endworkproject: midi2cv

[Mikko Helin]

On Wed, 27 Oct 1999, Das Roel wrote:

> I finally got to discussing my endwork project with my promotor. I have to concentrate on the midi-cv convertor. 
> It should be at least as good as the commercial models, or have more options, possibilities... 
> What can you put in these things nobody has ever thought of? An arpegiator would be nice for example... 
> Give me all the hints you can, i need inspiration!
> 

OK, I've revised the MIDI CV generator specs a little ( see
http://www.uta.fi/~helin/midicv.pdf what I've been planning).

AVR (STK200, 8515) starts look better alternative to PIC 16F877, though
the latter is still ok for smaller projects. The differences are small,
like the lack of ADD with carry opcode in PICs, but you will need such
operation to be able to implement decent 16-bit envelope generators 
(8 bits is not enough).

Also I think the best platform for MIDI CV generator/converter would be an
old PC. The used 486 stuff is now inexpensive (like I could get 20 pieces
of 468 motherboards with 486SX-33, VLB I/O and VLB SVGA controllers for 10
EUR /piece or 85 EUR/10 pieces). Problem is the analog i/o, you may want
to use the parallel port interface, though building an ISA card is not too
difficult and would be better solution.

> And a question on the commercial models. Most of them have got 
> LFO's built in. Are these LFO's wavetable-based? Are they 
> controllable by midi in any way? 
> This also inspired me, would a build in DCO be handy? 
> For example to easily connect a wavetable-reader?  

Why not, check the Atmel site, they have an application note for wave file
player. As the AT90S1200 series chips are so inexpensive you could easily
build multiple DCO's around them. However, it's better not to put the DCO
into MIDI CV controller but have it on separate chip(s). The LFO and EG
though are OK (they are slower and won't need so much cpu time).

-Mikko

> Thanks
> Roel
> 
>