🚀 go-pugleaf

On 24 Mar 2002 22:13:10 -0800, robert@wavemechanics.com (robert
bristow-johnson) wrote:

>Al Clark <dsp@danvillesignal.com> wrote in message news:<Xns91DB81B2F6D2aclarkdanvillesignal@209.249.90.101>...
>> john_wr100@yahoo.com (Johnny) wrote in news:3c9db1ea.6888487
>> @news.optusnet.com.au:
>> 
>> > On Sun, 24 Mar 2002 10:18:32 GMT, john_wr100@yahoo.com (Johnny) wrote:
>> > 
>> > I am planning on doing some experimentation with digital fitlers. I
>> > want to make an active crossover for my audio system. I was looking at
>> > one of the following kits:
>> > 
>> > Motorola DSP5636X Evaluation module.
>> > or
>> > Analog devices ADSP-21065L Ez-Kit lite
>> > 
>> > I probably need about 80 Million multiply/accumate per second and at
>> > least 24bit fixed point. Faster is better though.
>> > 
>> > I dont mind programming in Assembly or C language.  I figure that
>> > assembly is probably fine because my code should be pretty simple just
>> > to implement FIR filters and  I/O functions.  I was kind of scared by
>> > roughly 1000 pages of documentation for the motorola development
>> > system and DSP programmers guide. 
>
>wow.  not having an EVM since the 56002, i didn't know they sent any
>documentation (other than the "Family Manual", and a text-only manual
>for the assembler) with the kit.  despite some of the warts in the
>563xx generation (the children are more sophisticated, but not quite
>as pure of heart as the parent), i still think that when the smoke and
>dust clear, the Mot arch and asm is simpler to deal with than the
>SHArC.  i still am skeptical about the need for floating-point for
>most audio, but if you find you need floating-point, then your
>decision is much more clear.
>


>in either case, i would perform any FIR kernals in fixed-point.

Yes..  It seems like the Motorola is well suited to FIR audio filters
with 24bit fixed point maths and 56bit accumulator.  (IIRC)

I also Think that 24bit is plenty good enough for audio.  But 32bit
bit floating point is a lot like 24bit fixed point with an 8-bit
exponent term.  Not sure how bit the SHARC accumulator is, but I  will
check it out..The SHARC processors are a lot faster than the Motorola
56300 series.  So its not a problem for me that they do 32bit maths
insted of 24bit.

The problem I normally have with Motorola processors is that they
normally have 3rd party development tools which are far too expensive
for the hobbiest.  Based on past experience with Motorola embedded
processors, the Evaluation boards are normally also super pricey.  To
be honest, i have been too scared to even call the local Motorola
distributer as they don't have a reputation for good pricing either.
Maybe the 56000 dsps are an exception to the Motorola norm and worth
checking out.

best regards,
John.