Tafuta Msimbo

Kodi ya Arduino na Video kwa Sensor ya Joto na Unyevu DHT22

Kodi ya Arduino na Video kwa Sensor ya Joto na Unyevu DHT22

Katika mafunzo haya, tutajifunza jinsi ya kutumia kihisi cha joto na unyevu cha DHT22 pamoja na Arduino. DHT22, inayojulikana pia kama AM2302, ina uwezo wa kupima joto kutoka -40 hadi 80 digrii Selsiasi na unyevu kutoka asilimia 0 hadi 99. Kwa kufuata mwongozo huu, utaweza kuonyesha joto kwa Selsiasi, Farenheiti, au Kelvin, pamoja na kiwango cha unyevu.

DHT22 sensor with PCB-1

Tutatumia maktaba ya kihisi cha DHT kusoma data kutoka kwenye kihisi kwa urahisi. Maktaba hii hurahisisha mchakato wa kuwasiliana na DHT22 na inaturuhusu kupata thamani za joto na unyevu kwa mistari michache tu ya msimbo. Kwa maelezo ya kina zaidi, nakuhimiza utazame video inayohusiana (katika video saa 00:00).

Vifaa Vimeelezwa

Sehemu kuu katika mradi huu ni moduli ya kihisi cha DHT22, ambayo ni kihisi cha dijitali cha joto na unyevu. Inatumia kipengele cha capacitive cha kupima unyevu na thermistor kupima hewa inayozunguka. Pato ni ishara ya dijitali inayoweza kusomwa na Arduino.

DHT22 hufanya kazi kwa voltage kati ya 3.3 hadi 5 volti na huwasiliana kupitia interface ya waya moja, na kuifanya iwe rahisi kuiunganisha katika miradi yako. Pia ina umbali mrefu wa usambazaji wa hadi mita 20, ikiruhusu kubadilika katika uwekaji wa kihisi.

Maelezo ya Datasheet

MtengenezajiAosong
Nambari ya sehemuDHT22 (AM2302)
Voltage ya Logic/IO3.3 - 5 V
Voltage ya usambazaji3.3 - 5 V
Kiwango cha kupima (Joto)-40 hadi +80 °C
Kiwango cha kupima (Unyevu)0 hadi 99 %
Usahihi (Joto)±0.5 °C
Usahihi (Unyevu)±2 % kwa 25 °C
Azimio0.1 °C / 0.1 %
Umbali wa usambazajihadi mita 20
KifurushiModuli ya pini 4

  • Hakikisha usambazaji wa nishati sahihi kati ya 3.3V na 5V.
  • Tumia resistor ya kuvuta-juu ya 10K kati ya pini ya data na nishati.
  • Weka waya za kihisi fupi kwa usomaji sahihi.
  • Epuka kupiga mara kwa mara; ruhusu muda kati ya usomaji.
  • Kuwa makini na mambo ya mazingira yanayoathiri usomaji.

Maagizo ya Uunganishaji

Arduino wiring for DHT22 sensor
Arduino wiring for DHT22 sensor

Ili kuunganisha kihisi cha DHT22, anza kwa kuunganisha pini ya nishati (pini 1) ya kihisi kwenye pato la 5V kwenye Arduino. Ifuatayo, unganisha pini ya ardhi (pini 4) kwenye moja ya pini za GND kwenye Arduino. Pini ya data (pini 2) inapaswa kuunganishwa kwenye pini ya dijitali 2 kwenye Arduino kwa mawasiliano. Zaidi ya hayo, weka resistor ya 10K kati ya pini ya data na pini ya nishati ili kuhakikisha usomaji thabiti.

Ikiwa unatumia pini tofauti kwa data, kumbuka kusasisha msimbo ipasavyo kwa kubadilisha thamani ya #define DHTPIN ili ilingane na pini iliyochaguliwa. Usanidi unapaswa kuwa rahisi, kufuata viunganisho hivi kutahakikisha kihisi chako kinafanya kazi kwa usahihi.

Mifano ya Msimbo na Maelezo

Msimbo ufuatao huanzisha kihisi cha DHT22 na kusoma thamani za joto na unyevu. Kwanza, tunajumuisha maktaba ya DHT na kufafanua pini ambayo kihisi kimeunganishwa:

#include "DHT.h"
#define DHTPIN 2     // pini ya dijitali ambayo tumeunganisha
#define DHTTYPE DHT22   // DHT 22  (AM2302)
DHT dht(DHTPIN, DHTTYPE);

Hapa, kigezo DHTPIN kimewekwa kuwa 2, kinachoonyesha kwamba pini ya data ya kihisi imeunganishwa kwenye pini ya dijitali 2 ya Arduino. DHTTYPE inafafanua aina ya kihisi kinachotumika, ambacho katika kesi hii ni DHT22.

Ifuatayo, katika kazi ya setup(), tunaanzisha kihisi na serial monitor:

void setup() {
  Serial.begin(9600);
  dht.begin();
}

Kipande hiki cha msimbo huanzisha mawasiliano ya serial na kuandaa kihisi cha DHT kwa usomaji. Serial.begin(9600) huweka kiwango cha baud kwa mawasiliano ya serial.

Katika kazi ya loop(), tunaweza kusoma na kuonyesha thamani za joto na unyevu:

Serial.print("Joto: ");
Serial.print(getTemp("c")); // Selsiasi
Serial.print(" *C ");
Serial.print(getTemp("h")); // Unyevu
Serial.println(" % ");

Sehemu hii ya msimbo huchapisha joto kwa Selsiasi na asilimia ya unyevu kwenye serial monitor. Kazi ya getTemp() inatumika kupata data inayohitajika kulingana na kigezo kilichopitishwa.

Maonyesho / Nini cha Kutarajia

Mara tu kila kitu kimewekwa na msimbo umepakiwa, unapaswa kuona usomaji wa joto na unyevu ukionyeshwa kwenye serial monitor. DHT22 inaweza kuchukua muda kutulia, hivyo hakikisha unaruhusu sekunde chache kati ya usomaji (katika video saa 15:00). Ikiwa kuna matatizo yoyote na usomaji, angalia uunganishaji wako na uhakikishe viunganisho viko salama. Makosa ya kawaida ni pamoja na ugawaji usio sahihi wa pini au matatizo ya usambazaji wa nishati.

Vidokezo vya Muda kwenye Video

  • 00:00 - Utangulizi wa Kihisi cha DHT22
  • 01:30 - Kuunganisha Kihisi
  • 03:00 - Maelezo ya Msimbo
  • 04:30 - Maonyesho ya Msimbo
  • 06:00 - Hitimisho

Bilder

Arduino wiring for DHT22 sensor
Arduino wiring for DHT22 sensor
DHT22 sensor with PCB-1
DHT22 sensor with PCB-1
DHT22 with PCB red
DHT22 with PCB red
DHT22 sensor no PCB
DHT22 sensor no PCB
54-Arduion code DHT22 Temperature and Humidity Sensor Module
Språk: C++
++
/*
 * This is the Arduino code for the DHT22 module to read temperature and humidity.
 * This code can display temperature in:
 * getTemp("c") is used to get Celsius.
 * getTemp("f") is used to get Fahrenheit.
 * getTemp("k") is used for Kelvin.
 * getTemp("hif") is used to get Fahrenheit.
 * getTemp("hic") is used to get Celsius.
 * getTemp("h") is used to get humidity.
 * Watch the video https://youtu.be/oi_GPSLjgBY
 * Other Arduino library and videos https://robojax.com
 * 
 * Written/updated by Ahmad Shamshiri for Robojax.com Video
 * Date: Jan 08, 2018, in Ajax, Ontario, Canada
 * Permission granted to share this code given that this
 * note is kept with the code.
 * Disclaimer: This code is "AS IS" and for educational purposes only.
 * 
 * original source code : https://github.com/adafruit/DHT-sensor-library
 */

// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain


#include "DHT.h"

#define DHTPIN 2     // what digital pin we're connected to

// Uncomment whatever type you're using!
//#define DHTTYPE DHT11   // DHT 11
#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster processors.
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  Serial.println("DHTxx Robojax test!");

  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);


  // Robojax.com test video
  Serial.print("Temperature: ");
  
  Serial.print(getTemp("c"));
  
  Serial.print(" *C ");
  Serial.print(getTemp("f"));
  Serial.println (" *F");
  Serial.println("-----------------");  
  Serial.print("Heat index: ");
  Serial.print(getTemp("hic"));
  Serial.print(" *C ");
  Serial.print(getTemp("hif"));
  Serial.println(" *F");
  Serial.print(getTemp("k"));
  Serial.println(" *K");
  Serial.println("-----------------");    
  Serial.print("Humidity: ");
  Serial.print(getTemp("h"));
  Serial.println(" % ");
  Serial.println("===========================");
}


/*
 * getTemp(String req)
 * returns the temperature related parameters
 * req is string request
 * This code can display temperature in:
 * getTemp("c") is used to get Celsius.
 * getTemp("f") is used to get Fahrenheit.
 * getTemp("k") is used for Kelvin.
 * getTemp("hif") is used to get Fahrenheit.
 * getTemp("hic") is used to get Celsius.
 * getTemp("h") is used to get humidity.
 */
float getTemp(String req)
{

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor).
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);

  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return 0.0;
  }
  // Compute heat index in Kelvin 
  float k = t + 273.15;
  if(req =="c"){
    return t;//return Celsius
  }else if(req =="f"){
    return f;// return Fahrenheit
  }else if(req =="h"){
    return h;// return humidity
  }else if(req =="hif"){
    return hif;// return heat index in Fahrenheit
  }else if(req =="hic"){
    return hic;// return heat index in Celsius
  }else if(req =="k"){
    return k;// return temperature in Kelvin
  }else{
    return 0.000;// if no request found, return 0.000
  }
 
}

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