[Pd] Serial port out

[Cesare Marilungo]

Hans-Christoph Steiner wrote:

>
> On Nov 6, 2006, at 6:42 PM, Martin Peach wrote:
>
>> Chuckk Hubbard wrote:
>>
>>> I'm going forward with this Moog-controlling plan.
>>> I have Pd on my laptop, and have compiled [comport].  I'm not sure  how
>>> to use it, though.  As with so many things, most of the info I can
>>> find online tells me way more than what I want.
>>>
>>> What I want:
>>> Is it possible to send constant values OR individual bits to the
>>> serial port, as opposed to bytes separated by on/off bits?  How can I
>>> set up the timing on this to send controllable PWM?
>>> Will it be possible to send PWM from comport with -noaudio?
>>
>> You can toggle the handshaking lines at high speed but you will run  
>> into the jitter caused by pd's audio block size. Or you could send  
>> data through the serial port with different ratios of on and off  
>> bits, but you will only get 8 different levels. I think you need to  
>> put a serial dac there. It's possible to clock serial data into a  
>> dac using just the handshaking lines -- one serves as a clock and  
>> the other data.
>>
>
> That's an idea for an object written in pd [serial-pwm].  It would  
> PWM signals by flipping bits on the serial port.  Frequency would be  
> determined by a combo of baud rate and bits used for one cycle.
>
> Hmm, I wonder if it would be useful at all...
>
> .hc
>
I'm not an expert in electronics. But I believe that this should need a 
microcontroller.

You send the notes you want to play via serial port to the 
microcontroller, which sends a pwm signal that can be flattened with a 
simple rc circuit (a condenser and a resistor).

I've done this some years ago to control my Korg MS20. I've used an IC 
(Max232, IIRC) and the PIC 16f84a. It costed less than 5 EURO in parts.

There are plenty of ready made projects and schematics for this task 
(just google for it).

Ciao,

c.

>
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