STM32F103单片机设置DAC固定输出一个电压值，发现电压有规律性的有几十mv波动

发布于 2024-09-01 23:39:49 浏览：389 订阅该版

这个是设置DAC的代码。即使用一个线程定时去设置DAC值，还是会有波动。图形如下
也排除有其它pin对它的干扰。

![微信图片_20240901233733.jpg](https://oss-club.rt-thread.org/uploads/20240901/efbe2321950803e4ec687aafa52bfedb.jpg.webp)
![微信图片_20240901233743.jpg](https://oss-club.rt-thread.org/uploads/20240901/306dd0a49a5017e6923782cab336e3ed.jpg.webp)

#include <rtthread.h>
#include <rtdevice.h>
#include <stdlib.h>

#define DBG_TAG    "dac_sensor"
#define LOG_LVL     DBG_LOG

#include <ulog.h>

#define DAC_DEV_NAME        "dac1"  /* DAC 设备名称 */
#define DAC_DEV_CHANNEL     1       /* DAC 通道 */
#define REFER_VOLTAGE       300         /* 参考电压 3.0V,数据精度乘以100保留2位小数*/
#define CONVERT_BITS        (1 << 12)   /* 转换位数为12位 */

#define THREAD_STACK_SIZE   512
#define THREAD_PRIORITY     20
#define THREAD_TIMESLICE    10
rt_dac_device_t dac_dev;

void dac_set_vol(rt_uint32_t vol,rt_int16_t full_range)
{
    rt_uint32_t value;
    rt_err_t ret = RT_EOK;
    double temp;

temp = 12000;//uA

temp=temp/10000;
    temp=temp*4095/3;
    value=temp;
    if (dac_dev != RT_NULL)
   {
        ret=rt_dac_write(dac_dev, DAC_DEV_CHANNEL, value);
        //LOG_D("rt_dac_write %d value=%d",ret,value);

}

int dac_sensor_out(void)
{
    rt_err_t ret = RT_EOK;

/* 查找设备 */
    dac_dev = (rt_dac_device_t)rt_device_find(DAC_DEV_NAME);
    if (dac_dev == RT_NULL)
    {
        rt_kprintf("can't find %s device!\n", DAC_DEV_NAME);
        return RT_ERROR;
    }
    else
    {
        rt_kprintf("find %s device!\n", DAC_DEV_NAME);
        /* 使能设备 */
         ret = rt_dac_enable(dac_dev, DAC_DEV_CHANNEL);
    }

dac_set_vol(12000,0);

return ret;

}

static void sensor_dac_thread(void *parameter)
{
    dac_sensor_out();
   // while(1)
  //  {

//     dac_set_vol(12000,0);
   //     rt_thread_mdelay(300);
   // }

}
static int sensor_dac_init(void)
{
    rt_thread_t tid;

tid = rt_thread_create("dac out", sensor_dac_thread, RT_NULL, THREAD_STACK_SIZE, THREAD_PRIORITY, THREAD_TIMESLICE);
    if(tid == RT_NULL)
    {
        LOG_E("Fail to create dac out thread");
    }

rt_thread_startup(tid);

return 0;
}
INIT_APP_EXPORT(sensor_dac_init);