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Basics: Project 066d

Project name: ESP8266 ESP-12E WI FI module (LoLin NODEMCU V3), DHT 11 21 22 module - ThingSpeak

Tags: ESP, ESP8266, WI FI module, ESP-12E, Ai Thinker, AI-Cloud, SOC, GPIO, General Purpose Input Output, System On a Chip, IOT, internet of things, how to upload sketch, blink sketch for ESP8266 ESP-12E module, LoLin NODEMCU V3, NODEMCU, V3, Development Board with USB-to-Serial Onboard, NodeMCU DevKit, IOT STARTUP, DHT 11 22 21 module, temperature, humidity, ThingSpeak

Attachments: sketch, library3, library4, library5

In this project, you need these parts :

1. ESP8266 ESP-12E WI FI module with micro USB cable 1pc

2.Arduino IDE ( you can download it from here  )

3.Jumper cables F-M, FM-M

4. Breadboard 1 pc

5. DHT11 21 22 Humidity and temperature module 1 pc

6. Resistor 1 pc (10 KOhm)

General

We will learn how to build a sensor node with an ESP8266 ESP-12E wifi module that publishes the temperature and humidity from DHT 11/21/22 module once a day to Thing Speak.

Understanding the DHT module

You can read more about it here.

Understanding the ESP8266 ESP-12E WI FI module (LoLin NODEMCU V3)

The ESP8266 WiFi Module is a self contained SOC (System On a Chip) with integrated TCP/IP protocol stack that can give any microcontroller access to your WiFi network.

The ESP8266 WiFi Module is capable of either hosting an application or offloading all Wi-Fi networking functions from another application processor.

Each ESP8266 WiFi Module comes pre-programmed with an AT command set firmware, meaning, you can simply hook this up to your Arduino board and get about as much WiFi-ability as a WiFi Shield offers.

The ESP8266 WiFi Module is an extremely cost effective board. This module has a powerful enough on-board processing and storage capability that allows it to be integrated with the sensors and other application specific devices through its GPIOs (General Purpose Input Output) with minimal development up-front and minimal loading during runtime. Its high degree of on-chip integration allows for minimal external circuitry, including the front-end module, is designed to occupy minimal PCB area. The ESP8266 supports APSD for VoIP applications and Bluetooth co-existance interfaces, it contains a self-calibrated RF allowing it to work under all operating conditions, and requires no external RF parts.

In short, the ESP8266 module is a TTL "Serial to Wireless Internet" device, a small microprocessor with built in wi-fi. It is faster than most Arduino boards and has more memory than most Arduino boards and has less pins than an Arduino board.

The ESP8266 comes in a wide variety of versions (as shown in the figure below).

Application:

• create a web server
• send HTTP requests
• control outputs
• read inputs and interrupts
• send emails
• post tweets

HOW DOES IT WORK

The ESP8266 WI FI module can be controlled from your local wifi network or from the internet (after port forwarding set on your router). The ESP8266 communicates with the Arduino through a serial interface.  It uses the Arduino’s Rx and Tx pins (digital pins 0 and 1) connected to the ESP8266 ESP-12E module for receiving commands and communicates back. The module features a full TCP/UDP stack support and can be configured as a web server. 

ESP8266 ESP-12E module

We will use ESP8266 ESP-12E module in this project. 

Out of the many ESP-NN modules that have been released, ourselves alongside the rest of the ESP8266 community became fond of the FCC-certified ESP-12E, also known as the ESP-12F given that the first versions of the ESP-12E weren't FCC-certified!

The ESP-12E module breaks out all the available ESP8266 pins, and it includes a visible LED for indicating the status of the SoC's Tx pin, which is very useful during programming.  In addition, under the tin can, the ESP-12E a 4MB SPI flash storage IC – typically the Winbond W25Q32FV, and all the necessary components needed for the onboard ESP8266 to operate properly (e.g., crystal, capacitors, resistors). It also includes an onboard antenna with a reasonable range (–70~–80 dBm at 50 feet).

Features:

• ESP8266 ESP-12E module
• Built-in USB to Serial UART Adapter (CP2102 or CH340)
• Reset button
• Input button (also used for bootloading)
• Surface-mount, user-controllable red LED
• 3.3V 500mA voltage regulator (LM1117 or AMS1117)
• Two diode-protected power inputs (one for a USB cable, another for a battery)
• No need to press reset/flash for progamming
• Supports Wi-Fi protocol 802.11 b / g / n;
• Supported modes Wi-Fi - access point, client;
• The input voltage is 3.7V - 20V;
• Operating voltage 3V-3.6V;
• The maximum current is 220mA;
• Built-in TCP / IP stack;
• Operating temperature range from -40С to 125С;
• 80 MHz, 32-bit processor;
• Time to wake up and send packets 22ms;
• Built-in TR switch and PLL;
• The presence of power amplifiers, regulators, power management systems.

There are several generations of NodeMcu boards - V1 (version 0.9), V2 (version 1.0) and V3 (version 1.0). The designations V1, V2, V3 are used for sale in online stores. Often there is confusion in the boards - for example, V3 is externally identical to V2. Also, all boards work on the principle of open-source, so they can be produced by any company. Amica, DOIT and LoLin / Wemos are the main makers of NodeMcu boards.

V1 and V2 are easy to compare - they have different sizes. Also, the second generation is equipped with an improved modification of the ESP-12 chip and 4 MB of flash memory. The first version, obsolete, is made in the form of a bright yellow platform. It is inconvenient to use it, since it covers 10 outputs of the breadboard. The second generation made to correct this disadvantage - it has become narrower, the outputs are well suited to the board's contacts. The V3 boards same as V2 but have a more reliable USB-output. The LoLin board is manufactured by LoLin, from differences from the previous board, it can be noted that one of the two reserved outputs is used for additional ground, and the second one is for feeding USB power. Also, the board is larger than the previous ones.

The ESP-12E is a great breakout for the ESP8266, however, in order to maintain a small footprint it's been designed without any holes for pin headers. Rather than a breadboard-able module, the ESP-12E is meant to be mounted on a PCB.  Moreover, to further increase the usability of the ESP-12E during rapid prototyping, some power regulation and USB connectivity are necessary.  This is what ourselves and other US-based DIY Electronics vendors have contributed to the ESP8266 ecosystem.  In our case we've developed a board that includes, among other passive components and discrete ICs, a CP2102 or CH340 USB to Serial UART adapter, a NCP1117 (AMS1117) 3.3 VDC Voltage Regulator, a micro-USB connector, and through-hole (male) pin headers.

This board breaks out all the (available) ESP8266 pins to through-hole headers for easy breadboarding.  The board also includes additional GND, Vin, 3.3VDC signals for easy access during development.  This development board for the ESP8266 SoC inside the ESP-12E module is out-of-the-box ready for you to connect it to your computer, install USB drivers, and start writing programs that connect to your Wi-Fi network!

You can find more about NodeMCU DEVKIT V1.0 here.

NodeMCU

NodeMCU is, at the moment, the most popular alternative firmware that runs on the ESP8266.  Based on the eLua project, it runs a Lua interpreter onboard the ESP8266, which is able to execute commands written in the Lua scripting language.  The commands are sent to the ESP8266 via the Serial UART interface.

NodeMCU is a great starting point for Makers as it provides an interactive environment that allows running commands not only for controlling the ESP8266's wireless interface, but also its GPIO and hardware functionality such as PWM.  In addition, we have access to the full scope of the Lua programming language for writing our applications.  In the case of the default firmware (AT+Commands Interpreter), the application code would have to be developed using a programming language suited to the host microcontroller or SoC that would be sending the commands over Serial (e.g., C/C++ for the Atmel/ARM microcontrollers on Arduino boards).

Not only does the NodeMCU firmware allows us to execute commands interactively, but we can save our applications as a script in the ESP-12E's flash memory, and instruct it to run the application code every time it restarts!

ESP8266 ESP-12E module has three operational modes: 

1. Access Point (AP) — In AP, the Wi-Fi module acts as a Wi-Fi network, or access point (hence the name). It allows other devices to connect to it. And establishes a two-way communication between the ESP8266 and the device that is connected to it via Wi-Fi. 

2. Station (STA) — In STA mode, the ESP-12E can connect to an AP (access point) such as the Wi-Fi network from your house. This allows any device connected to that network to communicate with the module. 

3. Both — In this mode ESP-012E act as both an AP as well as in STA mode. Refer to the following site for more ESP8266 AT commands. 

Disadvantages of the NodeMcu module

The main disadvantage is the ability to execute only LUA scripts located in the RAM. This type of memory is small, the volume is only 20 KB, so writing large scripts causes a number of difficulties. First of all, the whole algorithm will have to be divided into linear blocks. These blocks must be written to separate files on the system. All these modules are executed using the dofile operator.

At writing it is necessary to observe a rule - at data interchange between modules it is necessary to use global variables, and at calculation inside of modules - local. It is also important to call the collectgarbage (garbage collector) function at the end of each written script.

ESPlorer

Signals and connections of the DHT module

There are two different versions of the DHT11 you might come across. One type has four pins, and the other type has three pins and is mounted to a small PCB. The PCB mounted version is nice because it includes a surface mounted 10K Ohm pull up resistor for the signal line. Here are the pin outs for both versions:

Signals and connections of the ESP8266 ESP-12E WI FI module (LoLin NODEMCU V3)

TX - transmit pin. GPIO pin

RX  - receive pin.  GPIO pin

3V3 (or 3V or 3.3V) - power supply pin (3-3.6V). 

GND ( or G) - ground pin.

RST - reset pin. Keep it on high (3.3V) for normal operation. Put it on 0V to reset the chip.

EN - Chip enable. Keep it on high (3.3V) for normal operation.

Vin - External power supply 5VDC.

D0-D8 - GPIO (General Purpose Input Output) pins 

D5-D8 - SPI interface

D1-D2– I²C/TWI Interface

SC (or CMD) - (Chip Select) - the pin that the master can use to enable and disable specific devices. GPIO pin

SO (or SDO) - Master In Slave Out (MISO) - SPI communication. The Slave line for sending data to the master. GPIO pin

SK (or CLK) - SCK (Serial Clock) - SPI communication.The clock pulses which synchronize data transmission generated by the master. GPIO pin

S1 (or SD1) - Master Out/Slave In (MOSI). SPI communication. The Master line for sending data to the peripherals. GPIO pin

S2 (or SD2) - GPIO pin

S3 (or SD3) - GPIO pin

VU (or VUSB) - external power 5VDC.

A0 - ADC output.

RSV - reserved

Wiring

The DHT module should be connected to GPIO 5 (D1 pin marked on the module).

Step by Step instruction

1. Adding ESP8266 platform to Arduino IDE

The Arduino environment has to be set up to make it compatible with the ESP8266 ESP-12E module. It is required to have Arduino IDE version 1.6.4 or higher in order to install the ESP8266’s platform packages.

1. Open Arduino IDE. 
2. Open the Preferences window from the Arduino IDE. Go to File -> Preferences.
3. 
4. Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Board Manager URLs field and click the “OK” button. If you already have a URL in there, and want to keep it, you can separate multiple URLs by placing a comma between them. (Arduino 1.6.5 added an expanded text box, separate links in here by line.)
5. 
   
6. Open Boards manager. Go to Tools -> Board -> Boards Manager…
7. 
   
8. There should be a couple new entries in addition to the standard Arduino boards. Look for esp8266. or scroll down to the ESP8266 entry (usually at the bottom). Select the ESP8266 entry. When you click it an install option will appear. Select the latest version and click install. 
9. 
10. The board definitions and tools for the ESP8266 include a whole new set of gcc, g++, and other reasonably large, compiled binaries, so it may take a few minutes to download and install (the archived file is ~110MB). Once the installation has completed, an Arduino-blue “INSTALLED” will appear next to the entry.
11. 
12. 

2. Registering with Thing Speak and creating a channel

Thing Speak (ThingSpeak.com) allows you to send and publish your sensor readings to their website and display them in a plot with time stamps. You can access your readings from anywhere in the world. Of course this project can be easily modified to publish the values to your home automation hub or another application instead of Thing Speak. 

We will show you how you can put your ESP8266 in deep sleep mode, publishing a value every 24 hours.

1. Go to ThingSpeak.com
2. 
3. If you don’t have an account on Thing Speak you need to make it. Enter your email address, User ID, password, first name, last name and select the place you leave. Tick on box for I accept Online Services Agreement:
4. 
5. Press Continue button. Email will be automatically sent to your email address.
6. Go to your inbox for your email address.
7. Click on the link in email which you received from mathworks.com.
8. 
9. 
10. 
11. After your account is ready, sign in and open the Channels tab.
12. 
13. Press the New Channel button to make a new channel.
14. 
15. Type a name for your channel, add a description, and enable a second field. Field 1 will receive the Humidity readings and Field 2 the Temperature readings. 
16. 
17. You can also add additional data. 
18. 
19. Once you’ve completed all these fields, press Save channel button to save your channel.
20. These charts can be customized. Go to your Private View tab and press the edit icon.
21. 
22. You can give each chart a title, for example the first chart will be called Humidity % and my second chart will be called Temperature *C.
23. 
24. 
25. You can also change background color, x and y axis, and other settings. When you finished, press Save button.
26. You need the Write API Key to publish your values. Open the API Keys tab and copy the Write API Key because you will need it.
27. 

3. Uploading sketch to ESP8266 ESP-12E module 

 If you’re using an ESP-12E NodeMCU Kit, uploading the sketch is very simple, since it has built-in programmer. 

Before use ESP8266 ESP-12E WI FI module (LoLin NODEMCU V3), you need to download the manufacture's driver (CH340)  for this chip and install it in your PC. Here is the link. See the description of driver installation package below: CH340 / CH341 USB to serial WINDOWS driver installation package that supports 32/64 bit Windows 10 / 8.1 / 8/7 / VISTA / XP, SERVER 2016/2012/2008/2003, 2000 / ME / 98, through Microsoft digital signature authentication, support USB to 3-wire and 9-wire serial port, with the product release To the end user. Applicable scope: CH340G, CH340C, CH340B, CH340E, CH340T, CH340R, CH341A, CH341T, CH341H chips.

If you have CP2102 chip then  you need to download the manufacture's driver for this chip and install it in your PC. Driver for Mac, Windows, Linux or more.. 

1. Do wiring.
2. Open Arduino IDE.
3. Plug your ESP8266 ESP-12E module into your PC USB port.
4. Choose your NodeMCU board. Go to Tools -> Board -> NodeMCU 1.0 (ESP-12E Module)
5. Select the correct com port.
6. Replace the SSID, password, Thing Speak WRITE API KEY with your own data.
7. Verify and upload the sketch to your ESP8266 ESP-12E module. AT commands will not work after that. You need to Flash the firmware to enable them again.
8. Open Serial monitor at baud rate of 115200 bps.
9. You can test if your code operational and simulate each hour passing. Simply remove the wire that connects the RESET pin to D0 (GPIO 16), and then you just have to press the RESET button on your ESP8266 ESP-12E WI FI module (LoLin NODEMCU V3) to simulate each hour passing.
10. Press RESET button 24 times to publish a reading. The counter variable increases every time you press the reset button. As you can see the Humidity and Temperature readings have been successfully published and plotted in the chart in real time.
11. 
12. 
13. Once you reset the ESP8266 24 times, it will publish the readings to Thing Speak. After testing complete, you should reconnect the wire from RESET to D0. The ESP will wake up every hour, but it will only publish a value every 24 hours.

Codes

Replace the SSID, password, Thing Speak WRITE API KEY with your own data.

The setup() function begins from initialising the serial communication at 115200 bps. Then the ESP daily task function called to determine whether 24 hours have passed or not since the last reading. If not, the ESP goes back to deep sleep mode. If 24 hours have passed since the last reading the code will initialize the DHT sensor, connect to the Wi-Fi router and make an HTTP GET request to ThingSpeak in order to publish the readings. Once the readings published, the ESP goes back to deep sleep mode. There is nothing in the loop() function as your ESP is all the time in deep sleep mode and wakes up itself.

Please note that if you are using a different sensor than the DHT11, you can comment and uncomment the DEFINE line in order to use correct sensor. By default this code publishes the temperature in Celsius, but if you comment the variable dtostrf(hic, 6, 2, temperatureTemp); and uncomment the variable dtostrf(hif, 6, 2, temperatureTemp); it will publish the temperature in Fahrenheit.

Summary

We have learnt how to build a sensor node with an ESP8266 ESP-12E wifi module that publishes the temperature and humidity from DHT 11/21/22 module once a day to Thing Speak.

Library

• ESP8266WiFi library included in Arduino IDE. 
• ESPDailyTask library. Download, unzip  and add to libraries in our PC, for example C:\Users\toshiba\Documents\Arduino\libraries. This link you can find in Preferences of Adruino IDE program which installed in your PC. You can read more about it here. You can find it on the begining of this project.
• Adafruit_Sensor library included.Download, unzip  and add to libraries in our PC, for example C:\Users\toshiba\Documents\Arduino\libraries. This link you can find in Preferences of Adruino IDE program which installed in your PC. 
• DHT-sensor library included. You will need to unzip and add the DHT-sensor-library-master library to libraries in your PC, for example C:\Users\toshiba\Documents\Arduino\libraries OR You can install it in Arduino IDE too: select Sketch-> Include library->Manage your libraries->type DHT in Filter your search line and you will see DHT sensor library by Adafruit->More info->select version->install. If it will be problem with compilation - remove 2 files from the library - DHT_U.cpp and DHT_U.h.

Sketch

• You can find it on the begining of this project