electronicguru0007

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Components

	ESP32-WROOM-32E(16MB) Espressif Systems	x 3
	DHT11 Temperature and Relative Humidity Sensor Module	x 1
	Mini Breadboard	x 1
	Bread Board 3.3/5V Power Supply Module	x 1

Tools, APP Software Used etc.

arduino IDE

Arduino

Description

Esp Now Data Sender

What is ESP-Now Protocol?

ESP-NOW is a wireless communication protocol developed by Espressif and capable of packet transmission. This protocol enables multiple devices to easily talk to each other and transfer information optimally between each other. This protocol is similar to the 2.4 GHz wireless connection, often used in wireless mice. Therefore, it is necessary to pair the devices before communicating. This means that the connection is stable after the devices are paired with each other. In other words, if one of your ESPs suddenly shuts down or resets, the connection is established automatically when you restart.

Advantages:

Data transfer up to 250 bytes

Benefit from encrypted communication

It works everywhere. It does not require a router or a DHCP server.

Use Call Back to inform different layers if data transfer is successful or not

Disadvantages:

Maximum limit of 250 payload bytes.

Support for 10 encrypted SoftAPs only

Maximum number of backups in unencrypted mode is 20

WeMOS D1 Wi-Fi Board

WeMOS D1 board is one of the most popular boards used in the field of IoT, one of the advantages of this board compared to boards such as Node MCU is its small size. The Wi-Fi chip used in this board is ESP8266.

Another advantage of this board is the existence of various shields for this board, which makes any project very easy and enjoyable for the user, shields such as battery shield, multi sensor, DHT22, relay, oled, a large number The shield has been developed for this board, which will leave you with a good IoT experience.

DHT11 Sensor

A variety of sensors are designed and manufactured to measure temperature and humidity. Each has a different range and sensitivity. The DHT11 sensor is one of the best sensors for measuring temperature and humidity. These sensors consist of two parts, capacitive humidity and a heat resistor. There is also an analog-to-digital converter unit in the DHT11, which generates digital output. With the help of this converter, the user can use it in microcontrollers to read values.

ESP32 Board

ESP32 is the advanced generation of ESP8266. One of the differences is its built-in Bluetooth capability. It also has a 2.4 GHz Wi-Fi and built-in Bluetooth with 40-nanometer technology from TSMC. This module has the best performance in energy consumption, which helps us to get best results from least energy consumption. If we want to take a closer look at this board is also called System on a chip (SoC) microcontrollers.

Working of this Project

We are using DHT11 sensor to capture the temperature and humidity data. ESP32 board will be the sender and WeMOS D1 mini is the receiver. The ESP32 board will obtain the temperature and humidity values ??and send them to the Wemos board via the ESP-NOW protocol.

Installing Libraries

For this tutorial you need some Libraries in order to make the code working. Go to Sketch -> Include Library -> Manage Libraries. Search for the word “espnow” and install the library.

Now we need to install DHT sensor library and for that we need to type DHT and install it.

Finding MAC Address

Before we learn how to get these MAC addresses, it is better to learn the meaning and concept of MAC addresses and why they exist? Well, if a device is trying to connect to the Internet, it will be assigned with two addresses. First an IP address which is a logical address and then the MAC address, which is the physical address of our device. This MAC address us also know as a fingerprint.

The expansion of MAC is Media Access Control. MAC addresses consist of 48 bits with hexadecimal digits and are found with a structure like this xx: xx: xx: xx: xx: xx. Each xx is equal to 8 bits or one byte. The first 24 bits are specified by the manufacturer of the device and the second 24 bits of devices that can be numbered.

To communicate between ESP32 boards, we need to know the MAC address of other boards. In the process of transferring data or pairing each board, it checks the identity of the other board. Each ESP board has its own MAC address to authenticate. To get this MAC address, upload the following code in your WeMOS D1 mini

#ifdef ESP32

#include <WiFi.h>

#else

#include <ESP8266WiFi.h>

#endif

void setup(){

Serial.begin(115200);

Serial.println();

Serial.print("ESP Board MAC Address: ");

Serial.println(WiFi.macAddress());

}

void loop(){

}

After uploading the code, reset your WeMOS D1 to see your MAC address in Arduino IDE serial monitor.

Copy it and save the MAC address as we need it further. In transmitter code, we must specify the MAC address of the WeMOS D1 mini.

//Replace it with your ESP's MAC address in the transmitter code

uint8_t broadcastAddress1[] = {0xAA,0xDD,0xC1,0xB2,0xE3,0xD4};

Connection

DHT11 signal pin is connected with D2 pin of ESP32, VCC to 3.3v of ESP32 and ground to GND pin respectively. The connection is simple and easy.

Using the functions makes it easy for you to use this library and allows you to create a responsive dashboard that is accessible via the module IP address. This library will allow the user to set up a web server using predefined functions, as well as a dashboard with graphical plugins to monitor values. You will be able to change the display of these values ??depending on the type of input data.

Code

code

C/C++

#include "DHT.h"

#define DHTPIN 4     // Digital pin connected to the DHT sensor
// Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 --
// Pin 15 can work but DHT must be disconnected during program upload.

// 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 procs.
DHT dht(DHTPIN, DHTTYPE);

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

  dht.begin();
}

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

  // 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(F("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(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.print(F("°C "));
  Serial.print(f);
  Serial.print(F("°F  Heat index: "));
  Serial.print(hic);
  Serial.print(F("°C "));
  Serial.print(hif);
  Serial.println(F("°F"));
}

Schematic and Layout

circuit

lolin32-and-dht11_bb.webp

Jul 25,2022

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