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Code get stuck at

arun rajajinagar
Associate II


I am using STM32L072 LoRa discovery kit and enabled UART with DMA. Some times my code gets stuck in HAL_UART_Receive_DMA( ....) function at the line 

SET_BIT(huart->Instance->CR3, USART_CR3_EIE);

This is called at the begining of the code. It wont recover at all until i reset the MCU for some number of times.

Kindly let me know how shall I resolve this issue.

Senior II

Probably this happens because one error flag is set when you call  HAL_UART_Receive_DMA(). You must clear the flags first.

Try this:


  uint32_t primask_bit;
  primask_bit = __get_PRIMASK();
  // HAL_UART_Receive_DMA() will enable the Error interrupt. If any of the ORE, FE, PE flags are set there will be an
  // interrupt.

  // Clear the flags that could cause an interrupt when HAL_UART_Receive_DMA() enables the error interrupt
  huart1.Instance->ICR = USART_ICR_FECF | // Framing Error Clear Flag
                         USART_ICR_NCF |  // Noise detected Clear Flag
                         USART_ICR_ORECF; // OverRun Error Clear Flag

  // Enable DMA to receive all bytes into a circular buffer
  HAL_UART_Receive_DMA(&huart1, (uint8_t *)uartCircularRxBuffer, sizeof(uartCircularRxBuffer));

  // Turn off Error Interrupt Enable. This will disable ORE, FE, PE interrupts
  huart1.Instance->CR3 &= ~USART_CR3_EIE;

  // Re-enable the interrupts: restore previous priority mask