[Bug] stm32_adc_get_vref ()接口返回的是dc->Instance->DR并不是参考电压，导致rt_adc_voltage无法正常计算出采集的电压

RT-Thread Version

master

Hardware Type/Architectures

stm32f4x

Develop Toolchain

GCC

Describe the bug

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

static rt_adc_device_t dev_;

rt_uint16_t bat_v;
rt_int16_t v;

static void thread_(void *param)
{
    while (1)
    {
        v = rt_adc_voltage(dev_, 8);
        bat_v = v / 10 * 110;
        rt_kprintf("rt_adc_voltage: %d\n", v);
        rt_kprintf("bat_v: %d(mV)\n", bat_v);
        rt_thread_mdelay(1000);
    }
}

void app_battery_init(void)
{
    rt_err_t ret;
    dev_ = (rt_adc_device_t)rt_device_find("adc2");
    if (!dev_)
        goto exit;

    ret = rt_adc_enable(dev_, 8);
    rt_kprintf("rt_adc_enable ret: %d\n", ret);

    rt_thread_t t = rt_thread_create("bat_thread", thread_, RT_NULL, 2048, 25, 20);
    if (!t)
        goto exit;

    rt_thread_startup(t);

    return;
exit:
    rt_kprintf("error\n");
    return;
}

Other additional context

No response

Start by locating the STM32 implementation of stm32_adc_get_vref() and the rt_adc_voltage() path used by the stm32f4x ADC2 channel 8 example. Check whether the value returned as the reference voltage is actually the ADC data register value, then reproduce the calculation with the provided application and confirm that rt_adc_voltage reports the expected sampled voltage.