使用RT-Thread和CPK-RA2L1采集DHT11溫濕度

一、準備
本篇文章主要介紹使用RT-Thread Studio 和瑞薩 CPK-RA2L1評估板，使用大佬的輪子采集溫濕度

二、硬件準備
CPK-RA2L1評估板, 這個板子的芯片型號是 R7FA2L1AB2DFM，DHT11 溫濕度傳感器。

三、新建工程

1、總線空閑狀態為高電平,主機把總線拉低等待DHT11響應,主機把總線拉低必須大于18毫秒,保證DHT11能檢測到起始信號。DHT11接收到主機的開始信號后,等待主機開始信號結束,然后發送80us低電平響應信號.主機發送開始信號結束后,延時等待20-40us后, 讀取DHT11的響應信號,主機發送開始信號后,可以切換到輸入模式,或者輸出高電平均可, 總線由上拉電阻拉高。

2、總線為低電平,說明DHT11發送響應信號,DHT11發送響應信號后,再把總線拉高80us,準備發送數據,每一bit數據都以50us低電平時隙開始,高電平的長短定了數據位是0還是1.格式見下面圖示.如果讀取響應信號為高電平,則DHT11沒有響應,請檢查線路是否連接正常.當最后一bit數據傳送完畢后，DHT11拉低總線50us,隨后總線由上拉電阻拉高進入空閑狀態

3、數字0信號

4、數字1信號

四、驅動代碼

/*

• 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、初始化類型
  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);//將攝氏溫度轉為開氏溫度
float convert_c2f(float c);//將攝氏溫度轉為華氏溫度
float convert_f2c(float f);//將華氏溫度轉為攝氏溫度
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_ */

這里DHT11 使用的是 GPIO 0208,所以需要把這個引腳配置為輸入模式

五、燒錄驗證