12F683 Comparator Problems

[morethanenuf]

I'm relatively new to PICBasic Pro. I am having a very hard time initializing the comparator and then using it. I want to run a test using the 12F683's comparator and a digital pot as a reference voltage. The digital pot would be programmed by a 16F877 running the main program while the 12F683 will be running monitor program and send an interrupt to the 877 when the comparator is toggled. I would like the output of the comparator to be available outside the PIC. In reading the spec I found that "CMCON0 = 1" is the only thing I could find to initialize the comparator. After this I am at a loss for how to use the comparator. If anyone can help or point me to a webpage or an article I would be forever greatful. Thanks in advance.

[mister_e]

really far of what you need but here's an example with a 12f675 i did many months ago using the internal comparator

@ __config _INTRC_OSC_NOCLKOUT & _MCLRE_OFF  ;config fuse

TRISIO = %11001111 ;GPIO.4, GPIO.5 as output
CMCON=%00000010 ;COUT=1 when Vin+(GPIO.0) > Vin- (GPIO.1)
				;comparator mode :comparator without output
ANSEL=0 ;turn off analog to digital

Clip     var   GPIO.4
Normal   var   GPIO.5
Speaker  var   byte

start:
	  speaker=CMCON.6 ;read from internal comparator
      Select case speaker
             case 0
                  clip=0
                  normal=1
             case 1
                  clip=1
                  normal=0
                  pause 100
                  Clip=0
      end select
	  goto start

[morethanenuf]

Thanks for the help. I understand how your code works, but I still can't get the comparator to work as far as I can tell. All I'm trying to do now is use 2 pots as the analog inputs Vin+ and Vin- and use COUT to turn an led on and off. Is there a drive problem with the comparator? Do I have to use the internal output as a signal to drive a separate pin HIGH or LOW?

[mister_e]

By looking the datasheet, the comparator will be GP2 and must be set as digital and can sink/source +/- 25mA