Crash when selecting LA pin in multimeter

[bessman]

When turning the multimeter to any of the LA pins for frequency measurement or pulse count, communication desyncs and the app crashes.

Note that the GET_FREQUENCY command is not implemented in the v3 firmare: https://github.com/fossasia/pslab-firmware/blob/37b91ab961409715fbfe7159a6a5aba1a0c3e364/src/commands.c#L252

In pslab-python, the frequency measurement is implemented using the logic analyzer functions: https://github.com/fossasia/pslab-python/blob/8ae580effcddaf4d341e66098a96beab77f86b3d/pslab/instrument/logic_analyzer.py#L88

[AsCress]

@bessman Thanks for testing ! I couldn't reproduce this on any of the platforms. On which platform did you observe this issue ?

Note that the GET_FREQUENCY command is not implemented in the v3 firmware

Yeah ! We had a talk about this earlier. In the flutter app, I've implemented frequency measurement in the same way as pslab-python, i.e., using logic analyzer functions.

[bessman]

Linux. Here is the debug output: https://gist.github.com/bessman/121839c77c8569c07a8b7595c3801058

[bessman]

I've tested this on Android now as well, and selecting one of the LA channels in multimeter appears to desync communication there as well.

Test procedure:

1. Reset PSLab
2. Open pslab-app
3. Select multimeter instrument
4. Move selector wheel between LA1 and LA2 a few times
5. Close multimeter instrument
6. Open oscilloscope instrument
7. Select CH1

Observation:

No output, or very buggy output, from CH1.

Other instrument also do not work, or work unreliably, after using LA channels in multimeter.

System: Android 15
pslab-app version: 4.11.0 from Play store beta track