Microcontrollers with UART

What is UART?

UART (Universal Asynchronous Receiver-Transmitter) is a widely used communication protocol in embedded systems for serial data transmission. It enables full-duplex communication between devices by converting parallel data into serial format and vice versa.

Key Features of UART

• Asynchronous Communication: No need for a shared clock between devices.
• Two-Wire Interface: Uses TX (transmit) and RX (receive) lines for communication.
• Configurable Baud Rate: Supports a wide range of speeds (e.g., 9600, 115200 bps).
• Start and Stop Bits: Synchronizes data transmission between devices.
• Error Detection: Includes parity bit and frame error detection.

Microcontrollers with Built-in UART

Most modern microcontrollers include built-in UART modules for easy serial communication. Examples include:

• Arduino: UART is available on pins 0 (RX) and 1 (TX).
• ESP32/ESP8266: Provides multiple UART peripherals for flexible serial communication.
• STM32 Series: Features USART (UART with synchronous mode) for advanced functionality.
• Raspberry Pi Pico: Offers two UART peripherals for serial communication.
• Microchip PIC and AVR: Integrated UART modules for embedded projects.

How to Set Up UART Communication

To use UART, connect the TX pin of one device to the RX pin of another and vice versa. Below are the basic steps:

Basic Steps:

1. Connect the TX pin of the microcontroller to the RX pin of the peripheral device.
2. Connect the RX pin of the microcontroller to the TX pin of the peripheral device.
3. Configure the baud rate, data bits, parity, and stop bits in the microcontroller's code.
4. Initialize the UART module in your code and test the communication.

Example Code: UART Communication

Using Arduino for UART Communication

// Example UART communication using Arduino
void setup() {
    Serial.begin(9600); // Initialize UART at 9600 baud
    Serial.println("UART Initialized");
}

void loop() {
    if (Serial.available()) {
        char received = Serial.read(); // Read received data
        Serial.print("Received: ");
        Serial.println(received); // Echo received data
    }
    Serial.println("Sending Data...");
    Serial.println("Hello, UART!");
    delay(1000);
}
            

Using STM32 HAL for UART

// Example UART communication using STM32 HAL
#include "main.h"

UART_HandleTypeDef huart2;

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {
    if (huart->Instance == USART2) {
        char receivedData;
        HAL_UART_Receive(&huart2, (uint8_t*)&receivedData, 1, HAL_MAX_DELAY);
        HAL_UART_Transmit(&huart2, (uint8_t*)&receivedData, 1, HAL_MAX_DELAY); // Echo data
    }
}

int main(void) {
    HAL_Init();
    SystemClock_Config();
    MX_USART2_UART_Init();
    HAL_UART_Transmit(&huart2, (uint8_t*)"UART Initialized\r\n", 18, HAL_MAX_DELAY);
    while (1) {
        // Loop forever
    }
}
            

Troubleshooting UART

Common issues and solutions:

• Garbled Data: Ensure both devices use the same baud rate and settings.
• No Communication: Verify TX and RX connections and ensure devices are powered.
• Buffer Overflow: Increase buffer size or use hardware flow control if available.

Example Projects with UART

Project 1: Serial Data Logger

Log sensor data from a microcontroller to a PC using UART communication.

Project 2: Wireless UART Bridge

Use two microcontrollers with UART to create a wireless data bridge using modules like HC-12 or Bluetooth.

Further Reading

To learn more about UART, explore these resources:

• Mastering UART Communication - A detailed guide for beginners and experts.
• UART Projects and Applications - Practical tutorials for real-world use.

Conclusion

UART is a fundamental protocol for serial communication in embedded systems. Its simplicity and versatility make it an essential tool for connecting microcontrollers to various devices.