Help needed involving HC-SR04 Ultrasound Sensors

This seems like a fun project.

The source code I refer to from there is [this])https://github.com/BelaPlatform/Bela/blob/master/examples/06-Sensors/ultrasonic-distance/render.cpp). Wiring instructions are there and in the post you linked.

I understand you are familiar with Puredata and not so comfortable with C++, however I would recommend the following steps for you, which involve minimal tinkering with C++:

#1
remove at least one solenoid from your Bela, wire the sensor as described. Run the project and make sure everything works

#2

This implementation is using an analog out to the HC-SR04, because the latter requires a 5V input in order to work properly. To use the digitals, instead, you could replace the lines

analogWriteOnce(context, n / 2, gTriggerAnalogOutChannel, ...);

with

digitalWriteOnce(context, n, gTriggerDigitalOutChannel, ...);

after having declared and initialized gTriggerDigitalOutChannel and having called

pinMode(context, 0, gTriggerDigitalOutChannel, OUTPUT);

in setup() to initialize it as an output.

Once this is done, you could try to connect the sensor's TRIGGER input (which was previously connected to the analog pin ) to the digital pin defined in gTriggerDigitalOutChannel and check if it works.

#3
If the above does not work, it is probably because the digital out range is 0-3.3V and the TRIGGER input requires 5V. Therefore, you will need a simple amplifier to (e.g.: a transistor and a resistor) to amplify the signal from the digital output pin. Note: if your amplifier is inverting, you may have to swap HIGH with LOW in the digitalWrite() lines.

#4
Once you get it to work with the digital outputs at points #2 or #3, then you are ready to integrate this with PureData. Have a read here to get started, then you need to add the code from the project file you have been editing so far into a custom render.cpp file with puredata support:

• create a new Pd projet in the IDE, called MYPROJECT

• get the file in core/default_libpd_render.cpp and copy it into the project (e.g.: run the following in the terminal at the bottom of the IDE)

  cp core/default_libpd_render.cpp projects/MYPROJECT/render.cpp

• edit the render.cpp file in MYPROJECTby:

  • copying the relevant global variables from the modified HC-SR04 example file to the top of render.cpp
  • copying the content of setup() from the modified HC-SR04 example file to the top of setup() in render.cpp
  • copying content of render() from the modified HC-SR04 example file to the top of render() in render.cpp

• With the above changes, your render.cpp file will do the regular Puredata wrapping duties and also get new distance values from the sensors.
  • What is left to do is to send the distance read into Puredata. This can be done, for instance, adding a line like the following:

    	libpd_float("hcsr04_distance", distance);

    after the line where you compute distance. The line above will send the distance value to Pd, where it can be received with an object such as [receive hcsr04_distance] and used in your Pd patch.

Hopefully all the above should be doable for you: it's a matter of writing/editing 4/5 lines of C++ and then copy/paste them. Let us know how it goes.

That works for me. maybe add a rt_printf() statement next to libpd_float() to make sure the line is actually getting executed?

Something like

libpd_float("hcsr04_distance", distance);
rt_printf("Sending distance to pd\n");

Hmmm.
Is the name of the [receive] object in the Pd patch exactly the same as the one you are sending to from C++?
Maybe try to change both to hello so there is less chance of an error.

Also, try to connect your [receive] object directly to an oscillator (maybe after multiplying [* 10]), such as:

[receive hello]
|
[* 10]
|
[phasor~]
|\
|  \
[dac~]

just in case the message is being received but there is a problem with the printing.

If this still does not work, can you try to run:

examples/08-PureData/digital/_main.pd

connecting at least one button to one of the inputs and see if you receive those messages?