Radio sensors NET

Introduction

This project will allow to aggregate, process and visualise data collected from a network of wireless sensors. Main purpose of it is to use it as a base of my own smart home system.

Probably you are lost if you are reading this README. The project is still in a hacking phase. I check different possible solutions and ways to proceed. Don't expect anything.

Check Issues for TODO.

This README for now is just my notebook. It will get a shape later.

Used resources

This project heavily utilizes RF24 libs.

MQTT usage is implemented with PubSubClient library.

What works so far

1. Prototype of a arduino-based hardware.
2. Publishing of temperature and humidity data.
3. Arduino can be configured over serial connection.
4. BeagleBone Black with RF24Gateway properly transfers MQTT data from sensors to Mosquitto MQTT broker.

System architecture

The system consists of:

• Radio part

  1. Sensor layer
  2. RF24 Gateway

• Cloud part

  1. MQTT Broker
  2. MQTT to DB bridge
  3. Database
  4. Presentation layer (WebUI)

Radio part

Sensor layer

Hardware limitations

Arduino flash size problems

Initially, sensor used MQTT subscriptions as alternative way to set configuration data. Unfortunatelly, RF24 Ethernet library is quite heavy for arduino in terms of code size.

Arduino TCP stack performance

Take a look at the RF24Ethernet issue #17 and PubSubClient issue #216. Probably arduino is not able to handle to many task at the same time - especially publishing and receiving notification about subscribed topics.

TODO: It should be checked whether similar problems are occuring when using ethernet shield.

DHT22

Used library: https://github.com/RobTillaart/Arduino/tree/master/libraries/DHTlib

MQTT topic architecture

r/l/<location: char[8]>/s/<id: uint8_t>/t - temperature
r/l/<location: char[8]>/s/<id: uint8_t>/h - humidity
r/l/<location: char[8]>/s/<id: uint8_t>/v - voltage

Serial console

There are two types of commands which can be executed over serial console:

SET commands

S,<name>,<value>

Modifies given variable in the system. Where <name> is:

• id: uint8_t - sensor id
• loc: char8 - sensor location
• sip: ipaddress - sensor ip address
• gip: ipaddress - rf24 gateway ip address
• bip: ipaddress - MQTT broker ip address

GET commands

G,<name>

Prints given variable. Where <name> is:

• id: uint8_t - sensor id
• loc: char8 - sensor location
• sip: ipaddress - sensor ip address
• gip: ipaddress - rf24 gateway ip address
• bip: ipaddress - MQTT broker ip address

RF24 Gateway

Cloud part

MQTT Broker

MQTT to DB bridge

Python based bridge build with Paho-MQTT.

Database

Presentation layer (WebUI)