Warehouse Locator - An LED based stock search helper

Identifying a specific stock items inside a dense environment, such as a warehouse, is difficult so we developed a LED strip based system that lights up around the stock item requested.

This system is connected via WiFi to a MQTT broker and is able to receive commands to light up any given set of LEDs.

Set up the server

The server is simply a MQTT broker. To setup the server you need to install Docker and Docker Compose.

1. Because this will be a publicly accessible MQT broker,before you run the server, you need to define its access credentials. For that create a file on server/mosquitto/mosquitto.passwd with your user and password separated by a colon, here is an example:

   lcdporto:very-strong-password

2. Then you are ready to start the server:

docker-compose up -d

3. Before you can use it you need to encrypt the password file:

   docker exec -it mosquitto mosquitto_passwd -U /mosquitto/config/mosquitto.passwd

4. Then restart your server with:

   docker-compose restart mosquitto

   Now your server is up and running!

Prepare your device

You can change this pin assignment as well as add more LED strips on the firmware. Your limitation is the RAM usage and the pin count of your board.

1. First you need to setup your computer to build the firmware with one of the two methods:

   • At the time of this writing the recommended method is to use VS Code and the official PlatformIO extension which is a procedure that works on Windows, macOS and Linux foloowing the the official documentation..\
   • You can also use a CLI approach that is available on all major platforms as well which have Python installed (follow this guide) and then on the firmware folder run the following lines on the terminal of your operative system:

     pip install --user platformio
     pio run --target upload

     Note: you may need to reboot your system between the two commands for the pio executable to be available.

2. Next, you need to configure your device's WiFi network and MQTT broker details. To do that, power up your device and search for a WiFi network named after this project "warehouse-locator-\<ID>" (note down the ID, or check later with this). Connect to it and you should be promted to login to the network on a captive portal. There is where you find a form to fill in your WiFi credentials and MQTT server details. If your device fails to connect to the network the configuration WiFi network will show up again after a few seconds.\ Alternatively, you can upload a file containing the MQTT server details (firmware/data/config.json) to the ESP32 filesystem following the this guide. Keep in mind that you still need to follow the captive portal procedure to enter your WiFi credentials.

Now your device is connected to the internet and able to receive messages from your broker that change the state of the LED strips you have hooked up.

Discover connected devices

To discover connected devices and check their ID, the topic warehouse-locator/+ can be subscribed and devices will periodically publish on that topic to announce themselves and you can check their ID on the topic name they use. Notice that the subscription topic suggested has the "+" wildcard, this means you'll subscribe to all devices announce topic.

An example on how you can listen to these messages is here.

Send commands

The device can be controlled by sending a MQTT message to the broker identifying the device, led-strip and led index and two modes are supported:

Single LED control

Topic: warehouse-locator/<deviceId>/<strip-id>/<led-id>\ Payload:

{
  "color": {
    "r": 0,
    "g": 255,
    "b": 0
  },
  "timeout": 5
}

Multiple LED control

Topic: warehouse-locator/<deviceId>/multiple\ Payload:

{
  "strip": 3,
  "from": 1,
  "to": 4,
  "color": {
    "r": 255,
    "g": 255,
    "b": 255
  },
  "timeout": 5
}

Note: For maintenance purposes the LEDs can be blinked sequentially if the payload is not a JSON object and just set to all

Examples for both modes can be found at the examples folder.