论坛 › Arduino DIY › Arduino下读取DHT22温湿度（不使用第三方库）

victor 发表于 2020-3-17 12:39:33

Arduino下读取DHT22温湿度（不使用第三方库）

#include <inttypes.h>
/*
* LED
*/
unsigned int LED = 13;
/*
* DHT22配置程序
*/
unsigned int DHT_PIN = 7;

#define DHT_OK      1
#define DHT_ERR_CHECK 0
#define DHT_ERR_TIMEOUT -1
float humidity;
float temperature;
unsigned char DHT_read()
{
// BUFFER TO RECEIVE
unsigned char bits = {0,0,0,0,0};
unsigned char cnt = 7;
unsigned char idx = 0;
unsigned char sum;


// REQUEST SAMPLE
pinMode(DHT_PIN, OUTPUT);
digitalWrite(DHT_PIN, LOW);
delay(18);
digitalWrite(DHT_PIN, HIGH);
delayMicroseconds(40);
pinMode(DHT_PIN, INPUT);

// ACKNOWLEDGE or TIMEOUT
unsigned int count = 10000;
while(digitalRead(DHT_PIN) == LOW)
    if (count-- == 0) return DHT_ERR_TIMEOUT;

count = 10000;
while(digitalRead(DHT_PIN) == HIGH)
    if (count-- == 0) return DHT_ERR_TIMEOUT;

// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
for (int i=0; i<40; i++)
{
    count = 10000;
    while(digitalRead(DHT_PIN) == LOW)
      if (count-- == 0) return DHT_ERR_TIMEOUT;

    unsigned long t = micros();

    count = 10000;
    while(digitalRead(DHT_PIN) == HIGH)
      if (count-- == 0) return DHT_ERR_TIMEOUT;

    if ((micros() - t) > 40) bits |= (1 << cnt);
    if (cnt == 0)   // next byte?
    {
      cnt = 7;    // restart at MSB
      idx++;      // next byte!
    }
    else cnt--;
}

sum = bits+bits+bits+bits;
if(bits != sum) return DHT_ERR_CHECK;


humidity = (float)((bits << 8)+bits)/10;
temperature = (float)((bits << 8)+bits)/10;

return DHT_OK;
}

void setup() {
   pinMode(13,OUTPUT);//指示灯
   pinMode(DHT_PIN,INPUT);
   digitalWrite(DHT_PIN, HIGH);
}
void loop() {
   DHT_read();
   Serial.print("temperature:");
   Serial.println(temperature);
   Serial.println("============end===============");
   delay(1000);
   digitalWrite(LED,HIGH);
   delay(925); //Delay
   digitalWrite(LED,LOW);
   delay(925); //Delay
}

victor 发表于 2020-3-17 12:39:49

#include <inttypes.h>
/*
* LED
*/
unsigned int LED = 13;
/*
* DHT22配置程序
*/
unsigned int DHT_PIN = 7;

#define DHT_OK      1
#define DHT_ERR_CHECK 0
#define DHT_ERR_TIMEOUT -1
float humidity;
float temperature;
unsigned char DHT_read()
{
// BUFFER TO RECEIVE
unsigned char bits = {0,0,0,0,0};
unsigned char cnt = 7;
unsigned char idx = 0;
unsigned char sum;


// REQUEST SAMPLE
pinMode(DHT_PIN, OUTPUT);
digitalWrite(DHT_PIN, LOW);
delay(18);
digitalWrite(DHT_PIN, HIGH);
delayMicroseconds(40);
pinMode(DHT_PIN, INPUT);

// ACKNOWLEDGE or TIMEOUT
unsigned int count = 10000;
while(digitalRead(DHT_PIN) == LOW)
    if (count-- == 0) return DHT_ERR_TIMEOUT;

count = 10000;
while(digitalRead(DHT_PIN) == HIGH)
    if (count-- == 0) return DHT_ERR_TIMEOUT;

// READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
for (int i=0; i<40; i++)
{
    count = 10000;
    while(digitalRead(DHT_PIN) == LOW)
      if (count-- == 0) return DHT_ERR_TIMEOUT;

    unsigned long t = micros();

    count = 10000;
    while(digitalRead(DHT_PIN) == HIGH)
      if (count-- == 0) return DHT_ERR_TIMEOUT;

    if ((micros() - t) > 40) bits |= (1 << cnt);
    if (cnt == 0)   // next byte?
    {
      cnt = 7;    // restart at MSB
      idx++;      // next byte!
    }
    else cnt--;
}

sum = bits+bits+bits+bits;
if(bits != sum) return DHT_ERR_CHECK;
   

humidity = (float)((bits << 8)+bits)/10;
temperature = (float)((bits << 8)+bits)/10;

return DHT_OK;
}

void setup() {
   pinMode(13,OUTPUT);//指示灯
   pinMode(DHT_PIN,INPUT);
   digitalWrite(DHT_PIN, HIGH);
}
void loop() {
   DHT_read();
   Serial.print("temperature:");
   Serial.println(temperature);
   Serial.println("============end===============");
   delay(1000);
   digitalWrite(LED,HIGH);
   delay(925); //Delay
   digitalWrite(LED,LOW);
   delay(925); //Delay
}

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