Help changing CCP3 output pin

[ChrisHelvey]

Hello experts,

Yes, I live in NoobieVille.

I am using a 16f877a and have a need to use a 3rd PWM output, which I found code from Bruce on how to do this. So far so good. It follows below.

However, I can't find how to change the output for CCP3 to use an alternate pin. All my Port A (A/D channels,) Port B (user input,) and port D (user input,) are used. Port E is multiplexed to ADCON inputs according to the datasheet. But I could use pin C.3,4,5,6,or 7. And after all outputs for the other PWMs are on C.1 and 2, so the next C pin would be logical.

Is it even possible to do it?

Thanks a bunch for any guidance. The project is coming along nicely and I am pretty excited when stuff works right. I'm learning, albeit S-l-o-w-l-y. I'm gettin' older...

Here is Bruce's contribution form a previous post about using 3 HPWMs:


-----------------------------------------------------------------
Duty1 var Byte 'Variable for controlling the PWM in CCP1
Duty2 Var Byte 'Variable for controlling the pwm in CCP2
Duty3 Var Byte 'Variable for controlling the PWM in CCP3


CCP1CON = %00001100 'Using CCP1 as PWM Mode Register 9-1 in Datasheet
CCP2CON = %00001100 'Using CCP2 as PWM Mode Register 9-1 in Datasheet
CCP3CON = %00001100 'Using CCP3 as PWM Mode Register 9-1 in Datasheet
T2CON = %00000101

TRISC.2 = 0 'Setting the CCP1 PIN as OUTPUT
TRISC.1 = 0 'Setting the CCP2 PIN as OUTPUT
TRISB.5 = 0 'Setting the CCP3 PIN as OUTPUT

Duty1 = 0
Duty2 = 0
Duty3 = 0


' Fosc = Clock Frequency (4MHz)
' PS = Timer2 Prescale Value (T2CON<1:0>)
' Freq = PWM output frequency
' Duty% = Duty cycle (20% = 0.2)

' formulas:
' PR2=(Fosc/(4*PS*Freq))-1
' CCPR1L:CCP1CON<5:4>=(PR2+1)*4*Duty%

PR2 = 50 with prescalar of 4 in Timer2

For i = 0 to 200
Duty1 = Duty1 + 1
CCP1CON.4 = Duty1.0
CCP1CON.5 = Duty1.1
CCPR1L = Duty1 >> 2
Pause 17
Next i

For i = 0 to 200
Duty2 = Duty2 + 1
CCP2CON.4 = Duty2.0
CCP2CON.5 = Duty2.1
CCPR2L = Duty2 >> 2
Pause 17
Next i


for i = 0 to 200
Duty3 = Duty3 + 1
CCP3CON.4 = Duty3.0
CCP3CON.5 = Duty3.1
CCPR3L = Duty3 >> 2
Pause 17
Next i

[ChrisHelvey]

Oops, looks like this won't work with the 16f877A. I get an undefined CCP3CON Symbol error.

[Bruce]

Looks like you might have stumbled onto a code example for a 16F7X7 type with 3 CCP
modules. Unfortunately the 877A only has two.