How to Implement UART Communication in Your Firmware

Understand UART Communication Basics

• UART (Universal Asynchronous Receiver-Transmitter) is a hardware communication protocol using serial data exchange.

 

• In UART, data is sent byte-by-byte, and it does not require a clock signal, making it asynchronous.

Identify Your UART Hardware Specifications

• Check the datasheet of your microcontroller to determine the number of UART interfaces available.

 

• Identify the GPIO pins assigned for UART communication—TX (Transmit) and RX (Receive).

Configure UART Parameters

• Select the baud rate: Common choices are 9600, 19200, 38400, etc., but it should match the communicating device.

 

• Set frame format: Typically, 8 data bits, no parity, and 1 stop bit (8N1) is standard, but this may vary based on your application.

Initialize UART in Firmware

• Include the appropriate header files in your firmware project for accessing UART registers and functions.

 

• Initialize UART-related GPIO pins for alternate functions.

 

• Set up the UART peripheral by configuring control registers with your selected parameters.

<li>Configure the baud rate register.</li>

<li>Enable UART by setting the appropriate bits in the control register.</li>

UART Initialization Code Example in C

#include "stm32f4xx_hal.h"

void UART_Init(void) {
    // Configure UART parameters
    UART_HandleTypeDef huart;
    huart.Instance = USART2;  // Example for STM32 microcontroller
    huart.Init.BaudRate = 9600;
    huart.Init.WordLength = UART_WORDLENGTH_8B;
    huart.Init.StopBits = UART_STOPBITS_1;
    huart.Init.Parity = UART_PARITY_NONE;
    huart.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart.Init.Mode = UART_MODE_TX_RX;
    
    // Initialize the UART peripheral
    if (HAL_UART_Init(&huart) != HAL_OK) {
        // Initialization error
        while (1);
    }
}

Implement Data Transmission

• Implement a function for transmitting data over UART by writing bytes to the transmit data register.

 

• Use polling, interrupt, or DMA methods based on the application needs for data handling.

Example of Sending Data Over UART

void UART_Transmit(char *data) {
    HAL_UART_Transmit(&huart, (uint8_t *)data, strlen(data), HAL_MAX_DELAY);
}

Implement Data Reception

• Set up a function for receiving data, reading bytes from the receive data register.

 

• Again, choose between polling, interrupt, or DMA for data reception based on efficiency requirements.

Example of Receiving Data Over UART

void UART_Receive(char *buffer, uint16_t size) {
    HAL_UART_Receive(&huart, (uint8_t *)buffer, size, HAL_MAX_DELAY);
}

Test Your UART Communication

• Verify your code using a terminal emulator like PuTTY or Tera Term.

 

• Send and receive known data sequences to ensure data accuracy and reliable communication.

Debugging Tips

• If communication fails, check wiring connections and GPIO configurations.

 

• Use an oscilloscope or logic analyzer to diagnose signal integrity issues.

 

• Ensure the same baud rate and frame format are set on both communicating devices.