Beginner in need of help !!

[robbo78]

Hi Tabsoft, okay had another read at first it was just going over my head. Am I right in saying I need to read bit 6 of CMCON0? So CMCON0.6?

Thanks,
Rob

[Tabsoft]

Exactly!

CMCON0 Register:
bit 6 COUT: Comparator Output bit.
This is the logic bit output of the Comparator.

CM: Comparator Mode = 100


With this setup the comparator is comparing VIN- (CIN-/GP1) to VIN+ (which is not an external pin but it is "From CVREF Module", internal voltage reference)
So you need to look at the description of COUT in the CMCON0 register listed below AND you need to look at Table 8-1 in the DS.
This will help you work out what value CMCON0.6 will be based upon a given input on GP1.
Take note that CINV is a configuration bit within the CMCON0 register that determines the logic polarity of COUT.

COUT: Possible values
When CINV = 0:
1 = VIN+ > VIN-
0 = VIN+ < VIN

When CINV = 1:
1 = VIN+ < VIN-
0 = VIN+ > VIN

[robbo78]

Brilliant! Thanks for the info again your the best! I should be able to get this working how I want it to now, then & only then will I move onto interupt with it.

Thanks again,
Rob

[robbo78]

Hi Tabsoft, I got the comparator working perfectly so I decided to move onto adding an interrupt, which believe it or not hasn't worked. Here is the code I have fully written, maybe you can help where I have gone wrong?

Thanks,
Rob

You will probably have a laugh at this, as its probably completely wrong lol

'PIC 12F683

#CONFIG 
   __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
#ENDCONFIG

PAUSE 20 'wait for hardware to settle

DEFINE OSC 4 '4mhz ocsillator
ANSEL = %00000010 'pin 6 analog
CMCON0 = %00000100 'comparator mode
VRCON = %10101000 'voltage reference
TRISIO = %00000010 'pin 6 input

ON INTERRUPT GOTO SLSELECT 'interrupt handler is slselect
INTCON = %11001000 'enable GIE and GPIE; clear GPIF
IOC = %00000010 ' enable IOC1 (GPIO.1 Interrupt on change)
PIE1 = %00001000 'enable comparator interrupt

POT1 VAR CMCON0.6 'read potentiometer
LED VAR GPIO.2 'led pin 5

ENABLE
main:
HIGH LED 'light led
GOTO main 'repeat

DISABLE 'disable interrupts in handler
SLSELECT:
IF POT1 = 1 THEN 'if <1.1v sleep
NAP 1
ELSE
ENDIF

INTCON = %10001000  'enable GIE and GPIE; clear GPIF
PIR1 = %00000000 'reset CMIF
RESUME 'where left off
ENABLE 'enable interrupts

[Tabsoft]

Glad to hear if Rob.

You did not say what is happening only that it is not working.
I took a look at your code and several things jump out at me.

1. You are jumping into the deep end of the pool with testing "nap"
If would take a smaller step first. Set a flag in the ISR and resume. Then in the main act on the flag you set in the ISR.
This way you can see the effects of the ISR logic.
2. You have IOC.1 enabled, which is GP1, which you are using for the comparator. You need to comment out IOC.1.
3. You are not testing for which Interrupt is firing inside of your ISR. It is almost always a good practice to determine what interrupt caused the jump to the ISR.
4. At the end of your ISR you are not setting the INTCON register they way you think. I believe you have a typo in the value you are assigning to it.


I changed your code to the following which shows the changes.

'PIC 12F683

#CONFIG 
   __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
#ENDCONFIG

PAUSE 20 'wait for hardware to settle

DEFINE OSC 4 '4mhz ocsillator
ANSEL = %00000010 'pin 6 analog
CMCON0 = %00000100 'comparator mode
VRCON = %10101000 'voltage reference
TRISIO = %00000010 'pin 6 input

ON INTERRUPT GOTO SLSELECT 'interrupt handler is slselect
INTCON = %11001000 'enable GIE and GPIE; clear GPIF
'IOC = %00000010 ' enable IOC1 (GPIO.1 Interrupt on change)
PIE1 = %00001000 'enable comparator interrupt

POT1 VAR CMCON0.6 'read potentiometer
LED VAR GPIO.2 'led pin 5

bitTest var bit 'Debug test bit.  Set/Clear in ISR and Check in maiin

bitTest = 0

ENABLE
main:
    
    'HIGH LED 'light led
    LED = bitTest
    
GOTO main 'repeat

DISABLE 'disable interrupts in handler
SLSELECT:
    'IF POT1 = 1 THEN 'if <1.1v sleep
        'NAP 1
    'ELSE
    'ENDIF
    if PIR1.3 = 1 then  'Comparator Interrupt fired (must be cleared before resume)
        bitTest = POT1
    endif

    'INTCON = %10001000  'enable GIE and GPIE; clear GPIF
    INTCON =%11001000 
    PIR1 = %00000000 'reset CMIF
    RESUME 'where left off
    ENABLE 'enable interrupts

See if this gets you along further.

[robbo78]

Hi Tabsoft, okay thanks for all that. I will go back to flagging. I think I was
Getting a bit ahead of myself lol.

Let you know how it goes

[robbo78]

Hi, okay I've been playing about with comparator interrupt now & think I have got the hang of it using flags. The code below is something little I came up with

Now I think I would like to implement the nap command now, or do you think I should learn something else before jumping to the nap command?

Thanks again,
Rob

'PIC 12F683

#CONFIG 
   __config _INTRC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_OFF & _CP_OFF
#ENDCONFIG

PAUSE 50 'wait for hardware to settle

DEFINE OSC 4 '4mhz ocsillator
ANSEL = %00000010 'pin 6 analog
CMCON0 = %00000100 'comparator mode
VRCON = %10101000 'voltage reference
TRISIO = %00000010 'pin 6 input

ON INTERRUPT GOTO int1 'interrupt handler is int1
INTCON = %11001000 'enable GIE and GPIE; clear GPIF
PIE1 = %00001000 'enable comparator interrupt

POT1 VAR CMCON0.6 'read potentiometer
LED VAR GPIO.2 'led pin 5
loop1 var word 'loop1 counter

bitTest var bit 'Debug test bit.  Set/Clear in ISR and Check in main

bitTest = 0
Loop1 = 0

ENABLE
main:

IF bittest = 1 THEN 
GOTO FLASH
ENDIF
    
LOW LED

GOTO main


ENABLE
FLASH:



do
for loop1 = 1 to 1000
HIGH LED
PAUSE 1

NEXT LOOP1

for loop1 = 1 to 1000
LOW LED
PAUSE 1

NEXT LOOP1

IF bittest = 0 THEN
GOTO main
ENDIF

LOOP
  
    
DISABLE 'disable interrupts in handler
int1:
    
if PIR1.3 = 1 then  'Comparator Interrupt fired (must be cleared before resume)
BITtest = pot1
ENDIF 

INTCON =%11001000 
PIR1 = %00000000 'reset CMIF
RESUME 'where left off
ENABLE 'enable interrupts