[Sdcc-user] Setting up PWM for PIC 16F628

[Peter C. <pe...@pe...>]

Chaps,

hope this is the correct place.  Can't seem to get PWM working, this is my PWM 
set up routine is below.  Have not tried it in hardware - but gpsim shows the 
correct pin set to an output but it does not have a signal on it.

Thoughts?

Pete

void pwm_setup() {



	//Set PR2 to 255 - set PWM period
	PR2 = 0xFE;

	//Set up timer 2 prescaler which is also used by the PCM module
	//	00	= 	1:1  prescaler
	//	01	= 	1:4  prescaler
	//	1x	= 	1:16 prescaler
	T2CKPS0 = 0;
	T2CKPS1 = 0;

	//With the above settings and 4MHz crystal we are looking at about 3.9 kHz 
PWM
	//period.
	
	//LSB for the PWM period counter, bits 5 and 4 - set to zero
	//CCP1CON = CCP1CON & 207;
	//CCP1CON = CCP1CON | 1 | 2| 4| 8; //set them high!
	CCP1CON = 15;

	//MSB - set at something mid way for testing.  Will be zero for final set up;
	CCPR1L = 0x80;

	//Timer 2 on
	TMR2ON = 1;

	//Set up TRISB bit 3 as output - clear this bit
	TRISB = TRISB & 247;

}


Can post full code and make file if it helps.

Pete

-- 
Peter Chant
http://www.petezilla.co.uk