/************************************************
功能：将整形转换为ascii码字符串
示例：dat = 12345   buffer[10]
      转换后
   buffer[0] = '1'
   buffer[1] = '2'
   ...
   buffer[4] = '5'
   buffer[5] = ' '
**********************************************/
void DtoA(unsigned long dat, unsigned char* buffer)
{
  unsigned long tmp = dat;
  char length = 0;   while(tmp != 0)//求出数字的实际长度
  {
    tmp = tmp/10;
    length++;
  }
  buffer[length] = '