Disabling Uart4 interrupt causes lockup

Posted on August 27, 2017 at 00:02

Hello Forum,

I have a function that I call to read data from Uart4. As there are a number of critical times that I need Uart4 interrupt disabled, I enable the interrupt on entry to the function and disable it after priocessing the uart data. However, I found that the

system locks up after executing the NVIC_DisableIRQ(USART3_8_IRQn) command. I've tried many things but I cannot seem to get it working. My code is as follows. Any help greatly appreciated.

 

 Kind Regards

 Bob

void Enable_Usart4_Interrupts(void)

{

  NVIC_EnableIRQ(USART3_8_IRQn);                

}

void Disable_Usart4_Interrupts(void)

{    

  NVIC_DisableIRQ(USART3_8_IRQn);    

}

void Usart4Init_RS485(void)

{      

  USART_InitTypeDef USART_InitStructure;

  GPIO_InitTypeDef GPIO_InitStructure;

  NVIC_InitTypeDef NVIC_InitStructure;

    

  // Enable GPIOC and DMA clock

  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC, ENABLE);

        

  // Enable USART4 APB clock

  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART4, ENABLE);

        

 

  // Connect pin to Periph

  GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_0);   //  USART4 TX

  GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_0);   //  USART4 RX

 

  // Configure pins as AF pushpull

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;

  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(GPIOC, &GPIO_InitStructure);

      

  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(USART4, &USART_InitStructure);

        

  USART_Cmd(USART4, ENABLE);

            

//  Enable the COM4 Receive interrupt: this interrupt is generated when the

//  COM4 receive data register is not empty

  USART_ITConfig(USART4, USART_IT_RXNE, ENABLE);

  // USART4 IRQ Channel configuration

  NVIC_InitStructure.NVIC_IRQChannel = USART3_8_IRQn;    

  // USART4 IRQ Channel priority     

  NVIC_InitStructure.NVIC_IRQChannelPriority = 0;    

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  NVIC_Init(&NVIC_InitStructure);       

 }

 

 

 void USART3_8_IRQHandler(void)

{

uint8_t rx_byteby = 0;

        

USART_ClearITPendingBit(USART4, USART_IT_RXNE);      //Clear any pending uart interrupts bits        

                 

  while (USART_GetITStatus(USART4, USART_IT_RXNE) != RESET) // Received characters modify string

         {                

        rx_byteby = USART_ReceiveData(USART4);

       rx_str[U4_rx_count++] = rx_byteby;                        

        }

}

int Read_From_Uart4(void)

{       

Enable_Usart4_Interrupts();   // Enable Usart4 interrupts for Uart4 data

    

// Receive and process UART4 data

//    .....

// ...

Disable_Usart4_Interrupts();  // Disable Usart4 interrupts          

}