 
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
Dear @avo ,
check our errata here and try to apply the safe configuration.
By decreasing the APB Frequency , Hope it helps you
STOne-32
