[sdiy] "lunetta"/CMOS sound-making equivalents in C Programming???

[Dan Snazelle]

Thanks for the info!

Sent from my iPhone

On Mar 22, 2012, at 1:04 PM, nvawter at media.mit.edu wrote:

> 
> Heya Dan!
> 
> I noticed you were on an electromusic thread about 4522s and 4015s my friend sent me this morning.
> 
> uControllers can do lots of similar stuff to CMOS logic, with certain limitations (and certain advantages!)...  One of my favorite resources for this is believe-it-or-not, the wikipedia page on LFSRs!  It shows the "slow" (Fibonacci) and "fast" (Galois) way to make a shift register with feedback in C.
> 
> Typically, you'll want to have a loop running and shifting a register every clock cycle.  It's safe to use a nice wide variable like an unsigned 32-bit word.
> 
> A divide-by-two could be implemented as:
> while(1){
>  if( 0x1 == ((prev_div_in<<1)|(div_in))   ){div_out^=1;}
>  prev_div_in=div_in;
> }
> 
> that detects a transition from 0 to 1.  On that transition, it inverts the output.
> 
> I'm messing with this stuff, too, but aiming to place it inside a cheap CPLD to save space.  Someone (this list?) showed me the Amani CPLD board with the AlteraEPMx064 on it.  Those (reprogrammable, socketed PLCC) chips cost $2.10 in single quantity!  and they can take the place of a dozen CMOS chips!  Of course you have to learn a clumsy HDL language (and they are wonky, amiriteladies?), but it's not that hard, mostly C-like logic symbols.  And the CPLDs can potentially run much faster than the CMOS logic equivalents, too!  And there's a simulator (not with audio though, sadly!)
> 
> 
> 
> 
> 
> Quoting dan snazelle <subjectivity at hotmail.com>:
> 
>> Often I use counters, Logic, clocks, R2R's , shift registers and flip-flops to make sequencers, CV generators, cheap crazy sounds,etc.
>> 
>> 
>> I was wondering what is possible using a micro-controller and C to replicate or expand on some of those techniques to end up with a vocabulary of fun and quick
>> noisemakers.
>> 
>> 
>> for example, a common use for CMOS in sound making is taking a clock, putting it through a  4040 counter (12 bit) or similar, taking the taps, ANDING them with other clocks,
>> XORing the result, etc.
>> 
>> 
>> So...
>> 
>> 1. How can you replicate something like a 4024/4040 in a program (  a counter with multiple outputs/taps                                                                                                                                                                                                                  ?
>> 
>> i think a for loop is a counter, would i just set up a bunch of if statements ?
>> 
>> for (i=0; i<12; i++)
>> 
>> if (i=2)
>> dacTap1=HIGH;
>> 
>> 
>> 2.  how can i make a simple divide by 2 in code?
>> 
>> 
>> 3. what about replicating shift registers?
>> 
>> 
>> thanks for ANY IDEAS!!
>> 
>> 
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> 
> 
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