How to define a condition under which SignalTap would stop acquisition and pushed data through jTag without waiting for a storage buffer to be fully filled?
Thank you for your reply.
Unfortunately, it's no solution for me: I need to perform many acquisitions and SignalTap is controlled by tcl commands. As far as I know, tcl interface doesn't allow to stop the acquisition.
@sstrell: Thank you for the link. I overlooked the stop tcl command.
Anyway, it doesn't suit me well, as I would need to stop the acquisition arbitrary in the script. I basically want to open the acquisition window for a certain period (controlled by the trigger signal) and store (using storage qualifier) certain events occurring on the spied lines. The acquisition window is periodical (~1kHz) and I need to acquire events belonging only to a single acquisition window. What I miss, is a stop acquisition conditional logic in SignalTap which would start pushing data over jTag to PC.
You can certainly do this. You can either use conditional statements in Tcl (remember, it's a full scripting language that includes loops and conditionals; this is my favorite Tcl reference guide: http://tmml.sourceforge.net/doc/tcl/) or set up a state machine trigger in Signal Tap.
At the level of the tcl script, I don't have access to the trigger signal indicating the acquisition window. Moreover, software delays may be in this case just at the edge. However, the machine trigger in SignalTap would be a perfect solution. Unfortunately, I haven't found in the documentation how to set up a stop acquisition condition. Could you share with me some reference?
I tried the following state-based trigger:
state ST1: if (start_acq) goto ST2; state ST2: begin if( stop_acq && store ) begin start_store; stop_store; trigger 0; end else if (stop_acq) begin trigger 0; end else if (store) begin start_store; stop_store; end end
However, it doesn't work as expected:
EDIT: If I use `trigger 1`, it actually seems to work as intended. The only inconvenience is it needs to wait for an extra sample from the next acquisition window.