AW: PIC power?

Mikko Helin helin at uta.fi
Sat Nov 20 12:48:01 CET 1999


On Fri, 19 Nov 1999, Paul Maddox wrote:

First, I've nothing against using AVR's, in fact I'm going
to use them instead of PIC. I agree (after writing a keyboard
scanner code for PIC) that it's quite limited. What I tried to
say is that 486 system would be easier to adapt to than AVR.
As Baron noticed, the used motherboards with 486's cost
next to nothing. Yeah, 486 is for computers, AVR is a microcontroller
for specific purpose.

> 
>   Ive started using the AVR for my projects (check out my
> 4 channel Midi>CV convertor on my webpage) it was pretty
> is get going, it doesnt have bulky over heads that an intel 
> does, like ram/rom/hdd/screen/keyboard/mouse/bus controller/etc/etc.
> It takes virtually no power (5V at 3mA running at 8Mhz).

Yes, and they are much more reliable when used on gigs.
> 
>   Agreed its not 32 bit, but hang on, midi is only 7 bit (for most
> stuff such as controllers and note).

With AVR you can do 32 bit arithmetics if needed, if fact with
the Mega AVR's (161) with multiply instructions you could program
one voice synth (DCO+DCF+DCA) easily.

> 
>   Ive decided to take up someones comment about a DDL
> and Ive ordered some sample ADC/DAC (serial) from Analog
> Devices and I reckon I could make a DDL with CV  control
> of delay time without any hassle, I plan on using 16Bit serial
> ADC/DAC's, these run at 2Msps, which is MORE than enough
> for audio DDL, so 16 bit IS possible without any problem.
> 

Hey, I have an idea for parallel/serial conversion. As the
AT90S1200's are pretty inexpensive you could program one
to do say 16 bit (or 2x8 bit to save space and pins) parallel 
to I2S (or SPI) conversion (or the other way). They clock nicely at 
12 MHz, which is also a good frequency ( for ~ 46 kHz sample rate)
to be used as master clock for deltasigma converters.
So a 8515 could be used as main controller for the thing,
and timed with external signal from 1200 at sample rate
(or 2xFs if an 8 bit port is used to transfer data between the two)
used to trigger an INT on 8515. With AtMega161 then it would be
possible to program the VCO, and the VCF using the code from
Hal Chamberlin's book for the digital state-variable filter,
which needs just two multiplications (4 on AVR) / sample.
AVR can also read program memory so you could put some
wavetables there.

>   Mikko, sorry if this sounds like a dig at you, its not. I just happen
> to feel very passionate about the AVR range and theres not enough
> sites out there that a relivant to AVR's and Music (Ive only ever
> found 2, and now mines there so that makes 3).

I'm sure going to use them also, though I don't know yet when,
but I also would like to have standalone MIDI CV converter
with 8 CV outputs, LFO's and EG's. I guess I'll do that
with AVR and use MIDI control for setting the parameters,
and later build a MIDI controller thing with pots etc.

-Mikko





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