gnupic: Setting up CCP2 module
Subject:
Setting up CCP2 module
From:
Rick Mann ####@####.####
Date:
12 Nov 2002 02:29:57 -0000
Message-Id: <FA8B564C-F5E5-11D6-8B50-0030657C1C3A@latencyzero.com>
Okay, I'm having the hardest time figuring out PIC16F877 peripherals.
Every time I think I've learned how to set them up, they jump up and
bite me again.
I'm using the CCP2 module on the PIC (pin PortC:1) to decode IR. I have
an IR detector whose output goes low when there's an IR carrier
present. I've verified that it's working by using a scope.
However, the interrupt is not happening on capture. Here is the code
I'm using to set it up:
> ; ------------------------------------------
> ; Set up the CCP2 module
> ; ------------------------------------------
>
> bsf STATUS,RP0 ; Select bank 1
> bcf STATUS,RP1
>
> bcf PIE2,CCP2IE ; Disable the CCP2 interrupt
> movlw b'11000010' ; PortC outputs 'cept for RX/TX & C:1
> movwf TRISC
>
> bcf STATUS,RP0 ; Select Bank 0
>
> ; The CCP2 pin is already set as an input
>
> movlw b'00000100' ; Capture every falling edge
> movwf CCP2CON
>
> movlw b'00111001' ; Enable TMR1, internal clock, 1:8 prescale
> movwf T1CON
>
> bcf PIR2,CCP2IF ; Clear the CCP2 interrupt flag
>
> bsf STATUS,RP0 ; Select bank 1
> bsf PIE2,CCP2IE ; Enable the CCP2 interrupt
>
> bcf STATUS,RP0 ; Select Bank 0
> bsf INTCON,PEIE ; Enable peripheral interrupts
Elsewhere in the code I enable general interrupts. I know interrupts in
general are working, because other interrupts do happen.
So, what am I forgetting? I want a high-to-low transition on RC1/CCP2
to capture the time value and generate an interrupt. I want Timer 1 to
be prescaled 1:8, and to increment off the instruction clock.
Thanks in advance!
--Rick
