uC advice

[Byron G. Jacquot]

>Can any list members give me some advice on getting started?  I know that some 
>synth-diy people have used the Atmel micros, as well as the PICs.  My main 
>application right now would be generating several CVs and gates, possibly in a 
>polysynth or multi-voice design.  Also, can any of these uCs be programmed
with 
>a Mac, or am I looking at having to get an old PC?  (I have a PowerPC Mac as 
>well as a new G3). 

Several of us on the list are partial to the Atmel micros.  You can get into
their AVR range with a $50 eval board, with headers that can be tied to
anything you care for IO.

They're a fairly serious processor for an 8-bitter.  They are a 32 register
RISC design, and about 1/2 of the instruction set takes only 1 cycle per
instruction.  They run easily at 8 MHz, some variants go up to 12 MHz.  They
offer a lot of on-board peripherals, as well.  RAM, Flash ROM, EEPROM, UART,
SPI, timers, and some analog connectivity (comparitors and ADCs).

Actually, just about every small processor out there these days comes with
those sorts of periphs.  Anything with a UART will probably handle MIDI to
some degree.

There are a reasonable range of free tools available (assemblers, a somewhat
buggy emulator) for the AVR, also.  The HLLs (C, BASIC, FORTH, JAVA maybe?)
range from free to professionally expensive.

Also, if you're looking into doing MIDI conversion, a little bit of math
tells you that you dont need much of a processor.  A single byte of MIDI
data takes .00032 seconds (that's 10 bits at 31,250 bits per second) to be
sent.  An 8MHz processor would execute 2560 instructions in the time that
byte takes!  You can probably do most MIDI tasks, including polyphonic voice
mapping in a few dozen of those cycles.  So it doesn't take a screaming
processor to handle MIDI data.  If you think you'll be more comfortable with
a Motorola 68XX, (05, 09, 11, 02 etc), they shouldn't be too overburdened,
either.  But I dont think the tools are as affordable as the AVR's.

I can't comment on the mac thing, but you might be able to run the software
in a windows emulation (correct me if I'm wrong) mode.  If it can see the
parallel port, it'll probably be OK.

Byron