> From: Henrik Lewander <icebyte@as-if.com>
> Hello all.
>
> We are thinking of building a simple audio-spectrum-analyzer.
> The output would consist of a LED-matrix (7 bars, 8 LEDs / bar).
>
> Is this possible with the C84 (or F84 :) and an A/D-conv + FFT in
> software?
>
> Maybe another pic would be more suitable (with an A/D build in)?
> At the time we lack an eprom-programmer though.
>
> Any suggestions welcome.
>
> /Henrik & David
>

The short answer is no.  The '84 does not have anywhere near enough
resources to perform real-time FTs.  Even 'touch-tone' decoding
is a challenge.

You are better off using 7 analogue band pass filters and sampling
the output peaks.  This could be done with a MUX input ADC such as
the PIC16C74, or an external unit such as NSC's ADC8017 (16 input).

If this seems like too much hardware, then use a DSP such as TI's
DSP320Cxxx series.  I think some have inbuilt ADCs.

Regards,
SJH
Canberra, Australia