SPI Receive - pulse in MOSI line

[sreyas40]

The above image represents logic analyzer output when HAL_SPI_Receive_DMA is executed. My doubt is regarding the single high pulse at MOSI line. During HAL_SPI_Transmit_DMA , no issues. Is this normal behaviour? STM as Full duplex master, i have disconnected the slave to check if it was responsible for the high pulse.

[Andrew Neil]

Please show your code.

How to insert source code

[AScha.3]

For a Full duplex master you should always use TransmitReceive , as the SPI shifts out and in same time.

or with dma:   HAL_SPI_TransmitReceive_DMA( ..)

(only receive on full duplex is like : receive and dont care about transmit... :)

It might send anything, maybe the remains from last receive, as you write nothing to send.)

[Ozone]

MOSI is "Master Out Slave In".
What you see on this line is what was written by your code to the SPI Tx register beforehand.