Hi

I think the easier way to get info from the piezo is to plug it in a sound card preamp and then use [peakamp~ ]
Otherwise you should do a bit of electronics to transform the tiny AC voltage of the piezo output into a DC amplified voltage to match the analog input of arduino.
You'll have then to use [peakamp~] or something similar in arduino to be sure to take the highest value in a certain time, rather than take a "snapshot" of the analog input at the arduino clock frequency (like you would do for a knob)
The electronic part is not so difficult to build, I think you can get the schematic on the web.
Good luck

David

De : FernandoG <dataferx@gmail.com>
À : pd-list@iem.at
Envoyé le : Lun 20 septembre 2010, 17h 58min 29s
Objet : [PD] piezo sensor to pduino object

Hi

I need to use a piezo to trigger a bang in a pd patch but i am having some problem of inestability. I use the piezo like an analog input to arduino board, then comunicate with pduino ( firmata 2.1.) Once in the patch i use an arduino object to detect the signal from piezo and a threshold object to trigger a bang when the value of the signal goes up the threshold. The problem is the acuraccy of the sistem, because is really unprecise, sometimes trigger doestn work and some times trigger more bangs than hits to the piezzo.
Anybody knows a efficient way to do this? how can i improve the accuracy?

Thanks ¡¡