Thanks Retrolefty for the reply. Once again, I stumble onto my ancestral issue on plotting software... shame on me, after a good half an hour I ended up with the horrible images attached.
And for the code, I use Firmata with some modifications to have "clean" data coming from PIN A0~A2:
(code exceed maximum post size, will attach as file)
Hope this could help... thanks a lot!
firmata_mod.txt (22.8 KB)