MQTT To MDB Bridge

Atmega2560 Code(Arduino Mega)

Pre Requirements

The following should be installed in your PC

• AVR-GCC
• AVRDUDE
• avr-libc

Installing Pre-Reqs on Linux(Ubuntu or Debian Based Distro)

On Ubuntu or any Debian based Linux distro execute the following commands

• sudo apt-get install -y gcc-avr
• sudo apt-get install -y avrdude
• sudo apt-get install avr-libc

Setup

1. Open terminal in the atmega2560FW folder and execute make clean
2. Open makefile, replace P=COM1 to the COM port of your arduino mega and save the file 1. Compile it with make all
3. Upload it to your Arduino with make program

ESP32 Code

Pre Requirements

You should have Arduino IDE Installed

1. Add ESP32 Board to your Arduino IDE 1. In your Arduino IDE, go to File> Preferences Installing ESP32 Add-on in Arduino IDE Windows, Mac OS X, Linux open preferences 2. Enter https://dl.espressif.com/dl/package_esp32_index.json into the “Additional Board Manager URLs” field then, click the “OK” button: Note: if you already have the ESP8266 boards URL, you can separate the URLs with a comma as follows: https://dl.espressif.com/dl/package_esp32_index.json, http://arduino.esp8266.com/stable/package_esp8266com_index.json 3. Open the Boards Manager. Go to Tools > Board > Boards Manager… 4. Search for ESP32 and press install button for the “ESP32 by Espressif Systems“: 5. That’s it. It should be installed after a few seconds.

2. Now copy the contents of the libs folder to the libraries directory of your Arduino 1. If you are using windows, the libraries directory will be Documents/Arduino/libraries

3. Select ESP32 Dev Kit from Tools->Board->ESP32 Dev Kit

4. Select the correct port from Tools->Port

5. Then in ESP32FW.ino file, on line number 13 and 14, put your WiFi creds

6. Upload the Code to your ESP32

+ broker used is borker.hivemq.com
+ vending can be done by publishing an ammount to mdb/invoke topic

Note: for more details, you can see MQTTHandler.h file

Circuit Diagram

Short Wire A and Wire B to start the MDB communication or put an on/off button

The parts used in this circuit are:

• Optocoupler OHPC 817C F919G
• • Datasheet
• Schimitt Trigger Hex Inverter PHILIPS 74HC14N B9784PS Hnn9840 E
• • Datasheet
• Diode 1N4007 MIC AXIAL SILASTIC GUARD JUNCTION STANDARD RECTIFIER
• • Datasheet
• Resistor 330 ohms
• Arduino Mega 2560
• ESP32 Dev Kit