参考TI例程如下：
interrupt void cpu_timer0_isr(void)
{
   CpuTimer0.InterruptCount++;

   // Acknowledge this interrupt to receive more interrupts from group 1
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;
}

我将程序做修改如下：
interrupt void cpu_timer0_isr(void)
{
   Dout8 = 1;
   Dout7 = 1;
   ad_conv();
   Dout7 = 0;       
   DA_Out();       
   Dout8 = 0;
   PieCtrlRegs.PIEACK.all = PIEACK_GROUP1;// Acknowledge this interrupt to receive more interrupts
                                                                 //from group 1  PIEACK_GROUP1=1
}
用示波器测得 Dout7输出正常， Dout8输出为50us的窄脉冲；C:UsersAdministratorDesktop