disp_buff[20]
void lcdMemCpy(char *dist,char *src,char start,char len)
{
	//clear
	char i,j,first_byte,total_byte;
	char first_left;
	j=8-first_left;
	first_byte = start/8;
	*dist &= (0xFF<<j);//clear first byte left bit
	total_byte = len/8;
	for(i=start;i<start+len;i++)
	{
		*(dist+first_byte+i)=0;	
	}
	
}