> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Dario Greggio
> Sent: 08 March 2010 10:18
> To: Microcontroller discussion list - Public.
> Subject: [PIC] measuring 220V mains
> 
> I am to use a 24FJxxGA106 to (along other things) measure 220V mains
> voltage with some coarse accuracy, say 1-2%
> 
> I have a small 220->6V transformer, whose inputs goes via a partitor
> (still have to decide, but let's assume it 4K7 - 2K2) to AN2 of the
PIC.
> So, more or less 2Vrms or 3Vpp circa when mains is nominal 220V.

Sorry if this is being obvious, but you will either need to rectify the
output of the transformer or apply a suitable voltage offset in order to
prevent any negative voltages on the PIC pin.

Mike

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