void delay_ms(unsigned char u)
{
    unsigned char i;
    //if crystal frequency is 11.0592 MHz the delay dute to timer is about 70 ms
    for(i=0; i<u; i++)
    {
        TMOD = 0x01;
		TH0 = 0x00;
		TL0 = 0x00;
		TR0 = 1;
		while(!TF0);
		TF0 = TR0 =0;
    }		  
}