Print out digital pin data

dbrode

Hi! I'm fairly new to both pd and bela, and I'm trying to read data from an ultrasonic sensor (HC-SR04) with digital pins (I got it to work in C++ with chaning the trigger analog to digital instead, which is why both are digital - not sure if one should be digital and the other analog in pd). I've read through the examples and blog post about it, but can't quite get it to print the values out. I'm not sure if I'm even close to get it correct but would really appreciate some help =)
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giuliomoro

1- You are missing the [loadbang] on the messages that go into [s bela_setDigital]
2- you are trying to read the digital in with [adc~ 11], but that would require setting them at audio rate, e.g.: [in 11 ~(.
If you want to use them at control rate, use [in 11(, you would then receive the inputs with the corresponding receiver, e.g.: [r bela_digitalIn11]

dbrode

giuliomoro I want to use the values to control an audio effect (in my case a lpf). I changed it to this and now it prints out that "channel 1 is set as input at message rate" and "channel 0 is set as output at message rate" but I'd like to have the values from the ultrasonic sensors.

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I also tried this (pic below) but it gives me the same outcome as above.

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giuliomoro

right, so you can either:

combine the existing C++ example with Pd. The basic principles are explained here, and a number of attempts have been made previously, e.g.: here, here,
do the detection in Pd, using by computing the time difference between when you send out the trigger and when you receive the "echo" response. This is straightforward to do when using the digitals at message rate, however in that case the timing resolution is more coarse, as messages are only sent once every 16 samples, and the spatial resolution of the sensor is similarly reduced. You could use some sort of audio-rate sensing, in Pd, but I am not sure how you could achieve that.

dbrode

giuliomoro Thank you so much! The second one did the job for me =)

giuliomoro

great, can you post your code?

dbrode

giuliomoro Of course! It's here: https://github.com/chiinifli/Ultrasonic-sensors-c-to-pd

So far it works with 2 ultrasonic sensors. It's gonna be used to create an expressive (large gestures to control it) granular synthesizer. Now I need to map the values to control a lpf. I'll try to update it and hopefully post the final result in the near future =)

giuliomoro

I see you have two Scope objects, but actually you should not have them:

they are not needed for the sensor to work. They were in the example code just to visualize the signal
there can only be one Scope object at a time, and there already is one used by the default_libpd_wrapper ( the one that you had to comment out)

dbrode

giuliomoro oh thank you so much. I'll update the code tomorrow