Lập trình UART STM32

Đối với STM32F4 có đến 6 bộ UART 1,2,3,4,5,6

Để giao tiếp với các thiết bị như HMI Công nghiệp có thể dùng MAX3232IDR hoặc ADUM3251 ISO cách lý GND 

Bạn có thể kết hợp ADUM1201 Kết hợp với MAX3232

Hoặc các bạn có thể dùng UART to PC như PL2303,CH340..

Các chân UART STM32F4

Hàm cài đặt UART 

void USART_Config(void)
{
    // Enable clock for GPIOB
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
    // Enable clock for USART1
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    // Connect PB6 to USART1_Tx
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_USART1);
    // Connect PB7 to USART1_Rx
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_USART1);

    // Initialization of GPIOB
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOB, &GPIO_InitStruct);

    // Initialization of USART1
    USART_InitTypeDef USART_InitStruct;
    USART_InitStruct.USART_BaudRate = 9600;
    USART_InitStruct.USART_HardwareFlowControl =
            USART_HardwareFlowControl_None;
    USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_InitStruct.USART_Parity = USART_Parity_No;
    USART_InitStruct.USART_StopBits = USART_StopBits_1;
    USART_InitStruct.USART_WordLength = USART_WordLength_8b;
    USART_Init(USART1, &USART_InitStruct);

    // Enable USART1
    USART_Cmd(USART1, ENABLE);
}

Các hàm truyền nhận UART

void USART_PutChar(char c)
{
    // Wait until transmit data register is empty
    while (!USART_GetFlagStatus(USART1, USART_FLAG_TXE));
    // Send a char using USART1
    USART_SendData(USART1, c);
}

void USART_PutString(char *s)
{
    // Send a string
    while (*s)
    {
        USART_PutChar(*s++);
    }
}

uint16_t USART_GetChar()
{
    // Wait until data is received
    while (!USART_GetFlagStatus(USART1, USART_FLAG_RXNE));
    // Read received char
    return USART_ReceiveData(USART1);
}

Code program:

#include "stm32f4xx.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_gpio.h"
#include "stm32f4xx_usart.h"

int main(void)
{
    // Enable clock for GPIOD (for orange LED)
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

    // Initialization of GPIOD (for orange LED)
    GPIO_InitTypeDef GPIO_InitDef;
    GPIO_InitDef.GPIO_Pin = GPIO_Pin_13;
    GPIO_InitDef.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitDef.GPIO_OType = GPIO_OType_PP;
    GPIO_InitDef.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitDef.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOD, &GPIO_InitDef);

    // Call USART1 configuration
    USART_Config();

    // Send "Hello, World!" to PC
    USART_PutString("Hello, World!\n");

    while (1)
    {
        // Get a char from PC
        uint16_t data = USART_GetChar();

        if (data == 'H')
        {
            // If received char is 'H' then turn on orange LED
            GPIO_SetBits(GPIOD, GPIO_Pin_13);
        }
        else if (data == 'L')
        {
            // If received char is 'L' then turn off orange LED
            GPIO_ResetBits(GPIOD, GPIO_Pin_13);
        }
    }
}