Arduino從DHT11讀取溫濕度數據并顯示在1602LCD

硬件清單

Arduino NANO
1602LCD + PCF8574T模塊
YL-47 DHT11模塊

連線

1. 連接LCD: PCF8574T模塊4pin(Gnd, Vcc, SDA i2c數據, SCL i2c時鐘) 連接至Arduino接口 Gnd -> Gnd, Vcc -> Vcc, SDA -> A4, SDL -> A5
2. 連接YL-47 DHT11: Gnd -> Gnd, Vcc -> Vcc, Data-> D4

Library

除了1602需要的庫以外, 需要安裝兩個自帶的庫:? DHT Sensor Library by Adafruit, Adafruit Unified Sensor

測試代碼

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>#define DHTPIN 4
#define DHTTYPE DHT11// I2C地址, 一般為0x3F, 0x20或0x27
LiquidCrystal_I2C lcd(0x27,16,2);
// 初始化DHT
DHT dht(DHTPIN, DHTTYPE);void setup() {lcd.init();lcd.backlight(); // 打開背光Serial.begin(9600);dht.begin();lcd.setCursor(0,0); // line 0, pos 0lcd.print("Good Day!");lcd.setCursor(0,1); // line 1, pos 0lcd.print("H:     % T:");delay(1000);
}void loop() {// Reading temperature or humidity takes about 250 milliseconds!// Sensor readings may also be up to 2 seconds 'old' (its 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);// 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;}// 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);Serial.print("Humidity: ");Serial.print(h);Serial.print(" %\t");Serial.print("Temperature: ");Serial.print(t);Serial.print(" *C ");Serial.print(f);Serial.print(" *F\t");Serial.print("Heat index: ");Serial.print(hic);Serial.print(" *C ");Serial.print(hif);Serial.println(" *F");lcd.setCursor(2,1); // line 1, pos 0
  lcd.print(h);lcd.setCursor(11,1); // line 1, pos 0
  lcd.print(t);delay(1000);
}

?

代碼說明

1. DHT11啟動到讀取數據需要等待1~2秒
2. 溫濕度的精度都為1, 沒有小數部分
3. DHT庫里面帶了計算熱指數的方法 computeHeatIndex(), 用于生成綜合溫濕度計算得到的熱指數值

改進拼接字符串

改進后的代碼, 注意: arduino里的sprintf只能格式化整數, 不能格式化浮點

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <DS3231.h>#define DHTPIN 4
#define DHTTYPE DHT11// I2C地址, 一般為0x3F, 0x20或0x27
LiquidCrystal_I2C lcd(0x27,16,2);
DHT dht(DHTPIN, DHTTYPE);
DS3231 Clock;
bool century=false;
bool h12;
bool PM;void setup() {lcd.init();//lcd.backlight(); // 打開背光Serial.begin(9600);dht.begin();lcd.setCursor(0,0); // line 0, pos 0lcd.print("Good Day Jessie~~");lcd.setCursor(0,1); // line 1, pos 0lcd.print("H:  % T:   T:");delay(1000);
}void loop() {char str[17];sprintf(str,"%02d-%02d %02d:%02d:%02d  ",Clock.getMonth(century),Clock.getDate(),Clock.getHour(h12, PM),Clock.getMinute(),Clock.getSecond());lcd.setCursor(0,0); // line 0, pos 0
  lcd.print(str);// Reading temperature or humidity takes about 250 milliseconds!// Sensor readings may also be up to 2 seconds 'old' (its 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);// 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;}// 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);Serial.print("Humidity: ");Serial.print(h);Serial.print(" %\t");Serial.print("Temperature: ");Serial.print(t);Serial.print(" *C ");Serial.print(f);Serial.print(" *F\t");Serial.print("Heat index: ");Serial.print(hic);Serial.print(" *C ");Serial.print(hif);Serial.println(" *F");lcd.setCursor(2,1); // line 1, pos 0lcd.print((int)h);lcd.setCursor(8,1); // line 1, pos 0lcd.print((int)t);lcd.setCursor(13,1);lcd.print((int)(Clock.getTemperature()*10));delay(1000);
}

?