SPI MISO last bit set to 1 every few seconds

[avo]

 

the picture 1 shows correct miso data，but sometimes the last bit of miso was set to 1 like picture2

and the voltage will drop down slowly, even affect the next data

 other wires are no problem

the mcu is stm32f411ceu6 and spi1 is used between stm32 and ads1256

[STOne-32]

Dear @avo ,

check our errata here and try to apply the safe configuration.

https://www.st.com/resource/en/errata_sheet/es0287-stm32f411xcxe-device-errata-stmicroelectronics.pdf

 By decreasing the APB Frequency , Hope it helps you 

STOne-32

[avo]

I set the output level of the GPIO pin connected to the ADS1256's RESET pin  to High to solve the problem.Anyway thanks for you help.