使用板载电位计（USER POT）通过ADC外设通道读取电平值

1 前言

本实验使用了板载电位计（USER POT）通过ADC外设通道读取电平值，可以手动调节电位计查看ADC通道的电平变化。通过本实验可以学习到简单外设的配置，包括rt-thread的外设配置和FSP的外设配置。

2 查看开发板用户手册

查看手册提取出需要注意的关键信息，电位计使用的ADC引脚是 P004，同时需要短接E31（开发板背面）才能连接到MCU。

3 FSP配置ADC

打开FSP，在Pins页找到 P004 引脚，并查看所属的ADC通道为ADC0通道

在Stacks中添加ADC外设，配置ADC0，在Input配置中打开通道4的输入功能

配置完成点击生成代码，此步必须操作否则配置不会添加到工程中。

4 打开ADC设备驱动

在 RT-Thread settings 中打开 ADC0，保存配置。

5 测试验证

添加测试代码到 hal_entry.c

#define ADC_DEV_NAME "adc0"

#define ADC_DEV_CHANNEL 4

#define REFER_VOLTAGE 330

#define CONVERT_BITS (1 << 12)

static void sensor_read_data(void)

{

rt_adc_device_t adc_dev;

rt_uint32_t value, vol;

rt_err_t ret = RT_EOK;

adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);

if (adc_dev == RT_NULL)

编译下载，输入测试命令 sensor_read_data 查看电位计此时的电平值，可以使用工具旋转电位

计，查看电平变化。

{

rt_kprintf("adc sample run failed! can't find %s device!\n",

ADC_DEV_NAME);

return RT_ERROR;

}

ret = rt_adc_enable(adc_dev, ADC_DEV_CHANNEL);

value = rt_adc_read(adc_dev, ADC_DEV_CHANNEL);

ret = rt_adc_disable(adc_dev, ADC_DEV_CHANNEL);

vol = value * REFER_VOLTAGE / CONVERT_BITS;

rt_kprintf("the voltage is :%d.%02d \n", vol / 100, vol % 100);

}

MSH_CMD_EXPORT(sensor_read_data, sensor_read_data);

hal_entry.c完整代码

/*

• Copyright (c) 2006-2021, RT-Thread Development Team
• SPDX-License-Identifier: Apache-2.0
• Change Logs:
• Date Author Notes
• 2021-10-10 Sherman first version
• 2021-11-03 Sherman Add icu_sample

*/

#include <rtthread.h>

#include "hal_data.h"

#include <rtdevice.h>

#define LED3_PIN BSP_IO_PORT_01_PIN_06

#define USER_INPUT "P105"

void hal_entry(void)

{

rt_kprintf("\nHello RT-Thread!\n");

while (1)

{

    rt_pin_write(LED3_PIN, PIN_HIGH);

    rt_thread_mdelay(500);

    rt_pin_write(LED3_PIN, PIN_LOW);

    rt_thread_mdelay(500);

}

}

void irq_callback_test(void *args)

{

rt_kprintf("\n IRQ00 triggered \n");

}

void icu_sample(void)

{

/* init */

rt_uint32_t pin = rt_pin_get(USER_INPUT);

rt_kprintf("\n pin number : 0x%04X \n", pin);

rt_err_t err = rt_pin_attach_irq(pin, PIN_IRQ_MODE_RISING, irq_callback_test, RT_NULL);

if(RT_EOK != err)

{

    rt_kprintf("\n attach irq failed. \n");

}

err = rt_pin_irq_enable(pin, PIN_IRQ_ENABLE);

if(RT_EOK != err)

{

    rt_kprintf("\n enable irq failed. \n");

}

}

MSH_CMD_EXPORT(icu_sample, icu sample);

#define ADC_DEV_NAME "adc0"

#define ADC_DEV_CHANNEL 4

#define REFER_VOLTAGE 330

#define CONVERT_BITS (1 << 12)

static void sensor_read_data(void)

{

rt_adc_device_t adc_dev;

rt_uint32_t value, vol;

rt_err_t ret = RT_EOK;

adc_dev = (rt_adc_device_t)rt_device_find(ADC_DEV_NAME);

if (adc_dev == RT_NULL)

{

    rt_kprintf("adc sample run failed! can't find %s device!\n",

    ADC_DEV_NAME);

    return RT_ERROR;

}

ret = rt_adc_enable(adc_dev, ADC_DEV_CHANNEL);

value = rt_adc_read(adc_dev, ADC_DEV_CHANNEL);

ret = rt_adc_disable(adc_dev, ADC_DEV_CHANNEL);

vol = value * REFER_VOLTAGE / CONVERT_BITS;

rt_kprintf("the voltage is :%d.%02d \n", vol / 100, vol % 100);

}

MSH_CMD_EXPORT(sensor_read_data, sensor_read_data);

编译下载，输入测试命令 ‘sensor_read_data’ 查看电位计此时的电平值，可以使用工具旋转电位

计，查看电平变化。

C:\Users\Asus>D:/RT-ThreadStudio/plugins/org.rt-thread.studio.serial.putty_1.0.5/putty/plink.exe -serial COM8 -sercfg 115200,8,n,1,N

\ | /

• RT - Thread Operating System

/ | \ 4.1.0 build Aug 15 2022 16:44:58

2006 - 2022 Copyright by RT-Thread team

Hello RT-Thread!

msh >sensor_read_data

the voltage is :1.73

msh >sensor_read_data

the voltage is :1.73

msh >sensor_read_data

the voltage is :1.97

msh >sensor_read_data

the voltage is :0.00

msh >sensor_read_data

the voltage is :0.00

msh >sensor_read_data

the voltage is :3.04

msh >

原作者：2345vor