

hard

A. Because parallel communication is faster and better for long distances

B. Because serial communication uses fewer wires, reducing complexity and noise over long cables

C. Because serial communication requires more wires, which improves reliability

D. Because parallel communication can only send data bit by bit

Solution

1. Step 1: Consider wiring complexity for long distance

   Long cables are prone to noise; fewer wires mean less interference and simpler connections.

2. Step 2: Compare serial and parallel communication

   Serial sends data bit by bit using fewer wires, making it better for long distances and limited pins.

3. Step 3: Eliminate incorrect options

   Parallel communication uses many wires and is not ideal for long distances; serial communication does not require more wires.

4. Final Answer:

   Because serial communication uses fewer wires, reducing complexity and noise over long cables -> Option B

5. Quick Check:

   Fewer wires = better for long distance [OK]

Hint: Fewer wires means less noise and simpler long-distance wiring [OK]

Common Mistakes:

• Thinking parallel is better for long distances
• Assuming serial needs more wires
• Confusing bit by bit sending with parallel