433Mhz <-> MQTT gateway with some extras

The mqtt-433mhz-gateway-homie project is a simple bidirectional gateway to transmit and receive 433Mhz RF signals connected to MQTT. The gateway is built with a cost-effective ESP8266 WiFi chip (I used a Wemos D1 mini, NodeMCU will do as well), simple 433Mhz RF modules and an additional BMP085 sensor.

It enables to:

• receive MQTT data from a topic and send the 433Mhz signal
• receive 433Mhz signal from a traditional remote, optional map it to a channel and publish the data to a MQTT topic
• additional a simple temperature sensor can record the room temperature of the room where the gateway is installed

The software is based on Homie to enable an easy integration with home automation systems like OpenHab.

Hardware

• ESP8266 (Wemos D1 mini, Nodemcu)
• RF Receiver 433Mhz
• RF Transmitter 433MHz
• BMP085 or BMP180 sensor breakout

I got the RF modules form https://www.sparkfun.com, others will do as well. Additional I got some Wemos Protoboards, an USB power supply with a very short cable and an enclosure to keep all together.

Building the circuit

Wemos D1 mini	BMP085	RF Receiver	RF Transmitter
5V	VIN	VIN	VIN
GND	GND	GND	GND
D0			DATA
D1	SCL
D2	SDA
D5		DATA

Software

The following software libraries are used. When using PlatformIO all dependencies are resolved automatically.

• Homie V2 (dev) including dependencies
• RCSwitch
• Adafruit BMP085 Unified
• Adafruit Unified Sensor
• Optionally PlatformIO environment for building the code

MQTT

For a detailed documentation of the MQTT topics and commands used see Homie documentation.

Sample gateway messages:

# sensor temperature reading
homie/mqtt-gateway-livingroom/temperature/degrees 23.70

Temperature value send form device.

# send RF command via MQTT & response
homie/mqtt-gateway-livingroom/MQTTto433/on/set 1394001
homie/mqtt-gateway-livingroom/MQTTto433/on 1394001

First line: MQTT command send from MQTT client or smart home solution. Translates into the code send by the RF transmitter. Second line: Response from device after RF signal was send.

Config

The following config parameters are available via MQTT message (see Homie documentation how to use):

Parameter	Type	Usage
temperatureInterval	long	temperature reading interval in seconds
temperatureOffset	double	temperature offset (-/+) to correct the sensor reading, for example if used in enclosure box
channels	const char*	mapping of 433MHz signals to mqtt channels, useful if used with OpenHab

All configs can be set during the init procedure of the module or via MQTT messages (see Homie specification).

Sample config:

{
    "settings": {
        "channels": "o-1:[139400];o-2:[139707];o-3:[1398097,1398100];o-4:[139803];i-1:[44618];i-2:[44620];i-3:[44623];i-4:[44638];i-5:[44700];“,
        "temperatureOffset“: -2.4,
        "temperatureInterval": 300
    }
}

Credits

This project is was inspired by 1 Technophile's 433toMQTTto433 solution.