A simple example of counting with a timer

/*
Note: This program mainly shows how to use the timer to count, and reflects the modular sub-functions. It is a relatively simple program
*/

#include //header file
#define uchar unsigned char //macro definition
#define uint unsigned int
uchar count; //define global variables
void display_led() //led display sub-function
{
if(count==20) //changes every 1S (crystal oscillator: 12MHZ)
{
count=0; //count cleared for next count
P2=~P2; //P2 value inverted
P2=P2<<1; //P2 value shifted left
P2=~P2;
if(P2==0xff) //if the last LED is on,
P2=0xfe; //then the first LED is on
}
}
void init() //initialization sub-function
{
EA=1; //turn on total interrupt
ET0=1; //turn on timer interrupt
TR0=1; //start timer
TMOD=0x01; //T0 working mode 1, 16-bit counting
TH0=(65536-50000)/256; //Set the initial value of the timer
TL0=(65536-50000)%256;
P2=0xfe; //Assign initial value to P2 port
while(1)
{
display_led(); //Call LED display sub-function
}
}
void main() //Main function
{
init(); //Call initialization sub-function
}
void delay() interrupt 1 //Timed interrupt sub-function
{
TH0=(65536-50000)/256;
TL0=(65536-50000)%256;
count++; //Count variable plus 1
}