各位老师，求助一个问题：
   最近在学习STM32F334，想实现双路DAC独立输出，根据DEMO改的代码调试过程中，DAC1能正常输出，DAC2寄存器上能看到数据，但硬件管脚上检测不到输出电平。代码如下：

1. void Configure_DAC(void)
   
2. {
   
3.   /*## Configuration of GPIO used by DAC channels ############################*/
   
4.    __IO uint32_t wait_loop_index = 0;
   
5.   /* Enable GPIO Clock */
   
6.   LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOA);  
   
7.   /* Configure GPIO in analog mode to be used as DAC output */
   
8.   LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_4, LL_GPIO_MODE_ANALOG);
   
9.    /* Configure GPIO in analog mode to be used as DAC output */
   
10.   LL_GPIO_SetPinMode(GPIOA, LL_GPIO_PIN_6, LL_GPIO_MODE_ANALOG);   
    
11.   /*## Configuration of DAC ##################################################*/  
    
12.   /* Enable DAC clock */
    
13.   LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_DAC1);
    
14.   LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_DAC2);  
    
15.   /* Select trigger source */
    
16.   LL_DAC_SetTriggerSource(DAC1, LL_DAC_CHANNEL_1, LL_DAC_TRIG_SOFTWARE);
    
17.   LL_DAC_SetTriggerSource(DAC2, LL_DAC_CHANNEL_1, LL_DAC_TRIG_SOFTWARE);   
    
18.   /* Set the data to be loaded in the data holding register */
    
19.    LL_DAC_ConvertData12RightAligned(DAC1, LL_DAC_CHANNEL_1, 0x300);
    
20.    LL_DAC_ConvertData12RightAligned(DAC2, LL_DAC_CHANNEL_1, 0x300);  
    
21.   /* Enable interruption DAC channel1 underrun */
    
22.   LL_DAC_EnableIT_DMAUDR1(DAC1);
    
23.   LL_DAC_EnableIT_DMAUDR1(DAC2);
    
24.   /* Enable DAC channel */
    
25.   LL_DAC_Enable(DAC1, LL_DAC_CHANNEL_1);
    
26.   LL_DAC_Enable(DAC2, LL_DAC_CHANNEL_1);
    
27.   /* Delay for DAC channel voltage settling time from DAC channel startup.    */
    
28.   wait_loop_index = ((LL_DAC_DELAY_STARTUP_VOLTAGE_SETTLING_US * (SystemCoreClock / (100000 * 2))) / 10);
    
29.   while(wait_loop_index != 0)
    
30.   {
    
31.     wait_loop_index--;
    
32.   }
    
33.   LL_DAC_EnableTrigger(DAC1, LL_DAC_CHANNEL_1);
    
34.   LL_DAC_EnableTrigger(DAC2, LL_DAC_CHANNEL_1);
    
35. }

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调试时观测两路DAC的寄存器，数值都相同，但DAC2管脚上始终没有输出电平，请教各位老师，这个问题怎么查？


仔细阅读了数据手册，发现DAC2与DAC1不同的一点是：DAC2在输出端有一个switch需要配置，配置为switch_enable就可以了。

DAC2可以不输出到引脚。