Pepper knob values in Pure Data

yannseznec

I recognize that the Pepper is fairly out of date these days, but I still enjoy using mine, so here's a question about it.

I've only just noticed that the values I'm getting on the knobs into my Pure Data patch go between about 0-0.91. That is to say, if I print the values coming from [adc~ 5], it will print values between about 0.0001 and 0.902. This isn't consistent across the knobs, for example [adc~ 10] gives me a range between 0.0001 and 0.939. is this normal?

It's likely it has been this way since I built it and I just never noticed!

giuliomoro

In order to protect the BeagleBone from Eurorack voltages and map 0V to 10V input voltage to the analog inputs' 0V to 4.096V range , there is a resistor divider at the input, where one of the two resistor is a potentiometer:

Potentiometers have a large tolerance and they can be up to 10% off from the nominal value. In many applications, that's not a big deal, but in this configuration it means that the maximum voltage at the potentiometer's wiper is limited by the actual resistance value of the potentiometer. So what you are measuring there is the combination of the tolerance on the resistor and the potentiometer: it's normal that it's different for each channel.