Hello, i am working on a patch that should control the volume of 2 tracks via serial data.

Let me explain what i would like to achieve.

I have 3 wav-files. Each ~3min long, playing in an infinite loop.
The first track is always hearable the other two track should be faded in and out using two switches connected to an arduino and communicating with Pure Data over the serial port.

My problem is that if i flip the switch to "on" i have an "1" coming in over the serial port that is not triggering a bang but keeps the bang active all the time, same with the "0" coming over the serial port.
That way the fade-in and out is not working as it should.

How do i trigger the bang without keeping the bang active all the time?
Thanks!

if i flip the switch to "on" i have an "1" coming in over the serial port that is not triggering a bang but keeps the bang active all the time, same with the "0" coming over the serial port.

The Arduino keeps on sending 0s or 1s
Easiest would be to insert the object
[change]
filtering duplicates once before [sel 1] and [sel 0]

But there might be more different data coming in. Then prefilter with another [sel 0 1]

Also consider that by pressing or releasing the switch bounces until it keeps resting at its actual state. To debounce nervous switch data:
https://forum.pdpatchrepo.info/topic/12092/debouncing-was-measure-time-between-two-bangs-events
https://forum.pdpatchrepo.info/topic/6257/debouncing/2

But wait:
Is the part following after [comport] working?
Also [list tosymbol] followed by [fromsymbol] looks redundant to me?
Did you debug with another [print later] after [fromsymbol] comparing with that [print] earlier on?

Some more notes on your patch:

Better use [line~] or [vline~] with tilde ~ instead of [line] because signalrate objects update their output on every sample, control objects only every 64th sample.

Squared for logrithmic fades:

[line~] has to reach 1 for this. You can divide the signal later on: [*~ 0.25]