At 06:12 PM 4/7/2004 +1000, you wrote:
>Can anyone advise where I can find a PIC design and code for the following
>application?
>
>Simultaneous generation of 3 sinewaves of differing frequency and
>amplitude. Due to cost and parts count, one IC and lookups are preferred
>over filtering.
>
>The frequencies are all below 30 Hz (subaudio). Amplitudes are 3 to 5 volts.
>
>If there is no ready-made design, perhaps someone who is interested in
>knocking one up for a suitable fee can contact me off-list.
>
>Thanks for your reply.
>
>Peter Nielsen

Peter- I can probably do this for you, using hardware PWM and lookup
tables. I have already generated the tables for another project
(motor controller). Suggest using a PIC with at least 3
HARDWARE PWM outputs.

Please let me know if you would be interested (and some idea of your
budget).

If you want to do it yourself, it's not that hard. You need to adopt
a "phase accumulator" approach as used in DDS chips to synthesize the
frequency and you need to crunch numbers for the amplitude, but at 30Hz
it should be okay.

This is the sort of thing that those dsPICable new chips will be very
good at.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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