在双缓冲区交换期间处理 UART ISR

Question

我正在为 STM32F 处理器上的 UART 开发双缓冲区。以下示例在每次 UART ISR 运行时将数据添加到缓冲区。当主进程想要从中提取数据时，这个缓冲区就会被交换。

我担心可能出现的拐角情况。在我交换缓冲区之后但在我重置接收缓冲区计数之前，ISR 可能会触发。这意味着我的缓冲区大小和计数将不同步。

处理这种特殊情况的最佳方法是什么？

uint8_t rxBufferA[MAX_RX_BUFFER_SIZE];
uint8_t rxBufferB[MAX_RX_BUFFER_SIZE];
uint8_t *receivingBuffer;
uint8_t *processingBuffer;
volatile uint32_t rxBufferSize;

uart_isr() {
  receivingBuffer[rxBufferSize++] = RECEIVE_DATA_REGISTER
}


main() {

  receivingBuffer = &rxBufferA;
  processingBuffer = &rxBufferB;

  while(1) {

    if (rxBufferSize > 0) {
      uint32_t i = 0;
      uint8_t *ptemp = receivingBuffer;
      uint8_t bufferSize = 0;

      /* zero out processing buffer */
      memset(processingBuffer, 0, MAX_RX_BUFFER_SIZE);

      /* swap receiving and processing buffers */
      receivingBuffer = processingBuffer
      processingBuffer = ptemp;

      /* WHAT IF THE ISR FIRES HERE??? */         

      /* save off buffer size and reset count */
      bufferSize = rxBufferSize;
      rxBufferSize = 0;

      /* process rx data */
    } 
  }
}

Answer 1

你需要临界区。交换缓冲区时禁用用户中断。

顺便说一句，不需要归零

在双缓冲区交换期间处理 UART ISR

Handling UART ISR during double buffer swap

c

buffer

interrupt

stm32

uart