Softpot ribbon controller

#62

My softpot (500mm) arrived in the mail recently and it's cool! One problem though - when I'm not touching it, it seems to think I'm pressing the lowest note possible somehow and the result is a really loud, low Humm sound...

I'm not doing the duotouch set up (I have the + going in one side pin, the signal attached to the center pin and the ground attached to the other side pin)

Anyone out there have a simple example patch that just lets me control an oscelators pitch....but with gate (like if I let go of the softpot I don't get a loud hummm)

I will give the person who provides this example patch exactly one TRILLION DOLLARS.

#63

I can't give you a patch... so save your money :sob:... when not touching it, it is floating and throwing values... so you need to set a threshold to overcome. Have a look at @mtyas contributions... I seem to recall he has some Axo ribbon patches (mine I wired all through Arduino with Midi out).

#64

Ahh coo. I have an Arduino Nano that I'm incorporating into my project actually...your Arduino code up online?

#65

@Androoclops my code isn't online and it probably wouldn't be understood by anyone but me, but there are lot's of resources available to get you going...
I started with this... http://www.coagula.org/albedo/coagula-midi-ribbon-controller-2-0-2/
Then read and tried some of this... http://synthhacker.blogspot.ca/2016/03/diy-midi-ribbon-controller.html
And settled with some rewritten pieces of this... https://github.com/316k/midi-ribbon-controller
:wink:

#66

The low hum seems normal. A soft pot always reads the lowest value, until you press somewhere higher, and as soon as you let go... bam it goes back to the lowest value. You use that feature as a gate, as soon as you press somewhere, your voltage is bigger than a certain value, so using a simple ">c" object, you can then send out a gate signal. I have an extra ribbon for pressure underneath for more expression (but that's something else)

here is a small easy patch that should work. You may need to filter out the signal before the gate, to get rid of the noise sometimes, but that's usual with GPIO's anyway.

Voila, hope you're enjoying the softpot, it's great when you start having fun with it

#67

Nice! Thanks man! Ill try it out tonight, I dig the YouTube channel btw!

#68

Oh, I just noticed something in your previous post about a second ribbon to detect pressure - I have one of those too! I haven't tried to use it yet though...definitely wanna figure out how it works though (I bought it off sparkfun)

#69

FYI, one thing I realized after my build and reading the datasheet for the fsr to detect pressure, which is typically mounted directly beneath the softpot... is that they have to 'breath'. That is, the free end should allow air to escape for proper performance. Coincidentally, the 3M 'tape' for the softpot at that free end was covering the air passage and I had to use a sharp knife to cut away some of it to keep the airway open... This is something better to do before sticking it down. You'll find that info in the datasheet for the fsr... it simply means cutting a small rectangle of the sticky tape from the end of the softpot before applying it over the fsr. How much it affects the performance I have no idea, but I wanted it 'right'.

#70

I had no idea about that! Thanks for the heads up!!

#71

Hey all, not sure if I should start a new thread here? I'm trying to use a 500m softpot for an axoloti project. I have the potentiomter setup with a simple gnd, pc0, vdda connected to its legs. When no pressure is applied to the potentiometer, the axoloti still reads some voltage received on pc0. When pressure is applied to the end, the voltage will drop all the way down to ~0. I'm wondering if anyone else experienced something similar and/or if anyone had a potential fix! Thanks

#72

this has been discussed multiple times, basically you want to hook it up in multitouchmode, search for other threads here on the forum

#73

Ahh, thanks for the response. To clarify, in single touch mode as I have it wired now, it's expected to have a non-zero voltage when not touched?

#74

yes. since the analog input is basically "floating" you get inconsistent readings.

#75

You must add a resistor between the VDDA and the softpot.
If you don't, when you press at both ends of the softpot at the same time you will cause a short circuit. It can damage the softpot and even burn your fingers.

#76

good point, but i think he will use the duotouch wiring anyhow now, since it is a pull-up circuit this problem is not existing there