# MeshCore Firmware Variants Explained *Accurate as of 13 July 2026. Firmware version numbers below should be checked against the current releases before you rely on them.* MeshCore is built in several distinct firmware types, each designed for a specific role in the mesh. Choosing the right one matters: the roles are not interchangeable, and a node flashed as a Repeater cannot be used as a personal messenger. **This page covers node roles.** On this page, "variant" always means *role*. There is a second, separate choice: which *distribution* you flash. Stock MeshCore is one option, and several independent projects (EasySkyMesh, Keymind Cascade, MCLite, WADAMESH, ZephCore) build their own MeshCore firmware with different priorities. See [MeshCore Firmware Distributions](https://wiki.meshamerica.com/books/meshcore/page/meshcore-firmware-distributions). Pick a distribution first, then a role within it. ## The Firmware Variants ### Companion The Companion firmware is for user-facing nodes. It is what you run on your personal device to send and receive messages through the MeshCore mobile app. - **Primary function:** Sends and receives direct messages and channel (group) messages. Maintains a contact list. Connects to the MeshCore mobile app. - **Three builds, not two.** BLE Companion and USB Serial Companion are both prebuilt by the official flasher. A **Wi-Fi Companion** build also exists, but the official flasher does not ship it, because the Wi-Fi SSID and password are compiled into the binary. You either build it yourself or take a prebuilt one from a fork (Keymind Cascade prebuilds Wi-Fi companion binaries). - **When to use:** Personal handheld nodes, [base station nodes](https://wiki.meshamerica.com/books/hardware-guide/page/base-station-nodes) used for human communication, any node a person interacts with via the app. - **Firmware file example:** `Heltec_v3_companion_radio_ble-v1.16.0-07a3ca9.bin` (or the corresponding `..._companion_radio_usb-...` build; RAK4631 nRF52840 boards ship a `.uf2` companion build) ### Repeater The Repeater firmware turns a node into dedicated mesh infrastructure. It has no user interface and no messaging capability of its own. **A MeshCore repeater is not a repeat-everything flood relay.** This is the single most common misunderstanding, and it is MeshCore's main architectural difference from other LoRa mesh systems. Upstream's FAQ puts it in bold: a MeshCore repeater "does **not** forward or retransmit every packet it receives, unlike other LoRa mesh systems." - **How it actually works:** MeshCore floods a packet only while it is discovering a route. Once a path is known, packets carry that path, and *only the repeaters named in the path* retransmit them. See [MeshCore Routing: Flood-First, Direct-Route-After](https://wiki.meshamerica.com/books/meshcore/page/meshcore-routing-flood-first-direct-route-after). - **No Bluetooth.** You cannot connect to a node running Repeater firmware over Bluetooth. It is administered over USB serial, or remotely over the air. - **When to use:** Any node whose sole purpose is extending mesh coverage. Hilltop repeaters, building relays, infrastructure backbone nodes. - **When NOT to use:** Do not flash Repeater on a node you intend to use as a personal communicator. It has no user-facing messaging. - **Firmware file example:** `Heltec_v3_repeater-v1.16.0-07a3ca9.bin` (RAK4631 nRF52840 boards ship a `.uf2` repeater build) ### Room Server The Room Server firmware creates a store-and-forward message room. It works like a small BBS or persistent group chat reachable over LoRa. - **Primary function:** Clients log in to the room and post messages. The server stores the room's posts and pushes recent unseen ones to a client when it next connects, so you can catch up on what you missed while offline. - **Scope, precisely:** it stores *that room's* posts, and it pushes a limited backlog (upstream currently pushes the last 32 unseen posts on login). It is not a network-wide message archive and it does not store other people's direct messages. - **When to use:** Fixed infrastructure serving as a community message hub, in a building, on a hilltop, or at an event site where a persistent group thread is useful. - **Firmware file example:** `Heltec_v3_room_server-v1.16.0-07a3ca9.bin` (RAK4631 nRF52840 boards ship a `.uf2` room\_server build) ### GUI For boards with a screen, the official flasher builds GUI firmware (and a GUI-with-SD-card variant). A GUI node is a Companion with an on-device interface, not a separate network role: it messages and it does not relay. ### KISS Radio A KISS TNC build. It turns the node into a plain modem driven by a host computer, rather than a participant in the mesh in its own right. See [MeshCore KISS Modem Protocol](https://wiki.meshamerica.com/books/meshcore/page/meshcore-kiss-modem-protocol). ### Sensor: read this carefully Sensor firmware is the most misunderstood item in this list, so be precise about what exists. - The upstream MeshCore repository contains a `simple_sensor` example application. **The source exists.** - **The official flasher does not build it.** The flasher's role list is Companion (BLE), Companion (USB), Repeater, Room Server, GUI, GUI-with-SD, and KISS. There is no Sensor entry, and the upstream releases contain no sensor binaries. You cannot flash a stock Sensor build from [flasher.meshcore.io](https://flasher.meshcore.io). - To get a prebuilt Sensor binary you either compile it yourself or take one from a fork. [Keymind Cascade](https://wiki.meshamerica.com/books/meshcore/page/meshcore-firmware-distributions) ships Sensor builds for roughly 17 boards, and they are flashable from the Mesh America Device Configurator. - Sensor readings are **not** broadcast in adverts. A MeshCore advert announces a node's presence, not its telemetry. Sensor data moves over MeshCore's request/response protocol. See [MeshCore Sensor Nodes](https://wiki.meshamerica.com/books/iot-sensors/page/meshcore-sensor-nodes). ## Summary Table
RoleMessagesRelays for othersStores messagesPrebuilt by official flasher
Companion (BLE / USB)YesNoIts own onlyYes
Companion (Wi-Fi)YesNoIts own only**No** Self-compiled, or from a fork
RepeaterNoYes, along known paths. Not everythingNoYes
Room ServerNoNoYes, that room's postsYes
GUIYes, on deviceNoIts own onlyYes, on screen-equipped boards
KISS RadioNo, host-drivenNoNoYes
SensorNoNoNo**No** Source is upstream; binaries from forks or your own build
*Sources: the official MeshCore flasher catalog (flasher.meshcore.io), the MeshCore FAQ, and the firmware repository at github.com/meshcore-dev/MeshCore.*