keil5rs485接受u16数据

以下是在 Keil μVision5 中使用 RS485 接收 16 位数据的示例代码：

#include <stdio.h>
#include <stdint.h>

#define BUFSIZE 64

volatile uint16_t data_received = 0;
volatile uint8_t rx_buffer[BUFSIZE];
volatile uint8_t rx_wr_index = 0;
volatile uint8_t rx_rd_index = 0;
volatile uint8_t rx_counter = 0;

void USART_IRQHandler(void) {
  uint16_t rx_data;
  
  if ((USART1->SR & USART_SR_RXNE) != 0) {  // Received data is ready to be read
    USART1->SR &= ~USART_SR_RXNE;           // Clear the RXNE flag
    rx_data = (uint16_t)(USART1->DR & 0x01FF);
    if (rx_counter < BUFSIZE) {             // Check if buffer is not full
      rx_buffer[rx_wr_index++] = (uint8_t)rx_data;  // Store the received data in buffer
      rx_wr_index %= BUFSIZE;
      ++rx_counter;
    }
  }
}

void receive_data(void) {
  while (rx_counter > 1) {  // Check if buffer has at least 2 bytes of data
    if (rx_buffer[rx_rd_index] == 0xAA && rx_buffer[(rx_rd_index + 1) % BUFSIZE] == 0xBB) {
      // Start of data frame
      data_received = ((uint16_t)rx_buffer[(rx_rd_index + 2) % BUFSIZE] << 8) | rx_buffer[(rx_rd_index + 3) % BUFSIZE];
      rx_rd_index += 4;
      rx_rd_index %= BUFSIZE;
      rx_counter -= 4;
    } else {
      // Not start of data frame, discard the first byte and shift buffer by 1 byte
      rx_rd_index += 1;
      rx_rd_index %= BUFSIZE;
      --rx_counter;
    }
  }
}

int main(void) {
  USART_InitTypeDef USART_InitStructure;
  
  // Enable USART1 clock
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

  // Configure USART1 pins
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);  // PA10 = USART1_RX
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);   // PA9 = USART1_TX
  GPIO_InitTypeDef GPIO_InitStructure;
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

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

  // Enable USART1 interrupt
  NVIC_EnableIRQ(USART1_IRQn);

  // Enable USART1
  USART_Cmd(USART1, ENABLE);

  while (1) {
    receive_data();
    if (data_received != 0) {
      // Do something with received data
      printf("Received data: %u\n", data_received);
      data_received = 0;
    }
  }
}

在上面的代码中，我们使用了 USART1 来接收 RS485 数据，接收到的数据存储在一个缓冲区中，直到缓冲区中有至少 2 字节的数据时，我们才开始检查是否接收到了一个完整的数据帧。在本例中，我们假设帧起始标志为 0xAA 和 0xBB，数据帧中紧随起始标志后的 2 个字节为 16 位数据。如果检测到起始标志，我们从缓冲区中读取 2 个字节作为数据，并清除已读取的数据。如果没有检测到起始标志，则将缓冲区中的第一个字节丢弃，并将缓冲区中的数据向左移动一个字节。最后，我们可以在主循环中处理接收到的数据。