Introduction

Build the other two MeshCore node types - a room server and a sensor node

Ahoy there makers! In part one we built a repeater and a client, and got a message across town for about £30. That course covered conversation. This one covers the other two things a mesh can do: remember, and measure.

Overview

MeshCore has four roles. You have already built two of them:

The problem with a plain mesh is that it has no memory. If you were out of range when a message was sent, you missed it - permanently. A room server fixes that: it holds recent posts and hands them over when you come back into range.

The other gap is that a mesh only carries what a human types. A sensor node fills that in: a board in a greenhouse, on a water tank, or at the bottom of a field, answering questions about the physical world across kilometres with no WiFi and no subscription.

Course Content

• What room servers and sensor nodes add to a mesh, and when each is worth building
• The hardware for both, including which sensors MeshCore actually supports
• Flashing and configuring a room server
• Admin passwords, guest passwords and read-only access
• Joining a room from the app, posting, and catching up on what you missed
• Permission tiers, access control lists and moderating a shared room
• Powering a room server, and the one mistake that will lose all your posts
• How MeshCore’s pull-based telemetry works, and why it is so power-efficient
• Flashing a sensor node and letting it auto-detect what you have wired up
• Building a BME280 environment sensor for a greenhouse or loft
• Reporting battery and solar voltage from a remote node
• Contact and level sensing - what works out of the box, and what needs custom firmware
• Requesting telemetry from your phone and reading what comes back
• Troubleshooting both node types
• Bridging telemetry out to MQTT, Home Assistant and Grafana

Key Results

After completing this course, you will:

• Have a working room server your local group can post to and catch up on
• Understand MeshCore’s three permission tiers and how to apply them
• Have a working sensor node reporting real environmental data over LoRa
• Be able to request and interpret telemetry from any node in your mesh
• Know how to power both node types for long unattended runs
• Be able to get mesh telemetry into Home Assistant or Grafana

What you’ll need

Prerequisite

• Off-Grid Messaging with MeshCore - part one. This course assumes you have a working repeater and client, that your radio settings are already correct for the UK, and that you know how to reach a serial console

Hardware

• 1 or 2 more Heltec WiFi LoRa 32 V3 boards, 868MHz (around £15 each) - one per role you want to build
• An 868MHz antenna for each new board
• A BME280 breakout for the environment build (around £5)
• Optional: an INA219 or INA3221 breakout for proper battery and solar current monitoring
• Optional: a VL53L0X distance sensor for tank level
• Dupont jumper wires, four per sensor
• A USB-C data cable

Skills

• Still no soldering strictly required, though a soldered header is far more reliable than a push-fit one
• Still no programming required, unless you take the custom firmware route in lesson 13

How the course works

Same as part one. Commands typed into a node’s console look like this:

set guest.password hedgehog

Values you change for your own setup appear in angle brackets, like set name <your-room-name>.

Every lesson has a Try it Yourself section and most have Common Issues. Let’s get building.

Next >

You can use the arrows  ← → on your keyboard to navigate between lessons.