Help with the conversion math

[Ioannis]

You mean that at page 156 of the datasheet you saw ADCON1 and at page 157 ADCON2 and concluded that are the same at bit 7 ? They are not and must be setup accordingly to your needs ALL of them. DO NOT rely on power up defaults.

You have to set if not all, the most registers for the PIC to work as expected.

ADCON0, ADCON1, ADCON2 should ALL be set as YOU desire, NOT the PIC's default state. Each register has its own bits for different setting. Otherwise why have dozens of registers if they were all the same?

Ioannis