SPI Signal Shape Issue

[AE104]

Hello,

I am try to control an external DAC system with the SPI interface. The clock signal shape looks like the attached file. I didn't figure out the meaning of the signal. Yellow is the clock signal and the blue is CS signal.

[AE104]

I pressed the CLEAR and AUTO, now the sampling rate is 250 MSa/s with 300k pts.

[Tesla DeLorean]

The bandwidth of the isolator is 25 Mbps

Is the signal on the STM32 side clean? Not ringing?

If the traces are short, ease back the slew-rate via SPEEDR settings.

What speed is your SPI clocking at?

[AE104]

Now the updated signals look like the attached figures (the isolator removed).

The SPI Baudrate 10.5 Mbits/s.

[AScha.3]

better.

probe still at x1 ! you cannot test cmos connections at > 10MHz with x1 probe setting.

set x10 at probe switch and in scope menu.

[AE104]

I set the 10x both the probe and settings in the oscilloscope.

[AScha.3]

x10 probe setting needs adjustment - did you adjust ?

+ BW limit 20 M is set.

do you make some game here ? who is the biggest idiot ? or what ?

sorry.

want help - or play game ?

[AE104]

No game. What adjustment do I need?

[AScha.3]

bw limit off.

and adjust probes - i hope you know how to do.

[AE104]

Yes I did it.