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[dsp] AFSK demodulator code for ARM7TDMI?

scott at opentrac.org scott at opentrac.org
Fri Feb 11 15:30:30 UTC 2005

I looked at the AVR chips myself and decided I didn't really like the
architecture.  Guess it's just that I grew up with von Neumann architecture
chips.  So I'm using an Atmel chip, but one of their Smart ARM series - the
AT91SAM7S64, which has an ARM7TDMI core.  It does about 50 MIPS and has a
MAC instruction - though I don't recall the details at the moment.  It's a
32-bit chip with 64k Flash and 16k RAM, and it's set up like an 8-bit MCU,
with a single supply, relatively simple clocking, and lots of on-chip
peripherals.  Runs about $6.50 in small quantities from Digi-Key.  For about
$12, you can get it with 256k Flash and 64k RAM.

It's also got a full-speed USB interface (which has been keeping me busy
with driver debugging), SSI for CODEC interface, 10-bit ADCs, SPI, USARTs,
PWM, and so on.  I haven't actually got it set up yet, but apparently the
peripheral data controller can interface with the USARTs, SPI, and SSI, and
handle flow control and transfers to/from memory buffers with no processor
intervention.  That's something I haven't seen on the 8-bit chips I've been
using.  So far I'm really happy with it.  The starter kit, with eval board
(I've since added an SD/MMC socket to it), USB JTAG interface, and C
compiler (32k code limit) sells for $300.


-----Original Message-----
From: dsp-bounces at lists.tapr.org [mailto:dsp-bounces at lists.tapr.org]On
Behalf Of Mark Jordan
Sent: Friday, February 11, 2005 3:39 AM
To: dsp at lists.tapr.org
Subject: Re: [dsp] AFSK demodulator code for ARM7TDMI?

	The AVR family has a TWO clock cycle instruction that does
8x8bit multiplication. And a 16MHz AVR can do 16 MIPS!
	Signed 16bit multiplication can be done in 20 clock cycles.
	It is amazing what can be done with the AVR processors.

	Mark Jordan - PY3SS

On 11 Feb 2005 at 1:34, David Willmore wrote:

> > 	Hi Scott,
> >
> > 	I wrote that code for a client so I guess I shouldn't make
> > it available, sorry. But I can help you write your own code.
> > 	The fixed point 16-bit math routines I used are available
> > from Atmel. No need for floating point.
> >
> > 	Mark Jordan
> > 	PY3SS
> Mark,
> I'd be interested in looking at some of this, too.  I'm currently
> doing some DSP on PICs and will probably be moving to dsPICs before
> long.  I'm finding it surprising how much work can be done with
> such a small chip. :)
> Cheers,
> David n0ymv

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