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SPI4 Rx DMA doesn't work on STM32F4

Question asked by diverger on Sep 11, 2017
Latest reply on Sep 27, 2017 by Clive One

My tool chain is STM32F429 with STM32CubeMX, and MDK.


I'm using SPI4 to read data from a ADC, though I configure SPI4 as "duplex master",  I only need to read from it. When not using DMA, I call "HAL_SPI_Receive()" to read data. And there are clock output on SPI_SCK pin. But when I configure it to use DMA (DMA2 Stream 0, P2M, PSIZE = 16bit, MSIZE = 16bit), and after calling "HAL_SPI_Receive_DMA" nothing output on SPI_SCK pin.  As known, DMA only start after data received, so I don't think the problem is in my DMA configuration. The key point is why there is no clock output on SPI_SCK pin. 


It seems "HAL_SPI_Receive()" will send some dummy bytes to slave and at the same time read back some data. Won't  "HAL_SPI_Receive_DMA()" send dummy bytes?