[ARM] STM32 UART Rx with DMA

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#include<stm32f10x.h>
uint8_t rx_data[13];
 
 
void USART3_config(void)
    {
        RCC->APB1ENR |= RCC_APB1ENR_USART3EN;
        RCC->AHBENR |= RCC_AHBENR_DMA1EN;
 
        USART3->BRR = 0x0EA6;  //for 9600 baurd rate
        USART3->CR1 |= USART_CR1_TE | USART_CR1_RXNEIE | USART_CR1_RE;
        USART3->CR3 |= USART_CR3_DMAT | USART_CR3_DMAR ;
        USART3->CR1 |= USART_CR1_UE;
        NVIC_EnableIRQ(USART3_IRQn);
    }
 
void USART_DMA_RX_init(void)
{
  RCC->AHBENR |= RCC_AHBENR_DMA1EN;
  DMA1_Channel3->CPAR = (uint32_t)&USART3->DR;
  DMA1_Channel3->CMAR = (uint32_t)rx_data;
  DMA1_Channel3->CNDTR = 20;
  DMA1_Channel3->CCR |= DMA_CCR3_MINC | DMA_CCR3_TCIE | DMA_CCR3_HTIE  ;
  DMA1_Channel3->CCR |= DMA_CCR3_EN;
  NVIC_EnableIRQ(DMA1_Channel3_IRQn);
}
 
int main(void)
{
  RCC->APB2ENR |= RCC_APB2ENR_IOPBEN | RCC_APB2ENR_AFIOEN;
  GPIOB->CRH = 0x00008B00;
  USART_DMA_RX_init();
  USART3_config();
 
 while(1)
 {
 
 }
}
 
void DMA1_Channel3_IRQHandler(void)
{
  if((DMA1->ISR & DMA_ISR_HTIF3) == DMA_ISR_HTIF3)
  {
    DMA1->IFCR = DMA_IFCR_CHTIF3;
  }
  else if((DMA1->ISR & DMA_ISR_TCIF3)== DMA_ISR_TCIF3)
  {
    DMA1->IFCR = DMA_IFCR_CGIF3 | DMA_IFCR_CTCIF3;
  }
}
void USART3_IRQHandler(void)
{
  if((USART3->SR & USART_SR_RXNE) == USART_SR_RXNE)
  {
    USART3->SR &= ~ USART_SR_RXNE;
  }
}