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DHT Temperature sensor example

Pre Installation

What will you need:

  • Arduino board, or any other development board as Node MCU or any other you may like
  • ESP8266-12 Chip, ESP8266-12x model is needed, but once you got the code you could use other chips (Node MCU already have an on board ESP8266)
  • Solderless Plug-in Breadboard, 830 Pin recommended
  • Male-Female and Male-Male Jumper Wires, You will need both types
  • 10K, 1K, 220 ohm Resistors, Usually comes in large quantities as they are very cheap, around 2 USD for 100 units on eBay
  • 4-pin Tactile Switch, Extremely cheap, eBay prices around 2 USD for 50 units
  • DHT22 Temperature Sensor, eBay prices of around 3 USD
  • LED, Regular LEDs from eBay cost around 2 USD for 100 Units

Setup Hardware

Connecting electronics - Temperature sensor

  • Note that using Arduino 3.3v as power source for the ESP8266 may cause random behavior. Personally for development I used Arduino as my power source and all worked ok, but again it usually don't provide enough power.

Connect all components according below image

  • Arduino 3.3v pin to LOWER part of the board

  • Arduino 5v pin to UPPER part of the board

  • Arduino GND to any of the GND Line of the board (Connect both Black GND Lines of the board)

  • Arduino GND to Arduino reset pin

  • ESP VCC pin to 3.3v (LOWER) part of the board

  • ESP GND pin to any GND line on the board

  • ESP RX pin to Arduino RX pin

  • ESP TX pin to Arduino TX pin

  • ESP GPIO00 pin Connected to any GND to "FLASH" the code (button is pushed, explained later)

  • ESP GPIO15 pin Connected to any GND with a 10k resistor

  • ESP RESET pin Connected to 3.3v (LOWER) with a 10k resistor, and to GND behind a push button, ESP8266 will restart on button press

  • ESP CH_PD pin Connected to 3.3v (LOWER) with a 10k resistor

  • ESP GPIO12 pin Connected to LED with 220 resistor (LED long leg - Anode, to resistor, LED short pin - Cathode, to GND)

  • ESP GPIO13 pin Connected to GND (Pulled low) behind push button, and to 3.3v with 1K resistor

  • DHT22 pin no.1 to 5v (UPPER)

  • DHT22 pin no.2 to ESP GPIO04 pin and to 5v (UPPER) with a 10k resistor

  • DHT22 pin no.4 to any GND

Arduino IDE

Download Arduino IDE,
Once installed git clone https://github.com/ArieLevs/NalkinsCloud-ESP8266.git and open it with Arduino IDE

Setting up configuration files

Go to ConfigFile.h, Change line const char* fingerprint = ""; // SHA1 - 60 Bytes With your MQTT Broker certificate SHA1 fingerprint,
Example of the fingerprint structure inside that file,
In order to get SHA1 fingerprint from .crt file use openssl x509 -noout -fingerprint -sha1 -inform pem -in [FILE_NAME].crt

If you need any additional libraries that are not included with default installation of the Arduino IDE go to Sketch > Include Library > Manage Libraries

Press verify on the upper left corner to compile the code, make sure code successfully compile.

Uploading code to ESP8266

Add the ESP8266 board, go to Tools > Boards > Boards Manager
Search for esp8266 and install

Select the just installed board, go to Tools > Boards > Select 'Generic ESP8266 Module'

Once all successfully compiled hold "FLASH" (GPIO00) button so it will be grounded, while pressing "FLASH" button, press "RESET" button to restart the chip, then release all buttons.
By doing this action you will be able to write code on the ESP chip.

Press upload and wait until the process is done, by opening the monitor Tools > Serial Monitor you could see logs being returned to the screen.

Please note - in order for the device to be able to communicate with MQTT broker, you must complete Mosquitto server installation at NalkinsCloud