为什么dac设置PA4输出高

时光……记忆

void Dac1_Init(void)
{
GPIO_InitTypeDef  GPIO_InitStructure;
DAC_InitTypeDef   DAC_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);   
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);    

GPIO_InitStructure.GPIO_Pin=GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AIN;
GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_SetBits(GPIOA, GPIO_Pin_4);//为什么设置高电平


DAC_InitStructure.DAC_Trigger=DAC_Trigger_None;
DAC_InitStructure.DAC_WaveGeneration=DAC_WaveGeneration_None;
DAC_InitStructure.DAC_OutputBuffer=DAC_OutputBuffer_Disable;
DAC_InitStructure.DAC_LFSRUnmask_TriangleAmplitude=DAC_LFSRUnmask_Bit0;
DAC_Init(DAC_Channel_1,&DAC_InitStructure);

DAC_Cmd(DAC_Channel_1,ENABLE);
DAC_SetChannel1Data(DAC_Align_12b_R, 0);

}

正点原子

没用的，你去掉都不影响。