stm32g431，ADC转换成电压值，为什么手动旋转R37，显示的电压值总是整数式变化（例如1.00V，2.00V，3.00V）

main.c 中的while循环部分：

while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
        
            adc=getADC(&hadc2);
            Work();

hadc.c

#include "hadc.h"


double getADC(ADC_HandleTypeDef *pin)
{
    unsigned int adc;
    HAL_ADC_Start(pin);
    adc=HAL_ADC_GetValue(pin);
    return adc*3.3/4096;

}

myfile.c

#include "myfile.h"
#include "led.h"
#include "lcd.h"
#include "key.h"
#include "main.h"
#include "stdio.h"
#include "adc.h"
#include "hadc.h"
#include "tim.h"

extern uint menu_mode;    //运行模式标志  0--自动模式    1--手动模式
extern uint signal;        //确定按下哪个按键    例如：signal=0  表示B1键  signal=1  表示B2键
extern uint view_chart;  //显示界面标志  0--数据界面    1--参数界面
extern uint pa6_duty,pa7_duty ;  //占空比
char text1[30];

extern uint adc;    //保存转换的电压值

//数据界面显示
void data_menu_show(double v,uint menu_mode)
{
    //显示运行模式---自动模式
    Led_Display(menu_mode);
    //显示数据界面
    LCD_DisplayStringLine(Line0 ,(unsigned char *)"      Data          ");
    sprintf(text1,"    V:%.2fV         ",v);
    LCD_DisplayStringLine(Line2 ,(unsigned char *)text1);
    if(menu_mode)
        LCD_DisplayStringLine(Line4 ,(unsigned char *)"    Mode:MXNU       ");
    else
        LCD_DisplayStringLine(Line4 ,(unsigned char *)"    Mode:AUTO       ");
}
//参数界面显示
void para_menu_show(uint pa6_duty,uint pa7_duty)
{
    
    LCD_DisplayStringLine(Line0 ,(unsigned char *)"      Para          ");
    sprintf(text1,"    PA6:%d%%         ",pa6_duty);
    LCD_DisplayStringLine(Line2 ,(unsigned char *)text1);
        sprintf(text1,"    PA7:%d%%         ",pa7_duty);
    LCD_DisplayStringLine(Line4 ,(unsigned char *)text1);
}

void Display()
{
    if(view_chart%2==0)
        data_menu_show(adc,menu_mode);
    else
        para_menu_show(pa6_duty,pa7_duty);
    Led_Display (menu_mode);

}


void Work()
{
    Key_Contr(signal,view_chart,menu_mode);
    Display();    
}