This hobby project consists of a three-light and buzzer, 12V Skoda signal tower mounted in a standalone box. The signal tower is controlled by a Nodemcu microcontroller, with software written in the Arduino IDE.

The lights on the signal tower can be controlled either by:

• a fitted push button; pushing it briefly switches to the next light, pushing it longer switches to the previous light like so: green, green+yellow, yellow, yellow+red, red. And then back to green.
• a JSON message published on a specific Mosquitto (MQTT) topic.

The buzzer can only be controlled by the same JSON message.

The format of the JSON message is:

{ "colors": {"green":"[on|x]", "yellow":"[on|x]", "red":"[on|x]"}, "buzzer":"[on|x]" }

The meaning of "[on|x]" is really "the string 'on', or any other string". Meaning that code only checks for the string "on", anything else is considered "off".

Network credentials should be made available in a file 'credentials.h', looking like this:

#define SSID "yourssid"
#define PASSWORD "somepassword"
#define CONNECTION_ID "MQTTclientID"
#define CLIENT_NAME "MQTTclientname"
#define CLIENT_PASSWORD "MQTT password"

The code is written for the NodeMCU (ESP8266). It should be easy to run this on many other devices, provided the libraries that it uses are supported:

• ArduinoJSON
• ESP8266WiFi
• FSM
• PubSubClient

This code is released under the GPL v3.

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