Hi all!

Hope you're doing well– I am currently working on a few sculptures that have speakers built into them. I am trying to move away from a simple media player and move towards an interactive system with a proximity sensor. I have a RPI4 with patchboxOS and an ultrasonic range sensor. I am trying to create a patch that increases in volume based off of how close someone is to the sensor. I've done a bit of digging but haven't been able to find anything current. Any suggestions?

In Arduino you would use the pulseIn() function, where you have to toggle the trigger pin, and then get the output of this function, which you have to multiply by 0.034 and divide by 2. This should give you the distance in cm. You might want to search the source code of this function and try to translate it to Pd or some Python script that will control Pi's GPIOs.

Great thanks-- I'm going to type out and share my process here in case anyone else is curious or has similar issues in the future.

I've gotten a Raspberry Pi 4 Model B to read distance in cm from this script here (https://tutorials-raspberrypi.com/raspberry-pi-ultrasonic-sensor-hc-sr04/)--

At this point I am going to try my hand at converting this script into a PureData object. After that I will try to use those values as an amplitude variable to send out to [dac~]. One foreseeable issue is that there are pretty dramatic value spikes in the python code when you move an object in front of the sensor (e.g. it will read 30cm, 1207cm, 11cm).

I'll report back later after a bit more digging.

** mini-update

I had to reset to RaspberryPi OS and manually install puredata extended 0.43.4 using this guide here (https://puredata.info/docs/faq/debian). From there I managed to get the cyclone extension to work but not py4pd--trying to figure out a workaround.

@kaimo Are you using the pure data pduino external with comport?

I've been working with both and getting extremely shaky data. Smooth works alright but doesn't help much.
The input, at least for vanilla, requires a fudiparse object. I'm working on alternatives and thinking, (hoping not) that i'm going to need to write a library to handle this better.

Also, curious why you use pdextended? I love plugdata's gui and search, etc, But for whatever reason I've been sticking to vanilla. I use Patchbox OS also on a Pi4 without their PiSound, although it looks great Im unsure of being locked into their hardware.

Im creating a live setup with what I have here (Pis and arduinos) but looking at the Bela on BBB has me considering jumping ship. Also the UDOO looks like a tremendous piece of gear.

I love audio sculpture, and hype to see what you make!

Just a note that getting access to the GPIOs of the Pi is not an easy task, if I'm not mistaken. You'd be rather better off working on the Python script to smooth out the spikes, rather than trying to implement this to a Pd external.
Also, cyclone should be available for Pi 4, so why use Pd-extended that is long gone?

Another little update here. Thanks to everyone for their feedback! I have found that python is the way to go for this project. Maybe down the line we'll have a GPIO object for all of our tinkering needs. I'm still working out some of the particulars in the code but I've managed to get the distance data and sound files playing. Separately I've, managed to control playback amplitude but connecting it to the live data is still proving challenging. Plus as objects get closer the value gets lower (should've seen that one coming).

Glad to see that there are sound sculpture fans out there -- everyone I've met interested in this stuff has only been lovely to work with and talk to.

@kaimo Hello, I'm very basic in Pure Data and Raspberry Pi and I also wanted to create a sound box that reacts to the approach of objects to generate sounds. After a few hours of research and chatting with ChatGpt I managed to create a simple prototype. To write the Python code I used PyCharm on the Raspberry Pi, bearing in mind that it is necessary to install libraries related to GPIO and OSC (since to communicate with Pure Data it is necessary to use netreceive). If I can help you, I'd be happy to share my experience with you. Here you go. Cheers and good work