/************************************************************************/
/*                           看门狗启动                                  */
/*参数：                     tim: 看门狗预分频                            */
/************************************************************************/
void WDT_on(unsigned char time)
{
 unsigned char teep;
 
 asm("WDR");
 teep = ((time&0X08)<<2) | (time&0X07) | (1<<WDE);
 teep = (1<<WDIF) | (1<<WDIE) | (1<<WDE) | teep;
 
 /*MCUSR 中的WDRF 清零*/
 MCUSR = 0x00;
 /* 置位WDCE 与WDE 中断模式*/
 WDTCSR = (1<<WDCE) | (1<<WDE);
 /*开启WDT并初始化定时器,看门狗中断使能*/
 WDTCSR = teep;
 
}