At 21:22 08/04/99 +1000, you wrote:
>I am 80% finished developing a device which will be used in the
>telephony biz.
>Part ii) is our dillemma.  The 'sound' can only be described as a 'zzzzip'
>tone, increasing pitch, sort of a ramping-up sound.  I guarantee all below
>10kHz, probably lower.

If it's in the telephony biz, it had _better_ be lower, or it won't go down
a phone line (ie under 4kHz, instead of 10 ;-) )

>  The system must recognise the 'zip' and respond

The recognizing bit is probably quite easy, but you might need to give us
some more details of what the actual signal is (ramped sawtooth, sine etc)
to get a more detailed answer.  However, whatever you do, the hard bit is
usually rejecting unwanted signals without rejecting your own- the phone
line can be a bit noisy, so you have to be quite flexible in what you
accept, but not so flexible that a cough or normal voice sound contains
something that you detect.  Wouldn't it be possible to use DTMF and a
standard DTMF decoder chip?

>Our dilemma is whether to use a low range DSP (say $AUS10 each) or try to
>squeeze it on a mid range PIC ($AUS1-3).
>
>*** Can a mid-range PIC handle this?

Maybe, but you might need to specify 'this' in a bit more detail.

>** If we use a DSP, I assume it can light LEDs and read pushbuttons.

But will probably need external circuits to do so, like the latches you
mentioned.

>me who is the 'Arizona Microchip' of DSP suppliers? (cheap, no-nonsense)

Possibly Analog Devices (EZ KIT etc), but it _really_ doesn't compare...
DSPs are good at number-crunching, and fast data transfer, but not so hot
on 'bells and whistles'- microcontrollers are closer to the opposite
extreme... you might need one of each...

Nigel