Hardware

Tern runs on small LoRa boards of the kind Meshtastic and MeshCore use: 16 of them, from Heltec, LilyGo, RAKwireless and Seeed, and the flash page offers every one. So far one has been checked on hardware: Heltec WiFi LoRa 32 V3. The rest are built from their makers' documents and wait for someone to try one.

Choosing a board

• The surest: a Heltec WiFi LoRa 32 V3. It is the board Tern is checked on, and it costs little. Any other in the table works the same way if its pins are right, and trying one is how it gets checked.
• The right band. Every region Tern has is in 863 to 928 MHz: buy that version, not the 433 or 470 MHz one.
• An antenna, fitted before it is powered. The one sold with the board is fine to start.
• A screen and a button to see and use the node without a phone. A board without one works, with an app.
• A battery if it is to be carried: most of these boards take a single 3.7 V lithium cell and charge it over USB. An nRF52840 board runs for days on a cell where an ESP32 runs for hours.

Every board

Checked means someone has flashed a release onto one and checked it: the radio, the screen, the battery, the button and a message both ways. Not yet checked means the firmware is built for it on every change, from its maker's documents, and the release has its images, but nobody has yet said it works. It may well; if you try one, say how it went, and it becomes checked.

This follows the firmware's board list, which also says what each board in waiting is waiting on.

Flashing each kind

ESP32 boards: from this site, over USB

The flash page writes the release over USB from Chrome or Edge, with nothing to install, and can update a board that runs Tern already without losing its address. After that, the phone apps update it over Bluetooth. Every image is also in the release, to write with Espressif's tools.

nRF52840 boards: copy a file

The flash page gives you the board's .uf2 for your region. Plug the board in and press its reset button twice, quickly: it shows up as a USB drive. Copy the file onto it; the board writes it and restarts. Its bootloader stays, so going back to other firmware is copying another file on. These boards are not yet updated over Bluetooth: copy the next release on the same way.

A board the release has no image for

Every change to the firmware is built for every board, and each build's images are kept with it on GitHub, under Artifacts. Or build it yourself: the ESP32 and nRF52840 ports each say how.

What comes next

Most boards Meshtastic and MeshCore run on fall into a few families of chip and radio, and the firmware is brought up a family at a time: more ESP32-S3 and nRF52840 boards, LR1110 and LR1121 radios (driven, waiting for a board), then the RP2040, the STM32WL and a Raspberry Pi with a LoRa hat. A board's pins come only from its maker's own documents, so some wait on a maker to publish a detail. The firmware's board list keeps the plan.