Using the comparator on a 28X2

M

MartinM57

Moderator
(yes, I've got my 28X2's so I've now got the questions!)

Manual 1 shows legs 2 to 5 being the comparator inputs. The PIC18F2520 datasheet shows them also and (page 233) indicates that the CMCON register is used to control their operation and determine the comparator output values.

I can't find anything in any (PICAXE) manuals that indicates how to access/use CMCON - is it just left to the programmer to use the appropriate PEEKSFR/POKESFR commands to the right location?

The PIC datasheet shows CMCON at 0xFB4 - how does that map onto the PEEKSFR/POKESFR location parameter which is 0 to 255?

TIA
Martin
 
Technical

Technical

Technical Support
Staff member
You never need to use direct sfr registers for general PICAXE features.
The BASIC command you are missing in this case is 'compsetup' - this will do all the hard work for you! Look it up in part 2 of the manual.

For peeksfr/pokesfr you drop the inital F, so 0xFB4 is $B4
 
M

MartinM57

Moderator
Wow - I completely missed those 4 pages in the manual :redface:

I was searching for C1- C1+ etc which are the pin layout diagrams, but nowhere else.

I think I need to read the new manual cover to cover and post as a last resort :moreredface:

Thanks for the info about mapping SFRs to PEEKSFR/POKESFR locations
 
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