void DAC_CONFIG(void)
{
    DAC_SetInMode();//浮空输入
    CLK_PeripheralClockConfig(CLK_Peripheral_DAC,ENABLE);
    CLK_PeripheralClockConfig(CLK_Peripheral_COMP,ENABLE);
    DAC_DeInit();
    DAC_Init(DAC_Channel_1,DAC_Trigger_T4_TRGO,DAC_OutputBuffer_Enable);
    DAC_Cmd(DAC_Channel_1,ENABLE);
    SYSCFG_RIDeInit();
    SYSCFG_RIIOSwitchConfig(RI_IOSwitch_14,ENABLE);
    DAC_DMACmd(DAC_Channel_1, ENABLE);  
    //DAC_SoftwareTriggerCmd(DAC_Channel_1,ENABLE);
    DAC_SetChannel1Data(DAC_Align_12b_R,4095);
    //DMA1_Channel1
}