Hi there.

I can't figure out how to retrieve distance data from the HC- SR04 sensor. I am using Pduino as the interface between PD and arduino. As it's digital pins that the sensor is routed to, I am having difficulty understanding how I can get analogue type data from them?

Any tips would be much appreciated!

This is quite common with this sensor and Pduino. In the code one can find for this sensor you can see that it uses the Arduino native pulseIn() function, which is called when the echo pin sends a signal to the Arduino. In order to use this sensor with Pduino you need to translate the workings of this function to a Pd patch.
Instead you can just tweak the printing functions of the code and use the [serial_print] abstraction that I've made, especially for situations like this. You can find it here https://github.com/alexdrymonitis/Arduino_Pd
All you need to do is make sure you first print some sort of tag with Serial.print() (like "sensVal" for example), and the print the value with Serial.println(). Make sure you print a space in between the two. So you can do the following:

Serial.print("sensVal ");
Serial.println(sensVal);

In the example above the sensor values are being stored in a variable called sensVal. I first print the string "sensVal " (note the white space before the closing quote) and then I print the variable (no quotes this time) with Serial.println().
Then in Pd follow the example of the help patch of [serial_print] and use a [r sensVal] to receive the values.
This should do it.

Hey alexandros,

I've kinda been stuck with the same issue as the OP, and my aim is to not use the serial port abstraction but pduino itself for this task, since as far as I understand pduino uses comport itself to do the relays. Also with pduino, I can keep using firmata for all the other pins on arduino.
As you mentioned, the aim then is to translate the workings of the pulseIn() object into pd. I am trying to use the timer object to do so, but I'm wondering if I am missing something because as of now I seem to get a random output. Do you have any leads for this?

The thing with the ultra-sound sensor is that it has a trigger and an echo pin. The trigger pin is an output and the echo an input. You send a high voltage to the trigger pin and start counting time until you get a high signal from the echo pin (to be honest, this is an assumption I've made, but I'm pretty convinced that this is how it works). Then you should make some sort of equation to translate the time passed into distance. Probably you should read Arduino's source code and see what's going on in the pulseIn() function.