Post by thread:[PIC] 18f452 and PWM

Hi all, I was wondering if anyone knows if both PWM's on a PIC 18f452 can be used simultaneously? I know that the frequency and period have to be the same, but i need to vary the duty cycles on each. That is, one (CCP1) is controlling the variable speed of a DC drive motor (varying duty cycles), whereas the other (CCP2) needs to control a DC motor that also needs a varying duty cycle. Both at the same time. I have been trying to get it to work but it seems to only control one at a time. Thanks Jason

On Sun, 27 Feb 2005, Jason Graham wrote: > I was wondering if anyone knows if both PWM's on a PIC 18f452 can be used > simultaneously? Yes. > I know that the frequency and period have to be the same, Correct. > i need to vary the duty cycles on each. That is, one (CCP1) is controlling > the variable speed of a DC drive motor (varying duty cycles), whereas the > other (CCP2) needs to control a DC motor that also needs a varying duty > cycle. Both at the same time. I have been trying to get it to work but it > seems to only control one at a time. Show how you've set up the CCPxCON and CCPRx registers. -- John W. Temples, III

>>Show how you've set up the CCPxCON and CCPRx registers. Using Pic Basic Pro el crappo.... DEFINE HPWM2_TIMER 2 ' timer 2 select DEFINE CCP1_REG PORTC DEFINE CCP1_BIT 2 DEFINE HPWM1_TIMER 2 DEFINE CCP2_REG PORTB DEFINE CCP_BIT 3 and initialization registers CCP1CON = %00001100 'PWM mode CCP2CON = %00001100 'PWM mode __________________________________________________ the following applies to change the duty cycle and output pulse HPWM 1,255,2000 Jason

HPWM uses the *hardware* PWM module. It will not work on RB3. DEFINE HPWM2_TIMER 2 DEFINE CCP1_REG PORTC DEFINE CCP1_BIT 2 ' RC2/CCP1 DEFINE HPWM1_TIMER 2 DEFINE CCP2_REG PORTC DEFINE CCP_BIT 1 ' RC1/CCP2 TRISC.1=0 TRISC.2=0 CCP1CON = %00001100 'PWM mode CCP2CON = %00001100 'PWM mode HPWM 1,55,2000 ' RC2/CCP1 = 2kHz @ 50% duty HPWM 2,127,2000 ' RC1/CCP2 = 2kHz @ 21% duty ^_____ change this value to adjust duty cycles -Bruce http://www.rentron.com {Quote hidden}> >>Show how you've set up the CCPxCON and CCPRx registers. > > > Using Pic Basic Pro el crappo.... > > DEFINE HPWM2_TIMER 2 ' timer 2 select > DEFINE CCP1_REG PORTC > DEFINE CCP1_BIT 2 > > DEFINE HPWM1_TIMER 2 > DEFINE CCP2_REG PORTB > DEFINE CCP_BIT 3 > > > and initialization registers > > CCP1CON = %00001100 'PWM mode > CCP2CON = %00001100 'PWM mode > > __________________________________________________ > the following applies to change the duty cycle and output pulse > > HPWM 1,255,2000 > > Jason > > > --

> HPWM 1,55,2000 ' RC2/CCP1 = 2kHz @ 50% duty > HPWM 2,127,2000 ' RC1/CCP2 = 2kHz @ 21% duty > ^_____ change this value to adjust duty cycles Sorry. Should read; HPWM 1,55,2000 ' RC2/CCP1 = 2kHz @ 21% duty HPWM 2,127,2000 ' RC1/CCP2 = 2kHz @ 50% duty -Bruce http://www.rentron.com

I have all three working on mine, there is the code: ;############################################################################ ; Author : Antonis Iliopoulos ; ; Date : 03 / 02 / 05 ; ; Title: 3CCP ; ; ; ; Description: The following program was created to produce a PWM signal through the ; ; all three CCP channel on RC2, rb3 and rb5 that will set the motors to a fixed position by entering the appropriate value in CCPRxL ; ; ; ;############################################################################ list p=16f777 include<p16f777.inc> ;------------------------------------------------------------ ;internal oscillator at 4 MHz ;------------------------------------------------------------ duty equ 0x20 duty2 equ 0x23 duty3 equ 0x24 #define ccp1 portc,2 #define ccp2 portb,3 #define ccp3 portb,5 ;ERRORLEVEL -302 org 0x000 start ; bsf status,rp0 ; bcf status,rp1 ;switch to bank 1 banksel OSCCON movlw b'01100000' ;Device is running from INTRC as a secondary system clock movwf OSCCON ; T1OSC is used for system clock at a stable frequency of 1MHz movlw b'00000000' ;Device is running from INTRC as a secondary system clock movwf OSCtuNe ; T1OSC is used for system clock at a stable frequency of 1MHz movlw b'00000000' ;with 1 set inputs and with 0 set outputs movwf trisb^0x080 ; portB is all outputs bcf trisc,2 ;We clear ccp1 pin to make it output reference: 14.5 bcf status,rp0 ;bank0 bcf ccp1 ;we set the ccp1 pin low BANKSEL TRISC ;GO TO THE APPROPRIATE BANK bsf status,rp0 bcf trisc,1 ;We clear ccp2 pin to make it output reference: 14.5 bcf status,rp0 ;bank0 bcf ccp2 ;we set the ccp2 pin low bcf trisb,5 ;We clear ccp1 pin to make it output reference: 14.5 bcf ccp3 ;we set the ccp1 pin low bcf status,rp0 bcf intcon,7 ;disable global interrupts bcf intcon,6 ;disable peripheral interrupts bsf status,rp0 ;bank 1 bcf pie1,1 ;disable timer 2 interrupts bcf pie1,2 ;disable ccp1 interrupts bcf pie2,0 bcf pie2,1 banksel pir1 clrf pir1 clrf pir2 bcf status,rp0 ;BANK 0 clrf ccp1con ;ccp1 module off clrf ccp2con ;ccp2 module off banksel ccp3con clrf ccp3con ;ccp3 module off bsf status,rp0 bcf status,rp1 ;bank 1 movlw b'11111111' ;decimal 255 FOR MAX RES=10 BITS movwf pr2 ;load period register bcf status,rp0 bcf status,rp1 ;bank 0 bsf ccp1con,5 ;clear bit 1 of duty cycle reg bcf ccp1con,4 ;clear bit 0 of duty cycle reg - pwm movlw b'00101011' ;DUTY CYCLE movwf duty movwf ccpr1l ;bits 9-2 of duty cycle bsf ccp2con,5 ;clear bit 1 of duty cycle reg bcf ccp2con,4 ;clear bit 0 of duty cycle reg - pwm movlw b'10001010' ;DUTY CYCLE movwf duty2 movwf ccpr2l ;bits 9-2 of duty cycle bsf status,rp0 bcf status,rp1 ;bank 1 bcf ccp3con,5 ;clear bit 1 of duty cycle reg bcf ccp3con,4 ;clear bit 0 of duty cycle reg - pwm movlw b'01001010' ;DUTY CYCLE movwf duty3 banksel ccpr3l movwf ccpr3l ;bits 9-2 of duty cycle bcf status,rp0 bcf status,rp1 ;bank 0 movlw b'00000011' ;prescaler = 0 to be 1, 1 to divide by 4, 1x for 16 movwf t2con ; tmr2 off clrf tmr2 ;clear tmr2 movlw b'00001100' ;ccp1 pwm mode, ccp1 module on movwf ccp1con movlw b'00001100' ;ccp1 pwm mode, ccp1 module on movwf ccp2con banksel ccp3con movlw b'00001100' ;ccp1 pwm mode, ccp1 module on movwf ccp3con banksel t2con bsf t2con,2 ;tmr2 on errorlevel +302 end regards Antonis Send instant messages to your online friends http://uk.messenger.yahoo.com

The PBP 18F452.INC header file doesn't include the CONFIG3H CCP2MX: CCP2 Mux bit so CCP2 defaults to RC1. Add this to your PBP 18F452.INC file or turn off CCP2 MUX with you programmers software before programming the part. __CONFIG _CONFIG3H, _CCP2MX_OFF_3H With CCP2MX off, RB3 will be the CCP2 input/output. Then this should work for RB3. DEFINE HPWM2_TIMER 2 DEFINE CCP2_REG PORTB DEFINE CCP2_BIT 3 HPWM 2,127,2000 ' Output 2kHz on RB3 @ 50% duty -Bruce http://www.rentron.com

Hi Bruce Thanks for the help Jason

Antonis Thanks for the help Jason

Not a problem - if you need any further help and I can assist, just e-mail me!!! By the way waht is the project for? Jason Graham <spam_OUTjgrahamcaTakeThisOuThotmail.com> wrote: Antonis Thanks for the help Jason