This is an old revision of the document!

Meshcore

Download the PDF version of this page.

Introduction

MeshCore is an open-source mesh networking protocol and software platform designed for off-grid, low-power text communication using LoRa (Long Range) radio technology. The system enables decentralized, multi-hop wireless messaging without reliance on cellular networks or internet infrastructure.

Use cases include emergency and disaster communications, outdoor and remote activities, [...] and experimental and educational deployments of low-power mesh networking.

[It] is designed to [...] operate in unlicensed ISM frequency bands such as 868 MHz and 915 MHz, depending on regional regulations.

The idea is that each person has a small companion device C paired to their cellphone via Bluetooth, and via that device, they can text each other or post public messages using the 915 MHz band, all without a special license. The signal can travel directly between companion devices if they are close enough, or via a series of repeaters R to extend coverage.

MeshCore devices used as companion.

A MeshCore device setup as a repeater.

Companions

¹⁾

What is needed to use MeshCore?

The MeshCore app downloaded to your cellphone or computer.
A device with the MeshCore companion firmware paired to your cellphone.
If needed, a device with the MeshCore repeater firmware to extend messaging range.

Each person who wants to send messages needs their own companion device.

Download the MeshCore App

Search for “MeshCore” by “Liam Cottle” on Google Play or the Apple App Store.
Alternatively, an offline copy can be downloaded for Android, Windows, MacOS, Linux, and Web from https://meshcore.io. It's a good idea to have an offline copy in case of emergency.

Where to buy MeshCore devices?

Recommended devices are listed at https://meshcore.io
Alternatively, supported devices listed on https://meshcore.io/flasher can be purchased online from overseas suppliers such as AliExpress or SeeedStudio, or in Canada from Robot Shop.

Flash the Firmware

Use a Chromium-based web browser like Brave.

On Linux, you may have to add the “dialout” group to your user. To do that, type the following in the terminal replacing “USER” with your username and reboot your computer:

sudo usermod -a -G dialout USER

If you already have Meshcore installed, backup your current settings:

Open the MeshCore app
Navigate to the Settings (the gear in the top right corner)
Scroll down to the “Extra Tools” section and select “Export Config”
“Select All” and click on the check mark in the top right corner to save the “.json” file to your phone.

Flash the Meshcore Firmware:

Connect the companion device to your computer via USB.
Go to https://meshcore.io/flasher (using a Chromium Browser).
Select your device
Select Companion Bluetooth
Select Enter DFU Mode
Select Erase Flash (for brand new devices only.)
Select Flash

To re-load your previous config file (required only if you lost your configuration for some reason).

Open the MeshCore App
Connect to the companion device, but it probably had a different bluetooth name now
Enter the PIN displayed on your MeshCore device’s screen. If your device doesn’t have a screen, the default pin is “123456”.
Skip Setup
Navigate to the Settings (the gear in the top right corner)
Scroll down to the “Extra Tools” section and select “Import Config”
Click on “Select File”
Select the “*.json” file
“Select All” and click on the check mark in the top right corner.

Connect to your MeshCore Device

Turn on your device.
Open the MeshCore App.
Tap the “Connect” button in the top right corner.
Tap the “MeshCore-XXXX” device that matches the name shown on your MeshCore device’s screen.
Enter the PIN displayed on your MeshCore device’s screen. If your device doesn’t have a screen, the default pin is “123456”.
Once pairing is successful, you’ll be taken to the main screen.

Tap “Connect” in the top right corner.

Tap “MeshCore-XXXX” which matches the name on your MeshCore device.

You are now connected!

If you’re having trouble pairing with Bluetooth, try rebooting your phone.

Settings

Tap the settings icon in the top right corner.

Quick Checklist:

Share Position in Advert
Use 2-byte Path Hash Size
Disable Auto Add of Contacts
Disable GPS Mode
Send a flooded advert

Public Info

You should now rename and set a location for your MeshCore node. These settings will be seen by other users on the MeshCore network (and online!) and can be changed anytime.

Write a name that is somewhat descriptive (your name or callsign).
Tap the map icon to pick your location. This will be shared online so you might want to select a street corner that's close to but not exactly where you live. It should be close enough to be useful for your neighbours to identify you as part of the neighbourhood.
Check the “Share Position in Advert”
Tap the ✔ icon in the top right corner to save the settings.

The device name in Bluetooth will not update until you reboot your node.

Radio Settings

MeshCore can be used all over the world. Different countries have different regulations on which radio frequencies can be used for public, license free communication. To ensure your node is operating legally, please make sure to select radio settings that are compliant in your country.

The MeshCore app provides a list of radio presets that have been suggested by the community for use in specific countries/regions, but in the SWBC region, we use different settings (see here for more details):

Tap Selected Preset field and select “Canada”. After you save, this will change to “Custom”.
Change the Frequency (MHz) to “909.000”
Make sure the other settings match the picture and tap the ✔ icon in the top right corner to save the settings.

The max transmit power depends on the device.

Network Settings

The Path Hash Size is a chunk of data that is sent with your messages to identify who you are on the mesh (kind of like your node's address). It is the first 1, 2, or 3 byte of your public key.

There's a trade-off between how many hops a message can go and how many unique addresses each hash size can have. When two nodes have the same path hash, messages can be routed to the wrong place.

Path Hash Size	Number of unique addresses	Max Hops	Recommended for
1-byte	256 (16²)	64	Avoid
2-byte	65536 (16⁴)	32	Companions
3-byte	16 millions (16⁶)	21	Repeaters

This page shows nodes with duplicate addresses, which can be fixed by increasing the path hash size.

Tap the “Default Path Hash Size” and select “2-byte” for companions, or “3-byte” for repeaters.
Tap the ✔ icon in the top right corner to save the settings.

Other Settings

In this section, we'll change two settings:

Contact Settings
Position Settings

Contact Settings

By default, the app adds every node it hears to the contact list, but it can only store 350 contracts. It's better to let the user add contacts manually:

Select “Auto Add Selected”
Uncheck all four options
Tap the ✔ icon in the top right corner to save the settings.

Position Settings

By default, the app can change your location based on your GPS coordinate. Since we've already set an approximate location earlier, we'll want to disable this option. It can be temporarily enabled if you're going somewhere you'd like others to be able to track you (for example).

Select “Disabled”
Tap the ✔ icon in the top right corner to save the settings.

Extra Tools

The last thing we'll do before exiting the settings is to backup all our configs:

Tap “Export Config”
“Select All”
Tap the ✔ icon in the top right corner to save the settings.

Finally, let's tap the ✔ icon in the top right corner one last time to save the settings before exiting.

Contacts

Unlike SMS, you can only send a private message to someone if you are both in each other's contact list.

In this section, we'll see four different methods of sharing contact information.

Add / Discover
QR Code
Link to Clipboard
In a Channel

1. Advert / Discover

An advert is an unencrypted packet transmitted by your MeshCore node. It includes your node name, location and type, public identity key and a cryptographic signature to prevent anyone from tampering with the information as it’s sent across the mesh.

You can send two types of adverts:

Zero Hop:

The advert won’t be retransmitted by any repeaters.
Your contact details will only be received by nearby nodes.

Flood Routed:

The advert will be rebroadcast by all repeaters that hear it.
Your contact details could be received by everyone on the mesh.

There was a deliberate decision made to prevent auto advert for companions (but not for repeaters). As such, you should flood advert at least once a week so that new users can find and add you to their contact list.

Tap of the “wave” icon just on the left of the gears at the top
Tap “Advert • Flood Routed”

The easiest way to add nodes that are in your neighbourhood to your contact list is to use the map feature. However, there are three different kids of maps in Meshcore:

1) The map at the bottom of the main page only shows nodes in your contact list.

2) The map under “Discover Contacts” shows all the nodes that your companion has heard so far.

3) The “Internet Map” shows a map of all the nodes heard by “observers” that are shared to the Internet.

Discover

To populate your contact list, use the “Discover Contacts” map (2). You might have to leave your node on for a bit for it to hear all the nodes in your area since they need to advert or transmit for your node to see them:

In the “Discover Contacts” → “Map View”
Tap on the filter icon and select “Users”.
Tap on ⋮ in the top right and uncheck “Show Added Contacts”

The map will only show users that have not been added yet. To add them:

Tap on a node
Under the node's name, tap on “Add”

If you go back to the main page's “Map” (1), you should now see that contact.

The maps only show nodes that have Shared their Position in Advert. Nodes that have not shared their location will still show in the list, but you won't be able to tell where they are located. That's why it's important to share your approximate location: so others in your neighbourhood can add you to their contact list.

2. QR Code

To share your contact details privately via QR Code:

Tap on ⋮ in the top right.
Tap the “My Contact Code” menu item.
Show the QR Code to the other person.

The QR Code contains your Node Name, Node Type and Public Identity Key. Your contact details will not be transmitted over the mesh. Only the person who scans your QR Code will receive your contact details.

Add

To add a contact via QR Code:

Tap on ⋮ in the top right.
Tap the “Add Contact” menu item.
Tap the “Scan QR Code” button.
If requested, grant access to the device’s camera.
Point the device’s camera at the QR Code.
The contact details will be automatically added to your contacts list.

You may need to accept a permissions request for the MeshCore app to access your camera. This permission must be granted to be able to scan the QR Code.

3. Link to Clipboard

The easiest way to share your contacts via email or SMS is to use a contact link.

Share

To share your contact link:

Tap on ⋮ in the top right.
Tap the “My Contact Code” menu item.
Tap on ⋮ in the top right.
Tap on “Copy Link to Clipboard”
Paste the link in an email or SMS

Add

To add a contact link:

Copy the contact link you were sent to your phone's clipboard.
In the Meshcore app, tap on ⋮ in the top right.
Tap on “Add Contact”
Tap on “Import from Clipboard Link”

4. In a Channel

Sending Messages

Public Broadcast

Messages sent to the Public channel can be seen by anyone on the MeshCore network. They are repeated across the mesh by all repeaters that hear them. Other mesh nodes in range of you or a repeater that rebroadcast the message, should receive it.

The public channel can be used as a large group chat for general conversation amongst all users on the mesh. It could also be used to send emergency alerts.

It’s not recommended to send confidential information on the public channel as anyone can read these messages.

To send a message:

Tap the channels tab at the bottom of the screen.
Tap the “Public” channel.
Type a message and press the send icon.

Tap the channels tab at the bottom of the screen.

Tap the “Public” channel.

Type a message and press the send icon.

Outgoing messages will show “Heard 1 repeat” if your node heard a nearby repeater passing on your message. If there are no nearby repeaters, it will show “Sent”. It’s not possible to know who received a channel message.

Private Messages

Once you’ve added a contact, and that contact has added you back, you can send private messages to each other across the mesh. These messages are encrypted and only the intended recipient can read the message contents.

To send a private message:

Tap the contact you want to send a message to.
Type a message and press the send icon.
The app will try several times to deliver your message to the recipient.
If it’s successful, it will show “Delivered” with a check mark.
If an automatic acknowledgement from the recipient is not received after some time, the message will turn red and show as “Failed”.
When messages are received, they will show up in the conversation viewer.

Tap the contact you want to send a message to.

Type a message and press the send icon.

Received messages will show up in the conversation viewer.

A message may get marked as failed even though it was successfully delivered to the recipient. This happens if we did not receive the acknowledgement reply from the recipient node. In this case, it’s recommended to send the message again. Once you see the delivered check mark, you know for sure it was received.

Retry Sending a Failed Direct Message

When you send a direct message to someone, it’s possible that it may not go through after several automatic attempts. This can happen for many different reasons, such as:

Being out of range of the intended recipient.
There are no repeaters in between you and the intended recipient.
The intended recipient’s radio might be turned off.
There might be interference on the radio spectrum.

To try sending the failed message again:

Long press the failed message shown in red.
Tap the “Retry Sending” button shown in the message actions popup.
Your message will try sending again.

Long press the failed message shown in red.

Tap the “Retry Sending” message action.

Your message will try sending again.

When sending direct messages, you must both add each other as contacts first. The recipient's companion radio must be turned on to receive the message and to provide a delivery report. You must also be in radio range of each other, or have a working path of repeaters between each other.

Ping a Repeater

To check the signal strength to and from a nearby repeater, you can run a ping test.

Tap on ⋮ icon next to a repeater contact.
Tap the “Ping (Zero Hop)” menu item.
A green popup will show signal strengths if successful.
A red popup will show “Timeout” if your companion didn’t hear the repeater.

Tap on ⋮ icon next to a repeater contact.

Tap the “Ping (Zero Hop)” menu item.

A green popup will show signal strengths if successful.

Ping tests do not hop through multiple repeaters. You must be in range of the specific repeater you are ping testing. For a ping test to be successful, the repeater must hear your companion signal directly, and your companion must hear the repeater signal directly. If you’re not in range of the repeater, the ping test will fail with a timeout error.

Repeaters

Install a repeater like the SenseCAP Solar Node P1-Pro from seeed studio or RobotShop
Use an antenna like this one, this one or one of these.

Installing the Bootloader for the First Time.

This step is required to be able to perform future updates over-the-air (OTA) via bluetooth, but is not required (or compatible) with esp32 devices like the Heltec V or T beam.

If you already have Meshcore installed (but not the bootloader), download your current settings:

Go to https://config.meshcore.io/
Connect your device to your computer with a USB cable.
Click on Connect
Click on Export
Click on Disconnect
Locate the .json file (probably in your Downloads folder).

Download the bootloader:

Go to https://meshcore.io/flasher
Select your device
Select Repeater (or Room Server)
Click on Download
Select the *bootloader-x.x.x-OTAFIXx.x.uf2 file
Locate the .uf2 file (probably in your Downloads folder).

Copy the bootloader over to your device:

Connect your device to your computer with a USB cable.
Double click on the reset button.
Open the drive that just mounted on your computer
Copy the .uf2 file to the drive.
The drive may close on its own right away. This is normal.