Hey,

I've been struggling with puredata on a raspberry Pi4 all day. After finally managing to install comport, I'm running into an issue outputting to my arduino.
I'm trying to send a 6 figure string to the comport (opened on port 1, serial rate 9600), but I'm getting the error:
"Write failed for 0 bytes, error is 2"
I'm not really sure why this is happening - I ran an identical patch in Max that worked without issue but this doesn't seem to work. I'm assuming that there is an issue with the way the data is formatted but I don't exactly know what the issue is.

Thanks!

Can you share your patch, and the Arduino code?

Hey, sorry, was posting on my mac, here's the patch from the pi:

The weird thing is that if I run comport in the help files, I can send data directly as:
[int]->{% 255]->[comport 1 9600], but if I do the same thing in my patch it doesn't work

The arduino code is:

#include <FastLED.h>
#define LED_PIN     7
#define LED_PIN2    6
#define LED_PIN3    5
#define LED_PIN4    4
#define LED_PIN5    3
#define NUM_LEDS    1
CRGB leds[NUM_LEDS];
CRGB leds2[NUM_LEDS];
CRGB leds3[NUM_LEDS];
CRGB leds4[NUM_LEDS];
CRGB leds5[NUM_LEDS];
int incoming[5] = {0, 0, 0, 0, 0};



void setup() {
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN2, GRB>(leds2, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN3, GRB>(leds, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN4, GRB>(leds2, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN5, GRB>(leds, NUM_LEDS);

  Serial.begin(9600);


}
void loop() {
  if (Serial.available() > 0) {
    // read the incoming byte:
  }
  incoming [0] = Serial.read();
  incoming [1] = Serial.read();
  incoming [2] = Serial.read();
  incoming [3] = Serial.read();
  incoming [4] = Serial.read();
  leds[0] = CRGB(incoming [0], incoming [0], incoming [0]);
  FastLED.show(); 
  leds2[0] = CRGB(incoming [1], incoming [1], incoming [1]);
  FastLED.show(); 
  leds3[0] = CRGB(incoming [2], incoming [2], incoming [2]);
  FastLED.show(); 
  leds4[0] = CRGB(incoming [3], incoming [3], incoming [3]);
  FastLED.show(); 
  leds5[0] = CRGB(incoming [4], incoming [4], incoming [4]);
  FastLED.show(); 
}```

Which works using the following max patch: 
![Screenshot 2021-12-16 at 21.18.20.png](/uploads/files/1639685913315-screenshot-2021-12-16-at-21.18.20.png)

Which works using the following max patch:

@Doomspeak

There's at least one key error in the pd window.

"pack: i: bad type"

Max has ints, Pd doesn't. Every number is a float. You'll need [pack f f f f f]. You're probably getting an invalid list out of that.

The Max patch produces a list of 5 numbers; the Pd patch, 6. I guess that is not intentional. Probably you want to ignore route's rightmost outlet.

Also the Pd patch is missing the 1 -> 255 logic.

hjh

Ok, I'll try this.
Still, if I just send a test message with a string like
[1 1 255 255 1 ] -> [comport]
it should light two of them, but when I send that I still get the error, which made me think something else is going wrong.

(the 5 vs 6 values is just my brain melting, thanks for the float tip, it's something I noticed but hadn't internalised yet)

@Doomspeak Your Pd patch is not identical to the Max patch I think.
The Max patch has a [metro] repeatedly banging the list into comport.
I don't know python but maybe the {loop} is expecting new data at least every 100ms?
Maybe the 255 gets through but is simply reset to zero on the next cycle?
I am probably wrong about that........ but try this patch........ test.pd
David.

Why are you reading the bytes from the serial buffer outside the if (Serial.available() > 0) test? Nothing is happening inside those curly brackets. All Serial.read() should happen within those curly brackets. Though, I guess the bytes will be available after the empty code snippet. Also, in the Pd patch you're using a fan out connection. Use [t b f] connected to every outlet of [route] that connects to a cold inlet of [pack].
As @ddw_music correctly pointed out, there's no [pack i i i i i]. What you need to do is change it to [pack f f f f f] but make sure you pass those values through an [i ] object before sending them to [pack].
Lastly, a better version of the code that reads the serial buffer is this:

int index = 0;
while (Serial.available()) {
  incoming[index] = Serial.read();
  index++;
  if (index > 4) index = 0;
}

Or something along these lines.

Thanks for that. This still doesn't help the error I am receiving though - I still cannot send a basic string into the code - the code does work if I am doing it in Max. Do you have an example of how comport ought to be set up to output a string of 5 numbers?

Maybe it has to do with the frequency you're sending the data. In the Max patch. [serial] is being polled every 100ms. Perhaps you have to reduce the frequency of your data. Other than that, [comport] can accept lists of values the way you do it, and these should be readable by the Arduino code.