ADC timer definition

[luisfe]

Richard: Thank you very much for your answer. I have studied the manual and it doesn't have the text you showed, surely I have an older version. (if you would have a link) Anyway, thank you. With this information I'm not quite sure about what to do except letting the define_clock at 3. The application doesn't require very fast readings but accurate. I'll read PT100 sensors and I'm now busy making the propper signal conditioner with some op amps. Indeed is a microchip circuit proposal (AN687c document) with little modifications, using the AD of the 4550 instead of an independent AD, and testing with stereo audio cable to connect the three cables between the pic circuit and the PT100 sensors. Yes it is more entertaining than TV, maybe not more than, for instance, "Obsession" movie, with Juliette Binoche (my girlfriend) and Jeremy Irons. Have a good day.

[richard]

I have studied the manual and it doesn't have the text you showed, surely I have an older version. (if you would have a link)

http://melabs.com/resources/index.htm#Manuals

With this information I'm not quite sure about what to do except letting the define_clock at 3.

for a pic18f4550 @20mHz the rc clock [3] is a poor choice (see data sheet) if you are using the adcin command . for accuracy the device needs to sleep during the conversion according to the data sheet and adcin will not do that

[luisfe]

Thank you again.
Then ADCIN is an instruction nobody should use in order to have precision?
Excuse me but I have another question, If I use the pins dedicated for AN2 and AN3 in another matters, will the ADC have the 5 volts of Vdd as reference as default? (I hope so because I have any pins left) Or I have to use necesarily AN2 and AN3 to specify that reference?
Have a good day or night.
Luis

[richard]

Then ADCIN is an instruction nobody should use in order to have precision?

why would you say that ?
adcin is only an issue if you use that chip [pic18f4550] with the adc clock option 3 [rc] and fosc > 1mHz
with fosc=20mHz adcin is fine with adc clock option 5

If I use the pins dedicated for AN2 and AN3 in another matters, will the ADC have the 5 volts of Vdd as reference as default? (I hope so because I have any pins left) Or I have to use necesarily AN2 and AN3 to specify that reference?

the default powerup state for vcfg is 00, which defaults to vss/vdd for reference

[luisfe]

Thank you very much. I'll use it so and tell you what happens.
Luis