Posted on June 01, 2011 at 14:45Hello,
I encountered problems when trying to send SPI data by means of DMA. It seems that DMA transfer never starts. The sequence of configurations commands is as follow:
1) Enable SPI and DMA clocks
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
2) Init of DMA
DMA_DeInit(cfg->txDMAChannel);
tmpreg |= DMA_PeripheralDataSize_Byte | DMA_MemoryDataSize_Byte | DMA_Mode_Normal | DMA_Priority_VeryHigh | DMA_MemoryInc_Disable | DMA_M2M_Disable| DMA_DIR_PeripheralDST;
cfg->txDMAChannel->CCR = tmpreg;
3) SPI initialization
SPI_DeInit(cfg->SPIx);
cfg->SPIx->CR1 = 0x002F; //BR == 5; MSTR, CPOL, CPHA == 1
cfg->SPIx->CR2 = 0x03; //SPI_CR2_TXDMAEN;
4) Enable SPI
cfg->SPIx->CR1 |= 0x40;
6) Enable DMA irq in NVIC
7) Transaction (transmission) is started as follows
DMA_Cmd( cfg->txDMAChannel, DISABLE);
cfg->txDMAChannel->CMAR = (u32)tr->txBuf; //tx buffer ptr
cfg->txDMAChannel->CPAR = (u32)&cfg->SPIx->DR; //SPI DR reg addr
cfg->txDMAChannel->CNDTR = (u32)tr->len; //4
tmp = txDMA->CCR & 0xFF70; /* Clear flags: MINC, TEIE, HTEIE, TCIE, EN */
tmp |= DMA_MemoryInc_Enable | DMA_IT_TE | DMA_IT_TC;
cfg->txDMAChannel->CCR = tmp;
DMA_Cmd(txDMA, ENABLE);
Now I suppose the transaction should get started and after the last send byte, DMA irq should be called out. But nothing like this happens.
When I try to send data without DMA, SPI irq is always called out when TxE is set.
The contents of the relevant registers right after the transaction starts is as follows
DMA_CCR6 == 0x0000309B
DMA_CNDTR == 4
DMA_CPAR ==0x4001300C
DMA_CMAR ==0x200000D4
SPI1_CR1 == 0x6F //BR=5;MSTR, CPOL, CPHA ==1
SPI1_CR2 == 2 // TXDMAEN
SPI1_SR == 2 //TxE
I'll be grateful for any advice or hint.
Thank you
