Only getting "Code done running." on 64x64 LED Matrix Display with Matrix Portal

[dcliang]

Hello, all. Can someone please help me fix an issue of my LED matrix displaying "Code done running." instead of "Hello World!"?

My setup is a Matrix Portal plugged into a 64x64 LED Matrix (https://www.waveshare.com/wiki/RGB-Matrix-P3-64x64) with the Address E Line connected to Pin 8 and running CircuitPython 7.3.3. I'm currently running a simple code in an attempt to have the LED Matrix display "Hello World!", however, all I'm getting is "Code done running."

Attached a few images for reference. Thank you all in advance!

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Note: I'm a beginner and am attempting a LED Matrix project that will display the next 2 uptown and downtown arrival times for 7 different trains/buses near my apartment in Manhattan, New York. This has become a bit of an undertaking, even with reference code available from others who have completed similar projects. I started this project on 1/14/23.

[dastels]

The matrix seems to be working fine. I suspect the code. Please post the output from the REPL. It should provide more insight into what's going on.

Dave

[dcliang]

Thank you, dastels!! I'm completely new to this and didn't realize I can troubleshoot my code by running serial and seeing outputs from the REPL. I've now solved it by modifying code in line 7 based on the REPL response.

Thank you thank you!

[dastels]

The REPL is an invaluabvle tool for experimenting (you can type in code and have it executed immediately) and troubleshooting.

Dave

[dcliang]

I feel like I was missing a major piece of the puzzle until your note on REPL.

Is there a way to use REPL in Mu without connecting my microcontroller? No problem if not, but thinking it'd be easier if I can learn/test code without possibly messing up my microcontroller because I keep having it rerun/update. Attaching a screenshot of the error I'm currently getting when I try to pull up REPL against a copy of my code without the microcontroller connected to my computer.

[dastels]

No the "REPL" in Mu is just a serial terminal window. The REPL is part of the CircuitPython runtime. If you're experimenting with plain Python you can just use Python on your computer. The language is the same. If you want to test more CircuitPython specific code, you might be able to use Blinka depending on what computer you are running on. Something like Raspberry Pi will work. But the best is to use the actual hardware you will be using. I'm not sure why you need to rerun/update to experiment in the REPL.

Dave

[dcliang]

Got it, thank you! Figured that's the case but wanted to confirm.