No HDMI video output on PYNQ-z2 when Difference of Gaussians Application is tested

  • PYNQ version (3.01) & Board name(PYNQ-Z2) & Tool Version(2020.2):
  • bitstream (cv_dfx_4_pr.bit)


I was testing a jupyter notebook code from pynq_composable/applications/01_difference_of_gaussians_app.ipynb where cv_dfx_4_pr.bit overlay is used (GitHub - Xilinx/PYNQ_Composable_Pipeline: PYNQ Composabe Overlays).

I ran the code with a camera(Sony Handycam: 1080P) connected to HDMI input without an error but I got no video signal at the HDMI output(actually blank output at 720p). It looks like the HDMI input is working since app.start() command generates the block diagram output correctly.

I am trying to find out why I have blank signal at the HDMI output.
I generated the bit file twice to double check( 1st on Ubuntu 20,4 and 2nd time after upgrading Ubuntu to 22.04). During the 2nd attempt, there was a warning message like below, but not sure it’s related to the issue.

Built cv_dfx_4_pr successfully!

make: warning:  Clock skew detected.  Your build may be incomplete.

Thanks for help.

Hi @seung_kim,

Have you tried the prebuilt bitstreams?
Have you tried using a video source instead of the webcam?