Can SignalTap work without clock? I actually only want to see the logic values of the signals, which are not timed by clock (async resets, etc)
No, you must use clock for internal logic analyzer data acquisition to sample the data on the rising edge or falling edge etc.
Can you try use the global clock in your design and add the not timed signal into that stp file ?
I am sure in way above you can find the changes in not timed signal .
Also here is the signaltap user guide for your reference,
Thank you ,