//------------------------------------------------------------------------------------
// Blinky.c
//------------------------------------------------------------------------------------
// Copyright 2001 Cygnal Integrated Products, Inc.
//
// AUTH: BW
// DATE: 4 SEP 01
//
// This program flashes the green LED on the C8051F020 target board about five times
// a second using the interrupt handler for Timer3.
// Target: C8051F02x
//
// Tool chain: KEIL Eval 'c'
//

//------------------------------------------------------------------------------------
// Includes
//------------------------------------------------------------------------------------
#include <c8051f020.h>                    // SFR declarations

//------------------------------------------------------------------------------------
// 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

//------------------------------------------------------------------------------------
// Global CONSTANTS
//------------------------------------------------------------------------------------

#define SYSCLK 2000000                    // approximate SYSCLK frequency in Hz

sbit  LED = P1^6;                         // green LED: '1' = ON; '0' = OFF

//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------
void PORT_Init (void);
void Timer3_Init (int counts);
void Timer3_ISR (void);

//------------------------------------------------------------------------------------
// MAIN Routine
//------------------------------------------------------------------------------------
void main (void) {

   // disable watchdog timer
   WDTCN = 0xde;
   WDTCN = 0xad;
	
   PORT_Init ();
   Timer3_Init (SYSCLK / 12 / 10);        // Init Timer3 to generate interrupts
                                          // at a 10Hz rate.

   EA = 1;											// enable global interrupts

   while (1) {                            // spin forever
   }
}

//------------------------------------------------------------------------------------
// PORT_Init
//------------------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{
   XBR2    = 0x40;                     // Enable crossbar and weak pull-ups
   P1MDOUT |= 0x40;                    // enable P1.6 (LED) as push-pull output
}

//------------------------------------------------------------------------------------
// Timer3_Init
//------------------------------------------------------------------------------------
//
// Configure Timer3 to auto-reload and generate an interrupt at interval
// specified by <counts> using SYSCLK/12 as its time base.
//
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
}

//------------------------------------------------------------------------------------
// Interrupt Service Routines
//------------------------------------------------------------------------------------

//------------------------------------------------------------------------------------
// Timer3_ISR
//------------------------------------------------------------------------------------
// This routine changes the state of the LED whenever Timer3 overflows.
//
void Timer3_ISR (void) interrupt 14
{
   TMR3CN &= ~(0x80);                     // clear TF3
   LED = ~LED;                            // change state of LED
}