I have using four arduino uno in parallel with the Pduino library, using most of the digital and analog pins. As inputs. I have experienced many glitches with this setup and I have been OK with that since I am exploring and experimenting. But now I need to clean it up a bit.

What alternatives may there be instead of using arduino? Are there better solutions?

When using multiple arduinos, how to avoid problems?

Matrix switches... is this a good idea? To keep the arduino count low.

Thanks

I would avoid the Pduino library and write both the Pd patch and the arduino code if you are experiencing glitches. The problems might also be on the hardware side.
To read more than one button per input you can use a multiplexer.
Also you can buy a bigger board, the Arduino Mega has 54 digital pins...
Using more than one Arduino at the same time should be no problem, you can have multiple [comport] objects in your patch that read different devices.

That makes sense. It will be easier to add other code to the arduino as well if I skip the firmata.

Opps, multiplexer, that is what it is called. Is it good solution or will it add another layer of possible glitches? The switching frequently occurs at high speed, and many at the same time.

@cfry What OS? Be sure to run pd in realtime (using the -rt flag). Do you have glitches with the simple Test audio from the menu (without the arduino patch open)? It might be related to your audio buffer.

There is no glitches in the test audio signal. But I understand I need to turn off "use callbacks" in the audio settings. I use an audio buffer between 256 and 2048, depending on the complexity of the patch. I'm on Mac Osx High Sierra.
What does the -rt flag change?

@cfry Multiplexing is overkill for just plain old on/off switches, a diode matrix as is common in our synthesizer keyboards will get you you there with less headaches. You will have no problems getting all of your switches onto a single arduino which should greatly simplify both trouble shooting and maintenance. This looks like a pretty good write up on the switch matrix, only skimmed it but all the important bits seem to be there. https://learn.sparkfun.com/tutorials/button-pad-hookup-guide/background

You can also use shift registers for increasing the digital inputs (or outputs) of the Arduino. I've written a tutorial on the communication between the Arduino and Pd, you can find it here (it's called "Arduino for Pd'ers). The last chapter covers shift registers.

@alexandros I have started looking at your tutorial, figure I would benefit from doing it all the way through.

But I am using vanilla so how would I replace [repack]?

Great tutorial btw!

@cfry This vanilla abstraction..... bizarrely from the extended zexy library..... will do most of what the [repack] object does, and it might well be possible to get closer..... or maybe it will do what you want anyway?
repack.pd
David.

@cfry how are you using vanilla since you're using [comport]?

@alexandros

I do not use pd extended is what i meant by that, but I install externals if I really need them. Like [comport]. In your tutorial the pd examples use extended. The abs David posted above worked fine.

Yeah, it's true it's extended. It's an old tutorial. You can install zexy though and add it to your search path. It's a really useful library, perhaps indeed the "Swiss army knight for Pd" as it says.

@alexandros this is a bit OT but where can I find info on the zexy lib?

You can install it via deken and check its help patches.

@oid said:
...This looks like a pretty good write up on the switch matrix, only skimmed it but all the important bits seem to be there. https://learn.sparkfun.com/tutorials/button-pad-hookup-guide/background

I have completed @alexandros Arduino for Pd'ers now (except servo and multiplexing since I do not have the components needed). I feel it will be easier now when I do not have rely on Pduino. Although there are some parts I do not have full control of (read: hexadecimal handling) I think I can manage with some copy and paste-ing.

So now I need to set up a switch matrix a la midi keyboard. But the tutorial above is hard to adapt to my scenario. I have looked around but I can not find a guide that is more spot on. Any ideas?

I got the diodes but I need to understand how to make and connect the circuit to the arduino, make the arduino code, and then merge this code with the code for communication with Pd (the latter code is ready to go).

Thanks a lot folks

@cfry What makes it hard to adapt to your scenerio? Just add more rows and/or columns to suit, adding emitter followers or cmos buffers on the ins and outs would not hurt, but you may not need them, I do not know the specs of the arduinos or your number of switches so I can not say for certain.

Perhaps putting everything into pd terms would help? switchmatrix.pd

The one caveat is that I have no idea if the mcu (arduino) can send things as lists or if it is just a serial stream of floats, no difficult to deal with the stream if that is the case anyways. This should show you the logic of the switch matrix and the MCUs code and allow some experimentation, at the very least it should make our communication more efficient?

@cfry note that I have created two abstractions to simplify the communication between the Arduino and Pd. You can find them here. With these you don't need to do all the Pd patching plus you can use Arduino's Serial.print() function. Both abstractions are vanilla.

@alexandros could you give an arduino code example on how to use digital in and out at the same time?

@oid thanks for that pretty example patch. It made me really understand the whole concept and flow.

Since you went through my tutorial and got some code working, can you share what you already have? Then I can suggest changes to make it work with [serial_print].

@alexandros

Here is the working Arduino code, (which is basically a straight copy from "project 8", but I wrote it while reading the tutorial)

// setup for 6 analog in och 12 digital in (pullup to be added).
//intended as experimental template. use pd patch 
//made with tutorial Arduino for Pd'ers, project 8

byte myArray[25];

void setup()
{
  for(int i = 2; i < 14; i++)
  pinMode(i, INPUT);
  Serial.begin(9600);
}

void loop()
{
  myArray[0] = 0xc0;
  int index = 1;

  for(int i = 0; i < 6; i++){
    unsigned int knob = analogRead (i);
    myArray[index++] = knob & 0x007f;
    myArray[index++] = knob >> 7;
  }
  for(int i = 2; i < 14; i++)
  myArray[index++] = digitalRead(i);

  Serial.write(myArray, 25);
}

Then I tried to incorporate project 1 (blink):

// set a variable to hold the ledddddddz pin number
int led = 13;

void setup() 
{
//  st pin 13 as output, to light up the LED
// whenever it is told so from Pd
pinMode(led, OUTPUT);
// start the serial communication o the Arduino
// and Pd can communicate with each other
Serial.begin(9600);
}

void loop() 
{
 while(Serial.available()){
  byte ledState = Serial.read() - '0';
  digitalWrite(led, ledState);
 }
}

but when I tried to edit "blink" to work with several outputs and merge this in the project 8 code, I decided that I do not have enough understanding of the arduino code to pull it through. What is needed is, I think, another "for()" combined with digitalWrite() inside void loop()

Note: My plan now is to (still) use several Arduinos but with your code and abstractions (instead of the Pdunio). I will wait with the matrix switch setup since I have to take this in steps in order to have control of it.
This means that I am up and running, unless I want to use digital input and output from the same Arduino at the same time. I figure it would be great to have that sorted out beforehand so it works when I need it.

Thanks a lot.