Stable ADC readings

[Acetronics2]

ADCIN also polls for the ADCON0.1 bit ...

sooo .... aheum, how to tell it ...

Alain

[mister_e]

ADCIN also polls for the ADCON0.1 bit ...

sooo .... aheum, how to tell it ...

Alain

Yeah but we already say some odds with ADCIN in the past on some specific PIC, Microchip are good to change the way register are done, and how things work for PIC to PIC model...

This said, I never use ADCIN myself, but manually write/read ADC registers... it is also a bit less code hungry... down side "may" be when you port your code on another PIC who's not working the same way, or have different register name, bit assignment. big deal

[dream-]

Well if I understood what the problem was I would not be asking here

The fact is that the ADCIN code gives me an oscillating reading, and the manual method gives me a stable value.

I don't know the reason, but I would like to know. This is a 16F688.

[mackrackit]

For what it is worth I agree with Steve.
I tried ADCIN a couple of times and did not like it. Others swear by it though. ..

Keep doing it the way you are.

[mister_e]

I would love to see the whole code with ADCIN. Sometime if you play with some ADC registers, and you place them Before or After the DEFINEs, it may end-up with unexpected results.

[Acetronics2]

Hi,

Found in the Datasheet ...

Note:

The GO/DONE bit should not be set in the
same instruction that turns on the ADC.
Refer to Section 8.2.5 “A/D Conversion

Procedure”.

a beginning of an explanation ???

Alain

[Bruce]

ADCIN doesn't work with port pin aliases. Use ADCIN 2,W0, or define PinProbe as a constant. PinProbe CON 2 would work.

Also ADCIN doesn't setup TRIS, ANSEL or ADCON1. So you end up with Fosc/2 for your A/D clock because ADCON1 defaults to all 0's. So you're way out of spec for a 4MHz osc. Fosc/8 would be a good one to use with 4MHz (see datasheet).