[PD] PD to CV redux (Arduino)

[Christian Klippel]

hi derek,

Am Mittwoch, 11. Oktober 2006 19:35 schrieb derek holzer:
> I wanted to bring this super interesting discussion back, since it only
> touched on a few different things before wandering off into ModTracker
> territory (not so interesting for me...)
>
> If I wanted to program an Arduino to send out Control Voltage for a
> modular synth, what would the resolution be? Would it be better than
> MIDI? Enough for microtones? Could it make quick modulations? (I saw
> that the filtered PWM method which some mentioned here is not good for
> fast changes in voltage.) How many channels could I get out of one
> board? I have two, but I haven't touched them yet. Would I need extra
> hardware (filters etc) to modify the voltage before it goes to the
> synth? Would anyone be interested in helping with such a project? In the
> Berlin area even? Are there any programs written for the Arduino that do
> this already?
>

a really fast way is to use an external dac chip. for example something like 
http://focus.ti.com/docs/prod/folders/print/dac7614.html

there are lots of different one, just choose the number of channels and 
resolution, and take care that it comes in a package that you can solder. 
pdip are the big standard packages, soic is smd, but still easy to work with:
http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?startIdx=1&endIdx=10&familyId=392&uiTemplateId=NODE_STRY_PGE_T&sectionId=null&tabId=null&appId=null&viewDeviceCallingPage=null&totalCount=147&showAdditionalParameters=no&lc=2000084&lc=2000112&lc=2000596&lc=2300989&lc=2000116&lc=2000376&lc=2000089&compare=yes&download=yes&sort=yes&customize=yes&paramResults=yes&paramCriteria=yes&familyTree=yes&military=no&baSystem=yes&paramTable=no&sortOption=&sortMode=&searchPaths=1000392&pageId=undefined&startIdx=1&endIdx=10&templateId=0&navigationId=0&family=analog&paramTable=no&military=no&ul=DAC7554&ul=DAC7558&ul=DAC7571&ul=DAC7573&ul=DAC7574&ul=DAC7611&ul=DAC7612&ul=DAC7613&ul=DAC7614&ul=DAC7615&&uiTemplateId=NODE_STRY_PGE_T&sectionId=null&tabId=null&appId=null&viewDeviceCallingPage=null#rt

hint: you can get samples from ti. click the "samples" link at the top of each 
product page and choose the one you want from the list. you need to register 
first.

with such an dac you get real voltage output that doesnt need to be filtered 
for your application. altough most dac's are serial, the communication is 
very fast and often allows up to audio sample rates or more.
implementing the code to write the dac is fairly simple, since it usually is a 
standard i2c or spi interface. its also well explained in the datasheets.

> best,
> d.

greets,

chris