433Mhz <-> MQTT gateway with some extras

Smart Home 433Mhz RF <-> 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 you 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.
additionally, 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 easy integration with home automation systems like OpenHab.

The final assembly looks like this:

final assembly

Hardware

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

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

The circuit inside the enclosure box:

final assembly in box

Building the circuit

The wireing of the gateway project is very easy. The sensor, the transmitter and the receiver must be connected to VIN & GND and the GPIO pins of the ESP8266 board as shown in the table below.

Fritzing Diagram

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

Source code on GitHub

MQTT

For 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 from 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 a device after the RF signal was transmitted.

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.