#include <c8051f020.h>

//------------------------------------------------------------------------------------
// 16-bit SFR Definitions for 'F02x
//------------------------------------------------------------------------------------

sfr16 DP       = 0x82;                    // data pointer
sfr16 TMR3RL   = 0x92;                    // Timer3 reload value
sfr16 TMR3     = 0x94;                    // Timer3 counter
sfr16 ADC0     = 0xbe;                    // ADC0 data
sfr16 ADC0GT   = 0xc4;                    // ADC0 greater than window
sfr16 ADC0LT   = 0xc6;                    // ADC0 less than window
sfr16 RCAP2    = 0xca;                    // Timer2 capture/reload
sfr16 T2       = 0xcc;                    // Timer2
sfr16 RCAP4    = 0xe4;                    // Timer4 capture/reload
sfr16 T4       = 0xf4;                    // Timer4
sfr16 DAC0     = 0xd2;                    // DAC0 data
sfr16 DAC1     = 0xd5;                    // DAC1 data

#define SYSCLK 2000000

void PORT_Init (void);
void Timer3_Init (int counts);
void Timer3_ISR (void);

void main(void)
{
	// disable watchdog timer
   WDTCN = 0xde;
   WDTCN = 0xad;
	
   PORT_Init ();
   Timer3_Init (SYSCLK / 3/ 10);        // Init Timer3 to generate interrupts
                                          // at a 10Hz rate.

   EA = 1;											// enable global interrupts

   while (1) {                            // spin forever
   }
}

void PORT_Init(void)
{
	XBR2=0xF0;
	P74OUT=0x03;
	P4=0x01;
}

void Timer3_Init (int counts)
{
   TMR3CN = 0x00;                      // Stop Timer3; Clear TF3;
                                       // use SYSCLK/12 as timebase
   TMR3RL  = -counts;                  // Init reload values
   TMR3    = 0xffff;                   // set to reload immediately
   EIE2   |= 0x01;                     // enable Timer3 interrupts
   TMR3CN |= 0x04;                     // start Timer3
}

void Timer3_ISR (void) interrupt 14
{
   TMR3CN &= ~(0x80);                     // clear TF3
   P4<<P4;                            // change state of LED
}