Connect the Saleae probe means pull-down?

I had SPI issue, the waveform is good with other scope(LeCroy) but malfunction.

But when I connect the SCK with Saleae probe, then the function suddenly turn to PASS.
What’s the Saleae probe inside?
Is that meaning I connect SCK with pull-down?

Could anyone comment on this?


@alex925chen Can you confirm which exact Saleae Logic model you own?

You can take a look at the datasheet for your specific device to get the input impedance values.

It would also be good to know the following:

  • How is your Saleae Logic connected to your DUT?
  • How are your SPI signal traces laid out on your PCB?
  • What is the input impedance of the LeCroy scope probes that you are using? It might be good to compare to ours to see what might be causing the difference.
  • Does your DUT pass without any probes attached?