stm32 DMA cannot send data to SPI1 DR (Cannot use DMA to send data to SPI)

3
votes

I am trying to use DMA to send data to SPI1. SPI1 will then control DAC for voltage update.

The chip used is STM32F407. Therefore, the corresponding channel/stream is： channel3/stream5, as is shown in reference manual. However, when the DMA is enabled, no data is shown in SPI1->DR and there are no results shown in the oscilloscope.

The SPI works fine when SPI1->DR is written by software. Could anyone help to check out what has happened? Here comes the code:

uint16_t DACData[1]; 
void InitDMA(void)
{
    DMA_InitTypeDef DMA_InitStructure;
    DMA_Cmd(DMA2_Stream2, DISABLE);
    while (DMA2_Stream2->CR & DMA_SxCR_EN);
    //SPI1 Tx DMA
    DMA_DeInit(DMA2_Stream5);
    DMA_StructInit(&DMA_InitStructure);
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE); //Init DMA clock
    DMA_InitStructure.DMA_Channel = DMA_Channel_3;//SPI1 Tx 
    DMA_InitStructure.DMA_PeripheralBaseAddr  = (uint32_t)&(SPI1->DR); //Set the SPI1 Tx
    DMA_InitStructure.DMA_Memory0BaseAddr  = (uint32_t)&DACData;       //Set the memory location
    DMA_InitStructure.DMA_DIR  = DMA_DIR_MemoryToPeripheral;           //
    DMA_InitStructure.DMA_BufferSize  = 1;            //Define the number of bytes to send
    DMA_InitStructure.DMA_PeripheralInc  = DMA_PeripheralInc_Disable;             
    DMA_InitStructure.DMA_MemoryInc  = DMA_MemoryInc_Disable;            
    DMA_InitStructure.DMA_PeripheralDataSize  = DMA_PeripheralDataSize_HalfWord;    
    DMA_InitStructure.DMA_MemoryDataSize  = DMA_PeripheralDataSize_HalfWord;        
    DMA_InitStructure.DMA_Mode  = DMA_Mode_Normal;               //Normal mode (not circular)
    DMA_InitStructure.DMA_Priority  = DMA_Priority_High;                
    DMA_InitStructure.DMA_FIFOMode  = DMA_FIFOMode_Disable;  //Operate in 'direct mode' 
    DMA_InitStructure.DMA_MemoryBurst =DMA_MemoryBurst_Single;
    DMA_InitStructure.DMA_PeripheralBurst =DMA_PeripheralBurst_Single;
    DMA_Init(DMA2_Stream5, &DMA_InitStructure); //DMA2, Channel 3, stream 5

    //Enable the transfer complete interrupt for DMA2 Stream5
    DMA_ITConfig(DMA2_Stream5, DMA_IT_TC, ENABLE);                                       
}

Here is how SPI1 initialized

void InitSPI1(void) 
 {
    GPIO_InitTypeDef GPIO_InitStruct;
    SPI_InitTypeDef SPI_InitStruct;
    // enable clock for used IO pins
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    // connect SPI1 pins to SPI alternate function
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1); //SCK
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1); //MISO
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1); //MOSI
    // enable peripheral clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

    /* configure SPI1 in Mode 0 
     * CPOL = 0 --> clock is low when idle
     * CPHA = 0 --> data is sampled at the first edge
     */
    SPI_InitStruct.SPI_Direction = SPI_Direction_1Line_Tx; // one line transmission
    SPI_InitStruct.SPI_Mode = SPI_Mode_Master;     // transmit in master mode, NSS pin has to be always high
    SPI_InitStruct.SPI_DataSize = SPI_DataSize_16b; // one packet of data is 16 bits wide
    SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle
    SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge
    SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set;; // set the NSS management to hardware
    SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_256; // SPI frequency is APB2 frequency / 4 = 21MHz
    SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first

    SPI_Init(SPI1, &SPI_InitStruct); 
    SPI_Cmd(SPI1, ENABLE); // enable SPI1
}

I try to use these commands to start DMA:

DACData[0]=0xff00;
DMA_Cmd(DMA2_Stream5, ENABLE);

In case it may help, here comes the register values for DMA2, Stream 5 enter image description hereenter image description here

4
stm32spidmastm32f4discovery

4 Answers

5
votes

Such a line has been missed:

SPI_I2S_DMACmd(SPI1, SPI_I2S_DMAReq_Tx, ENABLE);

It enables SPI1 to use the DMA.

1
votes

Just to add:

If you want to restart DMA, it seems you'll have to call not just:

DMA_Cmd(DMA2_Stream5, ENABLE);

but

DMA_ClearFlag(DMA1_Stream5, DMA_FLAG_TCIF5);

as well. Even though I didn't enable interrupts it seems this is still required.

0
votes

Based on a quick look, the first thing that stands out is that you try to use parts of the DMA peripheral before enabling it. Try moving the

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2, ENABLE);

call before

DMA_Cmd(DMA2_Stream2, DISABLE);
while (DMA2_Stream2->CR & DMA_SxCR_EN);

as it could be eg. getting stuck in the loop. (I'm not sure which way the bits get read if the peripheral is not enabled when reading its registers)

If that doesn't help, leave a comment and I can try looking at it a bit more closely later.

0
votes

I had a problem but nothing on the internet could help me, my solution was to change this;

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;

Other than that, my code is almost simliar, I don't get why yours would work.