Arduino下读取DHT22温湿度（不使用第三方库）

victor

#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[5] = {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[idx] |= (1 << cnt);
    if (cnt == 0)   // next byte?
    {
      cnt = 7;    // restart at MSB
      idx++;      // next byte!
    }
    else cnt--;
  }

  sum = bits[0]+bits[1]+bits[2]+bits[3];
  if(bits[4] != sum) return DHT_ERR_CHECK;


  humidity = (float)((bits[0] << 8)+bits[1])/10;
  temperature = (float)((bits[2] << 8)+bits[3])/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

1. #include <inttypes.h>
   
2. /*
   
3. * LED
   
4. */
   
5. unsigned int LED = 13;
   
6. /*
   
7. * DHT22配置程序
   
8. */
   
9. unsigned int DHT_PIN = 7;
   
10. 
    
11. #define DHT_OK      1
    
12. #define DHT_ERR_CHECK 0
    
13. #define DHT_ERR_TIMEOUT -1
    
14. float humidity;
    
15. float temperature;
    
16. unsigned char DHT_read()
    
17. {
    
18.   // BUFFER TO RECEIVE
    
19.   unsigned char bits[5] = {0,0,0,0,0};
    
20.   unsigned char cnt = 7;
    
21.   unsigned char idx = 0;
    
22.   unsigned char sum;
    
23. 
    
24. 
    
25.   // REQUEST SAMPLE
    
26.   pinMode(DHT_PIN, OUTPUT);
    
27.   digitalWrite(DHT_PIN, LOW);
    
28.   delay(18);
    
29.   digitalWrite(DHT_PIN, HIGH);
    
30.   delayMicroseconds(40);
    
31.   pinMode(DHT_PIN, INPUT);
    
32. 
    
33.   // ACKNOWLEDGE or TIMEOUT
    
34.   unsigned int count = 10000;
    
35.   while(digitalRead(DHT_PIN) == LOW)
    
36.     if (count-- == 0) return DHT_ERR_TIMEOUT;
    
37. 
    
38.   count = 10000;
    
39.   while(digitalRead(DHT_PIN) == HIGH)
    
40.     if (count-- == 0) return DHT_ERR_TIMEOUT;
    
41. 
    
42.   // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT
    
43.   for (int i=0; i<40; i++)
    
44.   {
    
45.     count = 10000;
    
46.     while(digitalRead(DHT_PIN) == LOW)
    
47.       if (count-- == 0) return DHT_ERR_TIMEOUT;
    
48. 
    
49.     unsigned long t = micros();
    
50. 
    
51.     count = 10000;
    
52.     while(digitalRead(DHT_PIN) == HIGH)
    
53.       if (count-- == 0) return DHT_ERR_TIMEOUT;
    
54. 
    
55.     if ((micros() - t) > 40) bits[idx] |= (1 << cnt);
    
56.     if (cnt == 0)   // next byte?
    
57.     {
    
58.       cnt = 7;    // restart at MSB
    
59.       idx++;      // next byte!
    
60.     }
    
61.     else cnt--;
    
62.   }
    
63. 
    
64.   sum = bits[0]+bits[1]+bits[2]+bits[3];
    
65.   if(bits[4] != sum) return DHT_ERR_CHECK;
    
66.    
    
67. 
    
68.   humidity = (float)((bits[0] << 8)+bits[1])/10;
    
69.   temperature = (float)((bits[2] << 8)+bits[3])/10;
    
70.   
    
71.   return DHT_OK;
    
72. }
    
73. 
    
74. void setup() {
    
75.    pinMode(13,OUTPUT);//指示灯
    
76.    pinMode(DHT_PIN,INPUT);
    
77.    digitalWrite(DHT_PIN, HIGH);
    
78. }
    
79. void loop() {
    
80.    DHT_read();
    
81.    Serial.print("temperature:");
    
82.    Serial.println(temperature);
    
83.    Serial.println("============end===============");
    
84.    delay(1000);
    
85.    digitalWrite(LED,HIGH);
    
86.    delay(925); //Delay
    
87.    digitalWrite(LED,LOW);
    
88.    delay(925); //Delay
    
89. }

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