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#include "reg51.h"
typedef unsigned char BYTE;
typedef unsigned int WORD;
//-----------------------------------------------
/* define constants */
#define FOSC 11059200L
#define T1MS (65536-FOSC/12/1000) //1ms timer calculation method in 12T mode
/* define SFR */
sbit TEST_LED = P1^0; //work LED, flash once per second
/* define variables */
WORD count; //1000 times counter
//-----------------------------------------------
/* Timer0 interrupt routine */
void tm0_isr() interrupt 1
{
TL0 = T1MS; //reload timer0 low byte
TH0 = T1MS >> 8; //reload timer0 high byte
if (count-- == 0) //1ms * 1000 -> 1s
{
count = 1000; //reset counter
TEST_LED = ! TEST_LED; //work LED flash
}
}
//-----------------------------------------------
/* main program */
void main()
{
TMOD = 0x01; //set timer0 as mode1 (16-bit)
TL0 = T1MS; //initial timer0 low byte
TH0 = T1MS >> 8; //initial timer0 high byte
TR0 = 1; //timer0 start running
ET0 = 1; //enable timer0 interrupt
EA = 1; //open global interrupt switch
count = 0; //initial counter
while (1); //loop
}
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