Honored Contributor
Honored ContributorMetastability was mentioned as one possible cause.
It is related to the present discussion because it precisely matches OPs behavior. I think you are on to something on the data transmission from JTAG as I have observed that the glitches occur in different signals at the same time - so JTAG signal integrity had occurred to me as well. I will try "read data" at my next opportunity. Thanks, SysTom --- Quote Start --- The previous discussion was about unconstraint and possibly too fast Signaltap clock rather than metastability. I explicitly mentioned that metastability won't cause fake signal transitions for stable signals. Not knowing any details about your design, it's impossible to relate it to the present discussion. I rarely see unexpected behavior of Signaltap. Few cases I remember are failure of trigger or storage qualifier logic with signals asynchronous to the Signaltap clock. I don't remember a case where a known stable signal showed fake transitions, except for situations where the acquired signal couldn't be correctly transferred due to JTAG signal quality issues. In the latter case, I got different recording each time the signal was retransmitted by pressing "read data". --- Quote End ---
