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Subject: Re: How generate a 3phase sine wave ?
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Wed, 6 Nov 2002 14:01:51 -0000
NNTP-Posting-Date: Wed, 06 Nov 2002 14:01:43 GMT
Organization: Customer of PlusNet
"Sparky" wrote in message
> "john" wrote in message
> > Could anyone help? I have to generate a three phase sine wave signal
> > that composes of three component, with 120 degree phase different
> > between any two components. The frequency of it has to be adjustable,
> > say from 0Hz to 5Hz. The signal will be amplified for driving some
> > device. I have no idea to start at all, could anyone help and show me
> > some hints. Is there any commercial product available for such ?
> Easiest way is probably a microcontroller with 3 dacs.
> You need a sine lookup table, you only need the first quadrant values, the
> other three quadrants can be generated by inversions.
> Basically have an n bit counter running at 2^n *4 * your output frequency.
> This output via the lookup generates your reference phase via dac1.
> The other 2 phases are generated by adding (2^n*4)/3 and (2^n*4)*(2/3)
> respectively tothe reference, and outputing via dac2 and dac3.
> In the good old days I would have used counters/adders and muxes to drive
> the LUT and dac's.
..... of course I meant "The other 2 phases are generated by adding (2^n)/3
respectively to the reference count, and outputing via the LUT to dac2 and
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