blinky.c

来自「CYGNAL单片机」· C语言 代码 · 共 108 行

//------------------------------------------------------------------------------------
// Blinky.c
//------------------------------------------------------------------------------------
//
// This program flashes the green LED on the C8051F020 target board about five times
// a second using the interrupt handler for Timer3.
//
// Target: C8051F02x
//
// Date: 7 JUN 04
//
// Tool chain: SDCC 'c'
//
// Release 1.0
//

//------------------------------------------------------------------------------------
// Includes
//------------------------------------------------------------------------------------
#include <F020.h>                         // SFR declarations


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

#define SYSCLK 2000000                    // approximate SYSCLK frequency in Hz

sbit at 0x96 LED;                         // green LED: '1' = ON; '0' = OFF

//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------
void PORT_Init (void);
void Timer3_Init (int counts);
void Timer3_ISR (void) interrupt 14;


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

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

   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
   TMR3RLH  = (-counts) >> 8;          // Init reload values
   TMR3RLL  = (-counts);               // Init reload values
   TMR3H    = 0xff;                    // set to reload immediately
   TMR3L    = 0xff;                    // 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
}