16F876 ADCON,CMcon,Tris settings

[RFsolution]

Hi

This is the first time I will use a 16F876 asfar as i can read in the forum, some confusion on the port configuration:

I need to have:
RA0-RA3,RA5(AN4) analog in (10bit ADC), RA4 digital out,
RB0-RB3 + RB6,7 digital out,RB4,5 digital input,
RC0-RC5 digital out,RC6+7 TX+RXD usart

I think i have to set:

ADCON1= %00000010 ' sets RA4 to digital,RA0-3,RA5 analog in, (Bit 7 ? Left or right justified ?)
Trisa %00101111
Trisb %00110000
Trisc %10000000

ADCON0= ?
CMCON= ?
how do I set 10bit ADC ?

[Bruce]

Looks good. Write ADCON1= %10000010 for 10-bit.

Note: The 16F876 does not have comparators. The A version does.

[RFsolution]

Thanks Bruce

What if I use the 16F876a version ?

[Bruce]

The A version has comparators so then you would use CMCON = 7. Even though it defaults to this value at POR, it's good to include this so you remember. Some PIC types with comparators don't default to disabled.

A/D looks pretty much the same.

[Melanie]

As well as implicitly disabling the COMPARATORS, I also disable the VOLTAGE REFERENCE MODULE on the 16F877A...

CMCON=7
CVRCON=0

Those two lines are the ONLY differences between the 'A' and the non-A I've ever included.

You can then progress up to the 18F242/252 (with minor ADC software changes), but there's a HARDWARE difference with the ADC's once you go up to the 18F2420/18F2520 series (eg ADCON1 ADC Configuration %xxxx0100 from the 16F876 can't be pin configured on the 18F2420's).

[Bruce]

Good catch Melanie.