AM's digital/analog polysynth project

[AndrewMartens]

Well, I've been busy this past while:  switched jobs to something better (hooray!), still contracting with my old company (=$ to buy test equipment, but then I have no life), and other unhappy things.

There's a bright side, though!  In my spare time I've been thinking about some of the algorithm problems I was having with the design of the DPS, and I believe most of them are sorted out:  envelopes, mixing, interrupts, communication stream, etc..  I'm quite confident that I can get an SPI-controlled quad-oscillator multi-waveform synth working.  With luck I'll be able to do one volume envelope per oscillator (=4), two LFOs, and a final DCA with its own envelope.  Assuming I can get all *that* working, then I'm going to go back and look at doing some kind of digital filter.

Oh, and I'm probably going to just go with an 8-12 bit resistor ladder (R2R) output - if I'm doing an internal DCA then there isn't much point of wasting board space and money with an external DAC.  I've also been toying around with the idea of being able to slave up to 16 units off the same SPI bus and being able to either uniquely address each one, or broadcast the same settings to all of them (ie, to load up the same patch for all 16 units).  Not sure why anyone would want to do it, but it should be possible. 

I'm getting to the point when it's time to start consolidating the bits of code and run some simulations in MPLAB.  Then it will be "build a prototype" time, and then I should be able to make some noise with this thing.

[cheater]

Well, I've been busy this past while:  switched jobs to something better (hooray!), still contracting with my old company (=$ to buy test equipment, but then I have no life), and other unhappy things.

:(

There's a bright side, though!  In my spare time I've been thinking about some of the algorithm problems I was having with the design of the DPS, and I believe most of them are sorted out:  envelopes, mixing, interrupts, communication stream, etc..  I'm quite confident that I can get an SPI-controlled quad-oscillator multi-waveform synth working.  With luck I'll be able to do one volume envelope per oscillator (=4), two LFOs, and a final DCA with its own envelope.  Assuming I can get all *that* working, then I'm going to go back and look at doing some kind of digital filter.

great! :)

Oh, and I'm probably going to just go with an 8-12 bit resistor ladder (R2R) output - if I'm doing an internal DCA then there isn't much point of wasting board space and money with an external DAC. 

Humm... don't go down the route of style over substance... it's easy to get lost in that!

I've also been toying around with the idea of being able to slave up to 16 units off the same SPI bus and being able to either uniquely address each one, or broadcast the same settings to all of them (ie, to load up the same patch for all 16 units).  Not sure why anyone would want to do it, but it should be possible. 

Multitimbrality? :)

I'm getting to the point when it's time to start consolidating the bits of code and run some simulations in MPLAB.  Then it will be "build a prototype" time, and then I should be able to make some noise with this thing.

Looking forward to that!

cheers :D

Damian