18f4680 pwm

[Macgman2000]

Hello,

I am trying to use the ECCP for a full H-bridge. I can not seem to get it working, any help would be appreciated in resolving my issue... see below.

       	INCLUDE "Modedefs.Bas"    
 	DEFINE OSC 20

 		
; Set port direction and turn off unused peripherals
        CMCON  = 7          			' shut offcomparators
        TRISA = %00011111				' Set PORTA to input "1" or output "0"
        TRISB = %00000000    			' set portB to output "0" or input "1"
        TRISC = %00000000
        TRISD = %00000000
        TRISE = %00000000
        
        ADCON1 = %00001111				' bit 0 ~ bit 3 sets ports as digital I/O. 1 = digital, 0 = analog
        ADCON0 = %00000000              ' bit 0 disables A/D converter module.
        ECCP1CON = %00000000            ' bit 0 ~ bit 3 turns off capture/compare/PWM
        
        
; Declare variables and aliases

duty var byte

PAA var LATA
PBB var LATB
PCC var LATC                             
PDD var LATD                          ' used to re/set portD.1, can not use portd.1 = x on latch ports
PEE var LATE


; initialize power on state of ports
LATA = 0
LATB = 0
LATC = 0
LATD = 0                                ' force latches on portD to low
LATE = 0


        ECCP1CON = %11001100            ' bit 0 ~ bit 3 turns off capture/compare/PWM
        T2CON = %00010101		         ' Turn on Timer2, Prescale=4
        PR2 = 249				         ' Set PR2 to get 5KHz PWM out
         
        duty = 100                      
        ECCPR1L = DUTY
        ECCP1CON.4 = duty.0		            
        ECCP1CON.5 = duty.1		            
               
         
Mainloop:
        
       pauseus 1000
         
      goto mainloop

[Macgman2000]

It works as is.... traces lifted off PCB...

[WOZZY-2010]

I played with this code a little today and it works well....Thanks

Just a few minor changes can give 10 bits PWM resolution.

Change duty var byte to duty var word.

Add the line ECCPR1L = duty >> 2 after ECCP1CON.5 = duty.1.

now the duty cycle can be set from 0 to 1023 instead of 0 to 255.

Bob W.