uC advice

[KA4HJH]

>However, from what I understand, the 68705 is not really
>suited to larger applications, e.g. generating lots of CVs and gates.  I know
>that there are other uCs out there that are more user-friendly, some of which
>can even be programmed in high-level languages, have all sorts of A/D, etc.

The 68075 has been supplanted by the HC05 series, of which there are 
many version. Although still a Motorola fan, I'm dismayed by the lack 
of inexpensive development tools for this processor. There's one 
relatively cheap board available and that's it as far as I know.

Moving up a notch are the HC11 and the HC12. The former has been 
around a while and there are lots of inexpensive boards, etc. 
available. It's significantly more powerful than the HC05's. It's my 
personal favorite. The HC12 is newer, more powerful, and the price is 
dropping.

The Atmel AVR has lots of horsepower and is also extremely popular. 
It's an improved version of the Intel 8051.

The name looming over everything these days is PIC. Sheer volume has 
made it the most talked about. And the hottest thing right now is the 
16F8x. With flash RAM, in-circuit programming and 5 MIPS it's quite a 
bargain for $6.

All of these families of processors have been used for MIDI and I've 
seen the software around. The PAiA midi2cv8 gets by with a venerable 
old Z-80. As for generating CV's, that's pretty straightforward until 
you start implenting your own LFO's and envelope generators in 
software. Not only does this require much higher sampling rates (1kHz 
is plenty for pitch voltages) but the resolution pretty much has to 
be increased to 12 bits or more, otherwise you get the dreaded zipper 
effect. For that you'd need a fast processor that can handle 16 bit 
numbers easily (an HC12 perhaps?)

>Also, can any of these uCs be programmed with
>a Mac, or am I looking at having to get an old PC?

Most inexpensive/cheap programmers use the PC's parallel port. While 
you can rig up a parallel port on a Mac, all of the software is 
written for guess who. There are serial programmers, however. You can 
get an old PC for nothing these days but you lose a certain amount of 
convenience, to say the least. There's a full-blown serial PIC 
programmer for around $89, and Mac software to drive it (I told you 
they were popular). The HC11/12 are virtually always serial and often 
have a monitor in ROM.

Mac AVR programming:

http://wollongong.apana.org.au/~ben/macavrpa/macavrpa.html

MacPIC software:

http://www.srv.net/~kxc/MacPIC.html

serial PIC programmer:

http://www.new-elect.com/


I could go on but I'm too tired.

>(I have a PowerPC Mac as well as a new G3).

The G3 is a PowerPC.  8)

Terry Bowman, KA4HJH
"The Mac Doctor"

ICQ: 45652354