Jan-Erik Soderholm: =20 I believe you are correct - as far as I can tell from the docs (DS39564A = page 181) the A/D uses either an external Vref or the Vdd / Vss voltage. = The Block Diagram on this page clearly shows this connection via PCFG0. Unless the input pin is not correctly defined as ANALOG IN in the config.= register, I can't see any reason for full scale being other than Vdd. I= just tried the experiment on my test card and I do read $3ff for an inpu= t from Vdd. Roy J. Gromlich Jan-Erik Soderholm XA (TN/PAC) wrote= : > Peter Onion wrote : >=20 > > I could be totally missing the point here, but looking at the > > data sheet I think the internal reference in only 3v ? So > > inputs greater than this give f.s.d. (0x3f) I think. >=20 >=20 > I don't think there even *is* an internal V-ref for the ADC. > It can use Vdd or an *external* V-ref. >=20 > Are you sure you aren't thinking of the V-ref for the LVD ? >=20 > Jan-Erik. >=20 > -- > http://www.piclist.com#nomail Going offline? Don't > AutoReply us! > email listserv@mitvma.mit.edu > with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body