1st time COMPARATOR use...

[paul borgmeier]

would you know a tutorial about the use of Comparator? I'm getting lost more and more...

See Melanie's post here
http://list.picbasic.com/forum/messages/3064/3607.html?

[flotulopex]

Yes Paul, I read Melanie's tutorial. At my level of comprehension, it is more like an example using a Comparator module in a 16F628.

Yes Darrel, I read the MICROCHIP's Comparator Tips & Tricks document.

The problem is, I don't clearly understand all the different pin/port/register names described in the datasheet. If some of them are obvious to me (VRef, A, D, etc..), others are not (CINV, VIN, CIN, etc..).

Sorry if this sounds stupid and looked easy as a conventional ampli-op before I started, but all the µC-specific terminology messes my mind up.

Just an example; when I read the 12F765's datasheet Comparator Operating Modes, I get lost at the very first figure....
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1703&stc=1&d=118095092 1">
Here, I assume I have to set ports GPIO.0 & GPIO.1 to Analog (ANSEL register); is this right? But what is with the Output? Is it going to turn to an "1" when CIN+ > CIN-? How will I use it?

And now, is it just the same as before but when the condition is CIN+ > CIN-, does COUT (bit) go to a "1"?
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1704&stc=1&d=118095155 5">

What are CINV, VIN, CIN and what are they doing exactly?

It's confusing me.

[flotulopex]

Okay, after some more trials and a correct connection to GP1 (... not GP0!!!), I got it working.

BUT how do I improve the accuracy?

When the measured voltage ist between 2,3V and 2,6V, my led flickers.

How do I fix this?

Another strange thing: if I "forget" to set the GP1 input as Analog (ANSEL), it still works(!?).

BTW, here are my corrected schema and code:
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=1708&stc=1&d=118097654 5">

' Fuses
@ DEVICE PIC12F675,INTRC_OSC_NOCLKOUT ;Internal oscillator 4MHz
@ DEVICE PIC12F675,WDT_OFF
@ DEVICE PIC12F675,PWRT_ON
@ DEVICE PIC12F675,MCLR_OFF
@ DEVICE PIC12F675,BOD_OFF
@ DEVICE PIC12F675,PROTECT_OFF
@ DEVICE PIC12F675,CPD_OFF

'-------------------------------------------------------------------------------
' Registers    76543210
OSCCAL      = %10000000 'Center frequency - used with Internal 4MHz OSC
TRISIO      = %00000010 'Set Input/Output
GPIO        = %00000000 'Ports High/Low
WPU         = %00000000 'Weak pull-ups (check OPTION_REG)
OPTION_REG  = %10000000 'Pull-ups / Interrupt / Prescaler
ANSEL       = %00000010 'Analog I/O
CMCON       = %01000100 'Comparator Module settings
VRCON       = %10101100 'Voltage reference (= 2.5V)

'-------------------------------------------------------------------------------
' Variables
BatVal   var CMCON.6
BatLoLED var GPIO.2

'-----------------------------------------------------------------------------
' Program
Pause 1 'Delay to allow for VREF to settle
MAIN: 
    BatLoLED = BatVal
    pause 10
    Goto Main
End