Hello everyone.
I'm just starting stm32f4. I'm try to use USART DMA, with Transmit it's ok. But with Receive, when I send characters from Terminal to Board first, for example 'aaa', it's ok. But the second characters I send, for example 'bbb', so the characters result is 'aaabbb' but I want the characters just 'bbb'. I'm try to clear the buffer but it's doesn't work.
Here is my code.
Pleas help me. Thank you so much.
int main(void)
{
USART_Config();
if (USART_GetFlagStatus(USART3, USART_FLAG_IDLE)==RESET)
{
/* clear buffer */
for (i=0; i<100; i++)
{
aRxBuffer[i]=0;
}
USART_Cmd(USART3, ENABLE);
DMA_Cmd(DMA1_Stream1, ENABLE);
USART_DMACmd(USART3, USART_DMAReq_Rx, ENABLE);
}
else if (USART_GetFlagStatus(USART3, USART_FLAG_IDLE)==SET)
{
USART_Cmd(USART3, DISABLE);
DMA_Cmd(DMA1_Stream1, DISABLE);
USART_DMACmd(USART3, USART_DMAReq_Rx, DISABLE);
}
while (1)
{
}
}
static void USART_Config(void)
{
USART_InitTypeDef USART_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
RCC->AHB1ENR = RCC_AHB1ENR_GPIOCEN;
RCC->APB1ENR = RCC_APB1ENR_USART3EN;
RCC->AHB1ENR = RCC_AHB1ENR_DMA1EN;
/* USART3 GPIO configuration -----------------------------------------------*/
/* Connect USART pins to AF7 */
GPIO_PinAFConfig(GPIOC, GPIO_PinSource10, GPIO_AF_USART3);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource11, GPIO_AF_USART3);
/* Configure USART Tx and Rx as alternate function push-pull */
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
GPIO_Init(GPIOC, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate = 56000;
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(USART3, &USART_InitStructure);
/* Configure DMA Initialization Structure */
DMA_InitStructure.DMA_BufferSize = 100;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable ;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_1QuarterFull ;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single ;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_PeripheralBaseAddr =(uint32_t) (&(USART3->DR)) ;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
/* Configure TX DMA */
DMA_InitStructure.DMA_Channel = DMA_Channel_4 ;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral ;
DMA_InitStructure.DMA_Memory0BaseAddr =(uint32_t)aTxBuffer ;
DMA_Init(DMA1_Stream4,&DMA_InitStructure);
/* Configure RX DMA */
DMA_InitStructure.DMA_Channel = DMA_Channel_4 ;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory ;
DMA_InitStructure.DMA_Memory0BaseAddr =(uint32_t)&(aRxBuffer);
DMA_Init(DMA1_Stream1,&DMA_InitStructure);
}
