使用RT-Thread和CPK-RA2L1采集DHT11温湿度

冬至子 2023-10-11 1285

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描述

一、准备
本篇文章主要介绍使用RT-Thread Studio 和瑞萨 CPK-RA2L1评估板，使用大佬的轮子采集温湿度

二、硬件准备
CPK-RA2L1评估板, 这个板子的芯片型号是 R7FA2L1AB2DFM，DHT11 温湿度传感器。

DHT11

三、新建工程

1、总线空闲状态为高电平,主机把总线拉低等待DHT11响应,主机把总线拉低必须大于18毫秒,保证DHT11能检测到起始信号。DHT11接收到主机的开始信号后,等待主机开始信号结束,然后发送80us低电平响应信号.主机发送开始信号结束后,延时等待20-40us后, 读取DHT11的响应信号,主机发送开始信号后,可以切换到输入模式,或者输出高电平均可, 总线由上拉电阻拉高。

DHT11

2、总线为低电平,说明DHT11发送响应信号,DHT11发送响应信号后,再把总线拉高80us,准备发送数据,每一bit数据都以50us低电平时隙开始,高电平的长短定了数据位是0还是1.格式见下面图示.如果读取响应信号为高电平,则DHT11没有响应,请检查线路是否连接正常.当最后一bit数据传送完毕后，DHT11拉低总线50us,随后总线由上拉电阻拉高进入空闲状态

DHT11

3、数字0信号

DHT11

4、数字1信号

DHT11

四、驱动代码

/*

  • Copyright (c) 2006-2021, RT-Thread Development Team
  • SPDX-License-Identifier: Apache-2.0
  • Change Logs:
  • Date Author Notes
  • 2023-03-01 DYC the first version
    /
    #include "dht11.h"
    #include
    #include "hal_data.h"
    #include
    #define DBG_TAG "sensor.asair.dhtxx"
    #ifdef PKG_USING_DHTXX_DEBUG
    #define DBG_LVL DBG_LOG
    #else
    #define DBG_LVL DBG_ERROR
    #endif
    #include
    /     timing /
    #define DHT1x_BEGIN_TIME 20 /     ms /
    #define DHT2x_BEGIN_TIME 1 /     ms /
    #define DHTxx_PULL_TIME 30 /     us /
    #define DHTxx_REPLY_TIME 100 /     us /
    #define MEASURE_TIME 40 /     us /
    RT_WEAK void rt_hw_us_delay(rt_uint32_t us)
    {
    rt_uint32_t delta;
    us = us * (SysTick->LOAD / (1000000 / RT_TICK_PER_SECOND));
    delta = SysTick->VAL;
    while (delta - SysTick->VAL < us) continue;
    }
    /     *
  • This function will split a number into two part according to times.
  • @param num the number will be split
  • @param integer the integer part
  • @param decimal the decimal part
  • @param times how many times of the real number (you should use 10 in this case)
  • @return 0 if num is positive, 1 if num is negative
    */
    int split_int(const int num, int *integer, int *decimal, const rt_uint32_t times)
    {
    int flag = 0;
    if (num < 0) flag = 1;
    int anum = num<0 ? -num : num;
    integer = anum / times;
    decimal = anum % times;
    return flag;
    }
    /
  • This function will convert temperature in degree Celsius to Kelvin.
  • @param c the temperature indicated by degree Celsius
  • @return the result
    /
    float convert_c2k(float c)
    {
    return c + 273.15;
    }
    /     *
  • This function will convert temperature in degree Celsius to Fahrenheit.
  • @param c the temperature indicated by degree Celsius
  • @return the result
    /
    float convert_c2f(float c)
    {
    return c * 1.8 + 32;
    }
    /     *
  • This function will convert temperature in degree Fahrenheit to Celsius.
  • @param f the temperature indicated by degree Fahrenheit
  • @return the result
    /
    float convert_f2c(float f)
    {
    return (f - 32) * 0.55555;
    }
    /     *
  • This function will read a bit from sensor.
  • @param pin the pin of Dout
  • @return the bit value
    /
    static uint8_t dht_read_bit(const rt_base_t pin)
    {
    uint8_t retry = 0;
    while(rt_pin_read(pin) && retry < DHTxx_REPLY_TIME)
    {
    retry++;
    rt_hw_us_delay(1);
    }
    retry = 0;
    while(!rt_pin_read(pin) && retry < DHTxx_REPLY_TIME)
    {
    retry++;
    rt_hw_us_delay(1);
    }
    rt_hw_us_delay(MEASURE_TIME);
    return rt_pin_read(pin);
    }
    /     *
  • This function will read a byte from sensor.
  • @param pin the pin of Dout
  • @return the byte
    */
    static uint8_t dht_read_byte(const rt_base_t pin)
    {
    uint8_t i, byte = 0;
    for(i=0; i<8; i++)
    {
    byte <<= 1;
    byte |= dht_read_bit(pin);
    }
    return byte;
    }
    /**
  • This function will read and update data array.
  • @param dev the device to be operated
  • @return RT_TRUE if read successfully, otherwise return RT_FALSE.
    /
    rt_bool_t dht_read(dht_device_t dev)
    {
    RT_ASSERT(dev);
    uint8_t i, retry = 0, sum = 0;
    #ifdef PKG_USING_DHTXX_INTERRUPT_DISABLE
    rt_base_t level;
    #endif
    /     Reset data buffer /
    rt_memset(dev->data, 0, DHT_DATA_SIZE);
    /     MCU request sampling /
    rt_pin_mode(dev->pin, PIN_MODE_OUTPUT);
    rt_pin_write(dev->pin, PIN_LOW);
    if (dev->type == DHT11) {
    rt_thread_mdelay(DHT1x_BEGIN_TIME); /     Tbe /
    } else {
    rt_thread_mdelay(DHT2x_BEGIN_TIME);
    }
    #ifdef PKG_USING_DHTXX_INTERRUPT_DISABLE
    level = rt_hw_interrupt_disable();
    #endif
    rt_pin_mode(dev->pin, PIN_MODE_INPUT_PULLUP);
    rt_hw_us_delay(DHTxx_PULL_TIME); /     Tgo /
    /     Waiting for sensor reply /
    while (rt_pin_read(dev->pin) && retry < DHTxx_REPLY_TIME)
    {
    retry++;
    rt_hw_us_delay(1); /     Trel /
    }
    if(retry >= DHTxx_REPLY_TIME) return RT_FALSE;
    retry = 0;
    while (!rt_pin_read(dev->pin) && retry < DHTxx_REPLY_TIME)
    {
    retry++;
    rt_hw_us_delay(1); /     Treh /
    };
    if(retry >= DHTxx_REPLY_TIME) return RT_FALSE;
    /     Read data /
    for(i=0; i {
    dev->data[i] = dht_read_byte(dev->pin);
    }
    #ifdef PKG_USING_DHTXX_INTERRUPT_DISABLE
    rt_hw_interrupt_enable(level);
    #endif
    /     Checksum */
    for(i=0; i {
    sum += dev->data[i];
    }
    if(sum != dev->data[4]) return RT_FALSE;
    return RT_TRUE;
    }
    /**
  • This function will get the humidity from dhtxx sensor.
  • @param dev the device to be operated
  • @return the humidity value
    /
    rt_int32_t dht_get_humidity(dht_device_t const dev)
    {
    RT_ASSERT(dev);
    rt_int32_t humi = 0;
    switch(dev->type)
    {
    case DHT11:
    humi = dev->data[0] * 10 + dev->data[1];
    break;
    default:
    break;
    }
    return humi;
    }
    /     *
  • This function will get the temperature from dhtxx sensor.
  • @param dev the device to be operated
  • @return the temperature value
    /
    rt_int32_t dht_get_temperature(dht_device_t const dev)
    {
    RT_ASSERT(dev);
    rt_int32_t temp = 0;
    switch(dev->type)
    {
    case DHT11:
    temp = dev->data[2] * 10 + (dev->data[3] & 0x7f);
    if(dev->data[3] & 0x80) {
    temp = -temp;
    }
    break;
    default:
    break;
    }
    return temp;
    }
    /     *
  • This function will init dhtxx sensor device.
  • @param dev the device to init
  • @param pin the pin of Dout
  • @return the device handler
    */
    rt_err_t dht_init(struct dht_device dev, const rt_base_t pin)
    {
    if(dev == NULL)
    return -RT_ERROR;
    dev->type = DHT_TYPE;
    dev->pin = pin;
    rt_memset(dev->data, 0, DHT_DATA_SIZE);
    rt_pin_mode(dev->pin, PIN_MODE_INPUT_PULLUP);
    return RT_EOK;
    }
    // 1、初始化类型
    dht_device_t dht_create(const rt_base_t pin)
    {
    dht_device_t dev;
    dev = rt_calloc(1, sizeof(struct dht_device));
    if (dev == RT_NULL)
    {
    LOG_E("Can't allocate memory for dhtxx device");
    return RT_NULL;
    }
    dev->type = DHT_TYPE;
    dev->pin = pin;
    rt_memset(dev->data, 0, DHT_DATA_SIZE);
    rt_pin_mode(dev->pin, PIN_MODE_INPUT_PULLUP);
    return dev;
    }
    void dht_delete(dht_device_t dev)
    {
    if (dev)
    rt_free(dev);
    }
    /
    Copyright (c) 2006-2021, RT-Thread Development Team

SPDX-License-Identifier: Apache-2.0

Change Logs:
Date Author Notes
2023-03-01 DYC the first version
/
#ifndef SRC_DHT11_H_
#define SRC_DHT11_H_
#include
#include
#include
#include
#include
#define DHTLIB_VERSION "0.9.0"
#define DHT_DATA_SIZE 5
/ sensor model type */
#define DHT11 0
#define DHT_TYPE DHT11
struct dht_device
{
rt_base_t pin;
rt_uint8_t type;
rt_uint8_t data[DHT_DATA_SIZE];
rt_mutex_t lock;
};
typedef struct dht_device *dht_device_t;
dht_device_t dht_create(const rt_base_t pin);
void dht_delete(dht_device_t dev);
rt_err_t dht_init(struct dht_device *dev, const rt_base_t pin);
rt_bool_t dht_read(dht_device_t dev);
rt_int32_t dht_get_humidity(dht_device_t dev);
rt_int32_t dht_get_temperature(dht_device_t dev);
float convert_c2k(float c);//将摄氏温度转为开氏温度
float convert_c2f(float c);//将摄氏温度转为华氏温度
float convert_f2c(float f);//将华氏温度转为摄氏温度
rt_int32_t split_int(const rt_int32_t num, rt_int32_t *integer,
rt_int32_t *decimal, const rt_uint32_t times);
rt_err_t rt_hw_dht_init(const char *name, struct rt_sensor_config cfg);
#endif / SRC_DHT11_H_ */

这里DHT11 使用的是 GPIO 0208,所以需要把这个引脚配置为输入模式

DHT11

五、烧录验证

DHT11

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