16F1705 internal Opamp woes

[tumbleweed]

OPA1CON = %1100000          ' Opamp 1 Enabled, SP set.

Isn't that missing a bit?
Try

OPA1CON = %11000000          ' Opamp 1 Enabled, SP set.

For OPAMP1 you have

' RC2  (pin 8)    AN6, Opamp1Out.       ### output - see notes.
' RC1  (pin 9)    AN5, Opamp1in-.       Junction of RF and RG.
' RC0  (pin 10)   AN4, Opamp1in+.       + sense of 0R1 series load resistor.

So, to use these for the opamp:
- set the TRIS bits for RC0, RC1, and RC2
- set ANSEL bits for AN4, AN5, and AN6

[wjsmarine]

Hi Tumbleweed,

You are a star, thank you.

I don't know how I missed that bit, correcting it saw the Opamp spring to life... in fact I tried a bunch of combinations with TRIS and ANSEL and it was difficult to make the Opamp fail to do its job!

It sounds obvious but to use the Opamp as a buffer one needs to remove any feedback resistors (of course).

Thanks again, I hope this is of use to others.

Kind regards,
Bill