Make Bluetooth device


This is a tutorial how to make a simple Arduino based device which could read temperatures from Thermocouple and translate them to the app over BLE (Bluetooth Low Energy) technology.

I made this tutorial presuming you have some experience with Arduino and know how to work with micro-controllers. Once I have more time I will update this tutorial adding more details and images to make it easy understand for beginners as well. But until then I hope somebody will share own experience with others to help them.

Disclaimer. This tutorial is for your guidance only and I am not taking any responsibility. Proceed further only if you know what are you doing. If you don’t know how to do that please ask other for help or wait until pre-programed ESP32 boards or ready to use devices will be available.

Alternatively you can send me your requests and I will try to make device for you. 

Thing you need to buy

  • ESP32 board (with BLE) were the Arduino code lives. On the Amazon (UK) it costs £8.99
  • MAX6675 board – communicates and takes readings from Thermocouple. On the Amazon (UK) it costs £3.90

  • Thermocouple K or any other compatible to work with MAX6675. On the Amazon (UK) it costs £4.99

You can get MAX6675 and Thermocouple cheaper if you buy them together as a bundle.

Connecting hardware and flashing code

Connecting ESP32 board

  • Red – V5 (+5V)
  • White – GND (Ground or -)
  • Yellow – G12
  • Orange – G14
  • Green – G27

Connecting MAX 6675

  • Red – VCC (+5V)
  • White – GND (Ground or -)
  • Yellow – CSK
  • Orange – CS
  • Green – SO

Flashing code to ESP32 board

  • Download the code for Arduino.
  • Launch Arduino IDE software.
  • Install all required libraries (see description in code).
  • Connect ESP32 board (Micro USB connection) with your computer.
  • Choose the ESP32 board on the Arduino IDE

  • Flash the code to the ESP32 board and reset ESP.
  • If you did all steps correctly you will be able to debug or connect device to the app. Check video how to connect to BT device

Happy roasting