I currently use standard peripheral library to write a driver that enable memory to USART6_TX DMA transfer on a STM32 F407 ZGT6 chip. However, I tried for a long time but the initialization keeps on failing: DMA_GetCmdStatus always returns DISABLE. By using GDB, I found that after the DMA_Init try to write configuration into DMA register, DMA CR register remains 0. The DMA initialize code and execution are as follow:
void DMA_USART6_Init(char* DMA_Start_Pos, uint32_t DMA_Buffer_Size){
DMA_Buffer_Size_GV = DMA_Buffer_Size;
DMA_Start_Pos_GV = DMA_Start_Pos;
/*RCC config*/
RCC_AHB1PeriphResetCmd(RCC_AHB1Periph_DMA2, ENABLE);
/*DMA init*/
//DMA_DeInit(DMA2_Stream7);
DMA_Cmd(DMA2_Stream7, DISABLE);
while ((DMA_GetCmdStatus(DMA2_Stream7) == ENABLE)){}
DMA_StructInit(&DMA_InitStruct);
DMA_InitStruct.DMA_Channel = DMA_Channel_5;
DMA_InitStruct.DMA_PeripheralBaseAddr = USART6_BASE + 0x04;//(uint32_t)&USART6->DR;
DMA_InitStruct.DMA_Memory0BaseAddr = (uint32_t) dubuff;//(uint32_t) DMA_Start_Pos;
DMA_InitStruct.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStruct.DMA_BufferSize = (uint16_t)sizeof(dubuff);//DMA_Buffer_Size;
printf("buffer size should be %d \r\n", (uint16_t)sizeof(dubuff));
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Circular;
DMA_InitStruct.DMA_Priority = DMA_Priority_High;
DMA_InitStruct.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_Init(DMA2_Stream7, &DMA_InitStruct);
printf("data counter after init %d \r\n", DMA_GetCurrDataCounter(DMA2_Stream7));
}
for the ENABLE code
void DMA_USART6_Enable_DMA(char* DMA_Start_Pos, uint32_t DMA_Buffer_Size, int MB){
Max_Buffer = MB;
USART6_init_for_DMA();
DMA_USART6_Init(DMA_Start_Pos, DMA_Buffer_Size);
DMA_USART6_NVIC_Init();
DMA_ITConfig(DMA2_Stream7, DMA_IT_TC, ENABLE);
DMA_Cmd(DMA2_Stream7, ENABLE);
while ((DMA_GetCmdStatus(DMA2_Stream7) == DISABLE)){}//program stucked in this loop
}
for the USART6 code:
void USART6_init_for_DMA(void){
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART6, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_USART6);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_USART6);
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
USART_InitStructure.USART_BaudRate = 57600;//115200;
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(USART6, &USART_InitStructure);
USART_Cmd(USART6, ENABLE);
USART_DMACmd(USART6, USART_DMAReq_Tx, ENABLE);
}
and the GDB result:
the value that should be written into DMA CR register
text in the picture 1:
367 DMAy_Streamx->CR = tmpreg;
(gdb) print tmpreg
$7 = 167904576
text in the picture2:
371 tmpreg = DMAy_Streamx->FCR;
(gdb) print *DMAy_Streamx
$10 = {CR = 0, NDTR = 0, PAR = 0, M0AR = 0, M1AR = 0, FCR = 0}
Please tell me if there is anything I can provide about my problem or things I can try further... Note: In the same program, my USART6 and GPIO works fine.
I am OP. At the start, I have a feeling that it could be an obvious mistake and that's true. It turns out that I should use RCC_AHB1PeriphClockCmd instead of RCC_AHB1PeriphResetCmd because OBVIOUSLY the later accessed RSTR (RCC Reset register) rather than ENR an thus clock is not enable (about that Codo is right).
Well, Hope guys whoever sees this question won't repeat this embarrass mistake ;(