SPI_MOSI pin does not drive a certain logical level in SPI master mode

[Yang Yang]

Hello, ST experts

 

PB3&PB4&PB5 pins are configured to SPI_SCLK,SPI_MISO,SPI_MOSI in STM32U595VIT6. The code framework is generated according to CubeMX. It works well when communicating with its partner(TI's 32bit ADC), and HAL_SPI_Receive() is called when ADC's interrupt happened, there are no transmit opeartions all the time. The ADC need a clean SPI_MOSI signal when the chip select pin is enabled, but it seems that this pin is not driven to a certain state as the picture below.  
And when the PB5 is set to GPIO, the signal is much more different from this. It is very clean. So I want to know how to set SPI_MOSI to a certain state when operating SPI.

 

 

BR

Yang

[Bassett.David]

Hello,

The scope signal looks like the scope input mode is AC-coupled...