Logictools generators fail when run

Support
1

PYNQ-Z1 Board with v3.0.1 from downloaded image.

When running the fsm_generator.ipynb and pattern_generator_and_trace_analyzer.ipynb, the captured waveforms are incorrect when calling the run method. For FSM, the state machine advances twice per clock cycle, but works properly when stepped through the logictools_controller (see below incorrect output, when the commented code is run instead, output is correct). Similarly, the pattern generator loopback signals are all 0 when run, but work fine when stepped.

I haven’t been able to determine if this is an issue with my specific board (no spare boards to test), or whether this is an issue with the software/overlay within PYNQ, so any insight would be helpful.

fsm_generator_run
fsm_generator_run1128×411 36.7 KB

2

After digging into the code a bit, it looks like the only difference between a run and a step is the command being written to the MicroBlaze. From pynq.lib.logictools.fsm_generator.py:

def run(self):
...
cmd_run = CMD_RUN | FSM_ENGINE_BIT
        if self.analyzer is not None:
            cmd_run |= TRACE_ENGINE_BIT
        self.logictools_controller.write_command(cmd_run)
...

vs

...
def step(self):
cmd_step = CMD_STEP | FSM_ENGINE_BIT
            if self.analyzer is not None:
                cmd_step |= TRACE_ENGINE_BIT
            self.logictools_controller.write_command(cmd_step)
...

which leads me to believe that this might be an issue with the overlay itself, but without access to the detailed design of the overlay I don’t think I can verify this.

3

Hi @gweesip,

Welcome to the PYNQ community.

You can find and rebuild the loogictools overlay from here PYNQ/boards/Pynq-Z1/logictools at master · Xilinx/PYNQ · GitHub

Mario

4

Thanks. I’m not quite at the point of building overlays for PYNQ, but I’ll definitely give that a try when I get there. If I get to the root cause before anyone else chimes in here, I’ll be sure to update.