Posted on May 17, 2011 at 13:08I am trying to read a block of data from a flash memory device
into the STM32 using SPI and DMA. What I noticed on the
o-scope is that when I write the command, 24-address, and dummy-byte
there is a clock from the MCU (SPI master mode). After
the last control byte (dummy) is sent, the read data is supposed
to be clocked back into the STM32 but I don't see any clock pulses.
I have the SPI device configured for DMA and the DMA engine
configured for the number of bytes to read. I never see
any data transferred though.
Here is my config:
/* SPI2 configuration */
SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;
SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;
SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_2;
SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
SPI_InitStructure.SPI_CRCPolynomial = 7;
SPI_Init(SPI2, &SPI_InitStructure);
DMA_DeInit(DMA_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&(SPI2->DR);
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)dma;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_BufferSize = 128;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA_Channel1, &DMA_InitStructure);
// Enable DMA channel1
DMA_Cmd(DMA_Channel1, ENABLE);
// tell the spi to use DMA
SPI_DMACmd(SPI2, SPI_DMAReq_Rx, ENABLE);
// enable spi device
SPI_Cmd(SPI2, ENABLE);
Any ideas how to get that clock to toggle?
Victor
