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C Code to calculate RMS of sine-wave

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neuralc

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c code rms

Hi all,

Some one have a C code (for embedded) to calculate the RMS value of the sine-wave readed by an ADC of 8 bits?

ThX


NeuralC
 

Hi neuralc,

It is very simple,

Consider your line frequency = 50.00 Hz

50.00 Hz = 20ms = 20000 us

for example if you grab sinewave sample @ 100us interval time you get 200 samples .

store in some buffer, your ADC is 8 bit so you need buffer of size
signed char adcbuf[200]

ok...

now do following

signed int rawrms ;
int rms ;

for( count = 0 ; count < 200 ; count++ )
{
rawrms += adcbuf[count] * adcbuf[count] ;
}

rms = rawrms / 200 ;
rms = sqrt(rms) ;

after squartrooting

you get actual rms of sinewave.


Regards.

Zastereo
 
OK, Thx,

Like this we get the RMS for one cicle, but what about cicle to cicle, we make the average?


ThX

NeuralC
 

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