uC Wars part 237534 - was:Re: [sdiy] super cheap synthisizers

Theo t.hogers at home.nl
Wed Jun 12 06:55:42 CEST 2002

If your plan to program in assembly it might be wise to consider Atmel AVR
instead of PIC.
You will find there are cheap 'n easy to build programmers around,
lots of examples available and free development software from Atmel.

AVR are slightly faster,
there is no memory page shit like with the PIC,
code size is smaller and
best of all there are 32! registers vs 2 on the PIC.
Some instruction only work on the first 16 registers,
but still lot o' registers makes efficient assembly coding much easier.
Don't store a value from accu to stack, just use an other register as accu
Frequently needed variables can have their own register :))

If you do the C thing, the PIC and AVR do about the same.
C doesn't take advantage of the register wealth on the AVR :(

Just a thought,
Grown up with TMS9900's 32k worth of 16 bit registers
(yes that was the complete RAM, no difference between RAM and registers)

From: Dominic Tarr <dmt10 at waikato.ac.nz>

> wow, you guys are fast.
> yeah, I was planning to use PIC chips cos they are easily avialable, and
I've found lots of documentation on how to program them, and I can easily
build a programmer. I was planning on counting the clock cycles, and only
having a pulse out put, a saw would be nice, but I can live with out it.
especially if I can  have 2 pulses.
> midi control of course, cos otherwise you would still need a midi to CV
converter, and that doesn't sound "super cheap"
> there would be lots of ways around not having enough resolution in
"sample" time, like making the first period slightly higher and the next one
slighty shorter, so it works out even. I'd imagen that this would probably
sound quite interesting too. <<< also as I expect to be using it mainly for
bass so I don't think having only 20 steps to have a 4kHz note is much of an
> I guess I'm a bit of a newbie though, so please bear with me...
> does any one have some really simple designs for VCFs and VCAs lieing
> really it's the analog side of things I'm not sure about, like what would
I need to do to bring the ttl level out puts up to line level (or what ever)
for feeding it into filters?
> cheers - Dom

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