Hobby IoT

An Open source IoT adventure

HobbyIoT Helium sensor development platform

The project is intended to simplify the development of open source LoRaWAN Helium connected nodes - from sensor devices to tracking modules with battery power. You can see on the picture there is a small development area where one can solder sensors or other expansion modules to connect. General purpose pins from the microcontroller together with powering are routed to that area. I also included LiPo battery charger and, even RaspberryPi compatible connector with I2C interfaces and power line routed!

Introduction

Time ago I found the potential of the People’s network (The Helium network, https://www.helium.com/) to connect and transfer data securely and reliably around the world. I learned there is a constant growth of commercial Helium devices one can buy and use. Unfortunately the open source projects tailored according to Helium capabilities and advantages are not quite popular so far…

The project is intended to simplify the development of open source LoRaWAN Helium connected nodes - from sensor devices to tracking modules with battery power. You can see on the picture there is a small development area where one can solder sensors or other expansion modules to connect. General purpose pins from the microcontroller together with powering are routed to that area. I also included LiPo battery charger and, even RaspberryPi compatible connector with I2C interfaces and power line routed!

Story

The Helium adventure started with a hotspot antenna installed near the home window...

Coming from the product development world my first thought was how to send data over that network! Digging out the Internet, no suitable solution was found. Just experiments and some LoRaWAN libraries for Arduino. That was the key to start developing my own, open source Arduino platform with LoRaWAN module and other hardware and with the help of the software libraries available!

First experiment was on a breadboard. Small Arduino Pro Mini and a LoRa module from a local hobby store! After some tunings the first packets over the Helium network were sent!

I added a small LiPo battery and a standard plastic box and went around to check Helium network connectivity across the town and even in the nearby mountain Vitosha!

Coverage was 100 %! No lost transmissions!

That success boosted the development moving higher up to the ESP32 based MCU module and adding a small positioning module. First experiments were on a breadboard using a GNSS development kit from uBlox.

The big step came with the development of our own board with ESP32, compact LoRaWAN SX1276 module and GNSS module. In addition several general purpose I/Os and I2C interfaces were routed together with a small development area for sensor soldering. And, of course, a battery charging circuitry with USB-C power connector was added.

All of these - are currently testing in our lab! See the result below!

All the hardware is open source and is available on our GitHub repository. Schematic and PCB are currently designed in a free to use Circuit Maker environment (by Altium).

Main hardware components and features

PCB - Dual layer, Credit card size

MCU - ESP32-WROOM series

LoRaWAN SX1276 module with spring antenna

Mini GNSS module from uBlox/SimCom/Quectel (replaceable) with integrated antenna

Small 0.1” / 2.54 mm development area with power, ground and GPIOs; I2C interfaces

LED indicators

Battery power and charging circuitry

USB-C power connector

Test applications

I currently have two test devices running. One is transferring temperature and humidity data and another is dedicated to position tracking and sending latitude and longitude over the Helium network. Both data flows are decoded with by a simple script in the Helium console and then push data to online sheet (so called Google sheets integration)