1.Introduction
Currently, with the continuous development of science and technology, all daily activities are automated, robots gradually take over many positions in our daily lives. In order for automation devices to work correctly and efficiently, sensors are one of the important components. Temperature and humidity are two important factors that need to be collected for analysis and control.
In this tutorial, I will explain its working, pinout, protocol and interfacing with other microcontrollers in detail. I will also post some tutorial links where I have interfaced DHT11 with other microcontrollers. If you have any queries about it, ask in the comments and I will resolve it.
2.SENSOR-MODULE/EXPANSION BOARD PINOUT DIAGRAM
2.1. Hardware Introduction
2.1.1. Arduino UNO R3
Arduino Uno is a microcontroller board based on the ATmega328P (datasheet). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. You can tinker with your Uno without worrying too much about doing something wrong, worst case scenario you can replace the chip for a few dollars and start over again.
“Uno” means one in Italian and was chosen to mark the release of Arduino Software (IDE) 1.0. The Uno board and version 1.0 of Arduino Software (IDE) were the reference versions of Arduino, now evolved to newer releases. The Uno board is the first in a series of USB Arduino boards, and the reference model for the Arduino platform; for an extensive list of current, past or outdated boards see the Arduino index of boards.
Features
ATMega328P Processor
●Memory
+ AVR CPU at up to 16 MHz + 32KB Flash + 2KB SRAM + 1KB EEPROM●Security
+ Power On Reset (POR) + Brown Out Detection (BOD)●Peripherals
+ 2x 8-bit Timer/Counter with a dedicated period register and compare channels + 1x 16-bit Timer/Counter with a dedicated period register, input capture and compare channels + 1x USART with fractional baud rate generator and start-of-frame detection + 1x controller/peripheral Serial Peripheral Interface (SPI) + 1x Dual mode controller/peripheral I2C + 1x Analog Comparator (AC) with a scalable reference input + Watchdog Timer with separate on-chip oscillator + Six PWM channels + Interrupt and wake-up on pin change●Power
+ 2.7-5.5 volts
2.1.2 DHT11
DHT11 output calibrated digital signal. It applies exclusive digital-signal-collecting-technique and humidity sensing technology, assuring its reliability and stability. Its sensing elements is connected with 8-bit single-chip computer.
Every sensor of this model is temperature compensated and calibrated in accurate calibration chamber and the calibration-coefficient is saved in type of programmer in OTP memory, when the sensor is detecting, it will cite coefficient from memory.
Small size & low consumption & long transmission distance(100m) enable DHT11 to be suited in all kinds of harsh application occasions. Single-row packaged with four pins, making the connection very convenient.
●Operating specifications:
Power and Pins : Power’s voltage should be 3.3-5.5V DC. When power is supplied to the sensor, don’t send any instruction to the sensor within one second to pass unstable status. One capacitor valued 100nF can be added between VDD and GND for wave filtering. Communication and signal: 1-wire bus is used for communication between MCU and DHT11.DHT11.
2.1.3.LCD16x2 – I2C
Features of LCD16x2:
+ The operating voltage of this LCD is 4.7V-5.3V
+ It includes two rows where each row can produce 16-characters.
+ The utilization of current is 1mA with no backlight
+ Every character can be built with a 5×8 pixel box
+ The alphanumeric LCDs alphabets & numbers
+ Is display can work on two modes like 4-bit & 8-bit
+ These are obtainable in Blue & Green Backlight
+ It displays a few custom generated characters
I2C Serial Interface Adapter
2.2. How to connect
Source code:
#include <Arduino.h>
#include <DHT.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2);
const int DHTPIN = 4;
const int DHTTYPE = DHT11;
DHT dht(DHTPIN, DHTTYPE);
byte degree[8] = {
0B01110,
0B01010,
0B01110,
0B00000,
0B00000,
0B00000,
0B00000,
0B00000
};
void setup() {
lcd.init();
lcd.backlight();
lcd.print(“Temper: “);
lcd.setCursor(0,1);
lcd.print(“Humidity: “);
lcd.createChar(1, degree);
dht.begin();
}
void loop()
{
float h = dht.readHumidity();
float t = dht.readTemperature();
if (isnan(t) || isnan(h))
{
}
else
{
lcd.setCursor(10,0);
lcd.print(round(t));
lcd.print(” “);
lcd.write(1);
lcd.print(“C”);
lcd.setCursor(10,1);
lcd.print(round(h));
lcd.print(” %”);
}
}
