[sdiy] I2C DAC

[Mike Beauchamp]

I don't mean to jump in on this thread, but can anyone show me an
example of a 12-bit DAC  (I2C is fine) that is being used to output
CV?

I guess I was always under the impression that DAC chips were only
useful for audio applications (that is, constantly changing values)
and I never thought they could actually just "hold" a value and do it
with any stability, etc.

Mike




On Sun, Jun 20, 2010 at 9:28 AM, Eric Brombaugh <ebrombaugh1 at cox.net> wrote:
> On 06/19/2010 02:09 PM, MTG wrote:
>>
>> I'm almost out of pins, but I have two left in a project that I want to
>> hook a DAC up to for control voltages. Anyone recommend a decent I2C
>> single or multi-channel 0 to 5v voltage out DAC? What are most people
>> using for resolution of control voltages these days? I know 7-bits was
>> the standard for a long time. Is it worthwhile looking at higher
>> resolution for things like filter cutoff or pitch bend or ... ?
>
> I think you'll have a hard time finding something as low as 7-bits
> resolution. 8 is pretty common, but for CVs is a bit coarse. 12-bit
> resolution will cover most CV applications without too much in the way of
> zipper effects and can even be used for reasonably accurate 1V/Oct scaling.
>
> What processor are you using? Does it have a hardware I2C capability, or
> will you have to bit-bang the low-level protocol? I2C can be a bit tricky
> due to the built-in acknowledge cycle, and somewhat slow to update due to
> the relatively low clock rates. On some MCUs the pins available for I2C
> ports are limited due to the open-collector drivers required so you may not
> be able to arbitrarily reassign them.
>
> Eric
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