Which micro comes with RMS reading for AC voltage?

[atomlcp]

HELP ! Peripheral!!!

Please, anybody please tell me is there any microcontroller come with a RMS reading for a AC voltage?

I need to do a comparation for a control refer to the RMS value for few AC voltage.

Please Help!!

Thank.

 

[throwaway18]

Reading AC voltage with microcontroller

Use descriptive subject lines for your threads.

There are two options.
You can use a DSP chip with enough MIPS, ADC resoloution and ADC bits to digitise the AC signal and work out the RMS value in software.

Alternativley you can use an RMS to DC converter chip such as LTC1966.

Either way you will probably need some gain/attenuation, isolation, level shift and transient protection for the micro.

 

[bamdad]

Re: HELP ! Peripheral!!!

if the AC voltage is in the line frequency range, say, less than few 100Hz, you can use some microcontroller with on-chip adc, like atmega8 and then process the samples to get the RMS value.

 

[atomlcp]

Re: HELP ! Peripheral!!!

Thanks alot. I think using the RMS convert to DC is better isnt it? Can save more processing time for the microcontroller.

 

[bamdad]

Re: HELP ! Peripheral!!!

It would depend, for a multi MIPS processor like the AVR Mega series, that might not be of serious concern. then I prefer to use less components, and make the board more compact

 

[guttinasrinivas]

Re: HELP ! Peripheral!!!

Obviously, reducing component count is one of the design considerations. But the advantage of considering a seperate RMS to DC converter is, independance of frequency range, if it really matters!

 

[frankys]

Re: HELP ! Peripheral!!!

if the AC voltage is in the line frequency range, say, less than few 100Hz, you can use some microcontroller with on-chip adc, like atmega8 and then process the samples to get the RMS value.

I'm working with the atmega32 and a crystal of 12Mhz, do you think that its posible to calculate the rms value? do you have source code?

Please [/quote]