// PWM 
#include <REG1210.H>
#define XTAL 2			// Actual Crystal = 1.8432 MHz for MSC1210-DAQ-EVM
#define OneUsConst (XTAL-1)
#define CLEAR 0
#define SET  1
sbit p33=P3^3;
sbit p14=P1^4;
unsigned int p,d;		// Temporary for Period and Duty

void pwm_isr( void) interrupt 2 //External Interrupt 1
{ 	p14=!p14;			// debug
	PWMCON &= 0xef;		// select PWMPeriod
	PWM=p;				// Set PWMPeriod
	PWMCON |=0x10; 		// select PWMDuty 
	PWM=d;
	IE1=CLEAR;  		// Clear pending interrupt
	EX1=CLEAR;
}

void setpwm(unsigned int period, unsigned int duty)
{ 	p14=!p14;  			// debug
 	p=period; d=duty;	// Save for use by the interrupt
 	IE1=CLEAR;  		// Clear any pending interrupt
	EX1=SET;  			// Enable *INT1 pin interrupt
}

void main(void)
{ char i;
	// Setup External INT1 
	IT1=SET;  			// Config *INT1 pin for falling edge trigger
	EA=SET;   			// Global Int Enable 
 
 	PDCON &= 0x0ed; 	//turn on tone gen & sys timer
 	USEC = OneUsConst;
 	p33=1;   			// turn on P3.3 
 	PWMCON=0;  			// select PWMPeriod
 	PWM=500;  			// Set PWMPeriod
 	PWMCON=0x10; 		// select PWMDuty 
 	PWM=200;
 	PWMCON=0x19; 		// Enable PWM
 	for (i=0;i<5;i++) {;}
 	setpwm(200,100); 	// set period/duty after current PWM cycle
 	while(1) {} 
}