仿照官方例程的程序，无法输出波形

Along

#include "delay.h"
#include "sys.h"
#include "usart.h"  

//ALIENTEK战舰STM32开发板实验19
//DAC 实验  
//技术支持：www.openedv.com
//广州市星翼电子科技有限公司  
/*DAC_InitTypeDef DAC_InitType;
TIM_TimeBaseInitTypeDef    TIM_TimeBaseStructure;
GPIO_InitTypeDef GPIO_InitStructure;  */

void GPIO_Config(void);
void TIM2_Config(void);
void DAC_Config(void);
int main(void)
 {  
delay_init();     //延时函数初始化  
NVIC_Configuration(); //设置NVIC中断分组2:2位抢占优先级，2位响应优先级
uart_init(9600); //串口初始化为9600
SystemInit();
  GPIO_Config();
  TIM2_Config();
  DAC_Config();
while(1)
{
}
 }
void TIM2_Config(void)
{
 TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 , ENABLE);   
    TIM_TimeBaseStructure.TIM_Period =0x0f;    
    TIM_TimeBaseStructure.TIM_Prescaler = 0x0f;    
    TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;    
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; 
    TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);

  TIM_ARRPreloadConfig(TIM2 , ENABLE);

    TIM_SelectOutputTrigger(TIM2 , TIM_TRGOSource_Update);
   TIM_Cmd(TIM2, ENABLE);
}
void DAC_Config(void)
{
   DAC_InitTypeDef DAC_InitStructure;

   RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC , ENABLE);

   DAC_InitStructure.DAC_Trigger = DAC_Trigger_T2_TRGO;
   DAC_InitStructure.DAC_WaveGeneration =DAC_WaveGeneration_Triangle ;  //DAC_WaveGeneration_None
   DAC_InitStructure.DAC_WaveGeneration=DAC_TriangleAmplitude_2047;
   DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
   DAC_Init(DAC_Channel_1, &DAC_InitStructure);
    DAC_Cmd(DAC_Channel_1, ENABLE);  //使能DAC1
}
void GPIO_Config(void)
{
   GPIO_InitTypeDef GPIO_InitStructure;
  
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA , ENABLE); 

 
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 ;
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN; 
   GPIO_Init(GPIOA, &GPIO_InitStructure);       
}

用DAC的一个通道输出三角波，为什么没有波形输出？

正点原子

输出固定电压正常了么