Ardcore additional analog outputs?

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scottwilson
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Ardcore additional analog outputs?

Post by scottwilson » Wed Sep 25, 2013 7:46 pm

For those who may know, is it possible to use any of the analog inputs as outputs? I know the Arduino supports it, but I'm guessing the circuit board is set up in such a way that they will only work in input mode?

Thanks,

Scott

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scottwilson
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Post by scottwilson » Thu Sep 26, 2013 4:19 pm

So doing a little more research I understand a little better now.

The Uno has no analog outputs... The Ardcore uses 8 of the digital outs to add up to 8 bits worth of CV...

The only pins that are multi-purpose between input and output are the digital pins. I was getting confused because you can call analogWrite() on a digital pin that is PWM capable.

Doing some thinking, the Ardcore - which is great, mind you - is a tad limiting in the grand scheme of the arduino world. It could also be that as someone who's a little more interested in droney noises, I prefer CV to trigger outs.

I've purchased a Due and a couple of I2C 8 Channel 10bit dacs. This will give me 16ch of 0-5 volt outputs! We'll see. maybe, but that would be nice.

Anyway, some thoughts. I'm getting my C++ skillz in order and working on some algorithms. We'll see about that too!

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fac
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Post by fac » Fri Sep 27, 2013 12:00 pm

It can be done with some work and one or two slew limiters. When you run a high-frequency pulse signal through an integrator (such as a slew limiter), the output of the integrator (slew limiter) will be proportional to the pulse width. Therefore, you can control the output voltage by controlling the pulse width of any digital output.

Output D0 directly supports PWM (by means of the analogWrite() function), so you can use it as a non-precision, low-frequency analog output by running it through a slew limiter. It won't be good enough for audio, but it's good enough for LFOs and envelopes. I have a a triple-LFO patch and a quadrature LFO patch which uses D0 to output a second LFO.

With some work, you could probably implement PWM in D1 as well using clock interrupts.

That's why my YuSynth Dual Slew is my Ardcore's best friend. It allows me to implement 3 separate analog outputs.

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scottwilson
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Post by scottwilson » Fri Sep 27, 2013 12:39 pm

Nice. Thanks for the pointers.

loss1234
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Post by loss1234 » Wed Oct 02, 2013 1:05 am

yes you can use do and d1 as outs

plus the expander adds 10 outs

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