Fwd: urgent question about Motorola 56F8323, signals, DSPcore, time

---------- Forwarded message ----------
From: Sik
Date: 03/06/2006 10:34
Subject: Re: [motoroladsp] urgent question about Motorola 56F8323,
signals, DSPcore, time
To: b...@rogers.com
When I wrote the first mail, I was using it as a uController. I didn't
use any kind of DSP or low level instructions. Now I try to use MAC
instructions (which are like MPY + accumulation of D register).
However I'm a little confused: what did the registers contain before
the execution of the instruction (Do I need to save their state?)?
what exactly mean a 'fractional value'?
2006/6/3, b...@rogers.com :
>
> Are you using MPY, parallel dual reads?
>
> ----- Original Message -----
> From: Sik
> To: m...
> Sent: Friday, June 02, 2006 4:01 AM
> Subject: [motoroladsp] urgent question about Motorola 56F8323, signals,
> DSPcore, time
>
> Hello, all.
>
> My goal is to use 56F8323 Motorola's Hybrid Controller for filtering a
> sinusoidal signal sampled up to 96 KHz with a bandpass.
>
> To implement the digital filter I've to multiply 4 float values and
> (add/subtract) the results, between every sample.
>
> At this moment I use the uController to get the signal from the integrated
> ADc and reproduce the sample through a SPI DAc, all at 48Khz (to not be
> ambitious). For test the performance I add between acquisition and
> reproduction a stupid code that multiply and add some values.
> The code's:
> aux=aux+aux; aux=aux*aux; aux=aux*aux; aux=aux*aux;
>
> The compiler translate every instruction to 3 'move.l' and a 'jsr' asm
> instructions, who spend 18uS on 56F8323@60Mhz (Which's a lot of time because
> the period@48Khz is just 20uS long).
>
> Somebody can show me the way to use the 56F8300E core to be able to
> calculate the 4 multiplications and the 3 adding float operations within
> less than 20uS(48K) or 10uS(96K) ?
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