generate sine wave

[prasadezoysa]

I am developing an online ups system. I want to get a sine wave by using pwm method. Can anybody assist me regarding this matter? and also need some code.

Thanks
Prasa
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sanjeewa

[PCM programmer]

Read these threads:
http://www.ccsinfo.com/forum/viewtopic.php?t=36540

http://www.ccsinfo.com/forum/viewtopic.php?t=26636
http://www.ccsinfo.com/forum/viewtopic.php?t=25865
http://www.ccsinfo.com/forum/viewtopic.php?t=28480

[asmboy]

If you want HIGH purity sine functions,
and excellent frequency accuracy ( within .002% of 60 hz)
and wide frequency programmability i suggest you look at the AD9833

I use it in an instrument that has to have .01 hz accuracy from 1 hz to 100 khz - and this part does it to perfection.

The AD9833 it produces a 10 bit accuracy very high purity sine wave
with not too much SPI programming --

I use it several devices and found an EZ way to drive it - using hardware SPI on the PIC.

the secret is to use an EXACT power of 2 as the oscillator reference.
I use 8.388608 and 4.194304 mhz.

programming the part becomes pretty EZ - as all the
divisors are arrived at by simple shifting.

The basic setup is stored as a couple of constants that I initialize it with at system start, and thereafter - you just pump it new divisors to chaneg frequency or switch to square or tri wave output.

Multiple units can be digitally PHASE synchronized by the pic to create precise 3 phase 60 hz signals if you like that sort of thing too.

I admit that as a 60 hz ref its probably overkill
but you will never match the accuracy or purity with simpler circuits,
or trying to filter a PWM signal.
( BTW - you wil be hard pressed to use PWM to make a 60 hz signal
anyway unless you have a ridiculously LOW PIC master osc freq. )