Easy firmware updates over LoRa

This guide shows the shortest manual path for sending firmware from a computer to a MeshCore node over LoRa. Choose the package type for the destination node:

For an end-to-end controller that accepts a release ZIP or ready mOTA, see Scripted LoRa OTA from start to finish.

Destination	Update type	Files needed to build the .mota	Installer
ESP32	Full firmware	New non-merged application .bin	ESP32 A/B firmware slots
nRF52, internal staging	In-place delta	Exact running firmware.hex and new firmware.hex	Exact-board OTAFIX bootloader
Supported nRF52 QSPI repeater	Full firmware or in-place delta	New firmware.hex; a delta also needs the exact running firmware.hex	Matching QSPI-aware OTAFIX bootloader
MeshTower V2 SD target	Full firmware or in-place delta	New firmware.hex; a delta also needs the exact running firmware.hex	Matching SD-aware OTAFIX bootloader

An internal-staging nRF52 target accepts only an in-place delta built against its exact running firmware. Matched QSPI repeater targets and the MeshTower V2 microSD target can also install a full image because the complete container stays off-chip. See nRF52 repeater OTA with external QSPI and MeshTower V2 microSD LoRa OTA.

MeshTower V2 microSD application and bootloader containers must be Ed25519-signed by a key in the device allowlist; pass --sign to motatool build (or --sign-key to the end-to-end runner) when building one. Its BLM2-capable SD-aware bootloader is also required before ordinary application or bootloader OTA can use the reset-retained authorization record. Upgrade preview.12 locally over USB/BLE DFU or SWD first; there is no raw-card compatibility handoff.

Temporary OTA channel used in this guide

Setting	Value
Center frequency	909.950 MHz
Bandwidth	250 kHz
Spreading factor	SF5
Coding rate used in this guide	CR5
Example window	120 minutes

The copy/paste command is:

tempradio 909.950,250,5,5,120

The fourth value is the transmit coding rate. This guide uses CR5, but the participating nodes' coding rates do not need to match.

tempradio is not saved and the node returns to its normal radio settings when the window ends or the node reboots. Current full-parser firmware also accepts normalradio, which cancels the temporary window and restores the saved tuple after replying on the current channel. This frequency is intended for North American configurations. Confirm that it is permitted in your location and change it when necessary.

At SF5/BW250, an SX1262+TCXO destination can keep RXPS enabled only when it and every sender that can reach it (controller, source, and relays) follow the v1.17.1.5-or-newer adaptive-preamble contract. The qualified destination boundary is effective level 8, preamble 64 and 1252 / 6424 us. For manual setup, save set radio.rxps level 8 preamble 32 before entering TempRadio; the 32 is a conservative saved timing assumption and current firmware selects the real 64-symbol wire preamble when it retunes the temporary radio. For an older, unknown, or mixed-version path, use set radio.rxps off for the maintenance window. First record get radio.rxps.config; after normalradio, restore a reported level with set radio.rxps level N preamble P (omit preamble P when P is 0). A legacy node returns only on/off and periods, which can be restored with set radio.rxps RX_US SLEEP_US. The scripted runner performs the version checks, temporary change, verification, and restoration automatically while preserving automatic retuning. SF5/BW500 is too fast for RXPS even with a 64-symbol preamble, so current firmware selects 128 and uses the qualified level-8 626 / 6398 us timing when every participant supports the adaptive contract.

Before you start

Both paths require:

• A destination artifact explicitly identified by its release table as install-capable. Some lean internal nRF52 builds carry lora_ota_no_external_sensors in the filename, while matched QSPI boards enable install support in the normal full-sensor repeater artifact, so filename text alone is not authoritative. Confirm support with ota self and ota status. Intermediate repeaters do not need an install-capable build: current repeater firmware relays OTA packets opaquely without storing or installing them.
• An OTA-enabled MeshCore source connected to the computer by USB serial, or an ESP32 WiFi companion/FULL source connected over WiFi as described below.
• Overlapping tempradio windows on the source, destination, and every repeater needed between them.

LoRa OTA packets are generated, consumed, and relayed only while tempradio is active. Intermediate repeaters apply their normal forwarding filters, duplicate checks, and flood limits; they do not interpret the OTA payload. If any required window closes, the transfer stops making progress and can resume during a later overlapping window.

build.sh provides a *_repeater_lora_ota_no_external_sensors build for standalone ESP32 and nRF52 repeater targets that need a smaller internal update workspace. Those siblings omit selected optional environmental and ranging drivers while retaining board-native features such as displays, buttons, battery monitoring, and GPS where the target uses the GPS-preserving lean profile. RAK3401 and RAK4631 reduced builds also retain INA219, INA226, INA260, and INA3221 I2C voltage/current monitors; together these drivers cost less than 5 KiB in the measured profile. Those four monitor drivers are not the only retained I2C support: the board's SSD1306 OLED, supported autodiscovered RTCs, and the RAK12500 GPS remain separate I2C peripherals in GPS-compatible RAK recipes. RAK12501/L76K GPS instead uses UART Serial1. The RAK3401 OTA repeater supports either GPS module in sensor slot A; slot D conflicts with the RAK13302 radio's BUSY/DIO1 lines. The RAK4631 OTA repeater defaults its runtime RS-232 bridge to Serial2 so the UART RAK12501 can retain Serial1. The runtime guard always reserves Serial1 because a bounded silent probe cannot prove a cold RAK12501 is absent; the shared WB_IO2/3V3_S rail keeps a fitted module powered and driving the UART. Use Serial2. Serial1 requires an explicit no-GPS/dedicated image. The merged image remains fail-closed even when it detects an I2C RAK12500. The explicit legacy Serial1 bridge omits the combined GPS provider, including the otherwise non-UART RAK12500 path.

The firmware-configured INA3221 address and the RAK12500 address are both 0x42; they cannot coexist on one bus at those addresses. Keep RAK12500 at 0x42, strap INA3221 A0 to SCL for 0x43, and use a build with -DTELEM_INA3221_ADDRESS=0x43 when both are installed.

Selected nRF52 boards with matched external QSPI application and bootloader support can instead make the normal full-sensor repeater install-capable; those targets do not need to reserve internal flash for the downloaded container. SolarXiao 30S and 33S use this matched external-QSPI path and therefore do not emit redundant no-external-sensors siblings. Other normal repeaters can still serve as intermediate relays but cannot necessarily install an update themselves. ESP32 -ota- siblings also retain the lightweight browser WiFi uploader (start ota), the complete CLI, and a 254-entry neighbor table. RP2040 and STM32 repeaters do not currently have a safe self-apply path, but current repeater firmware can still relay OTA packets opaquely during TempRadio.

For one explicitly selected internal-flash nRF52 repeater, the default --build-profile auto run emits two install-capable choices. The *-full-ota-* artifact retains external sensors, while the *_lora_ota_no_external_sensors-reduced-ota-* artifact trades only those optional drivers not explicitly retained by the board profile for more delta-staging space. They retain the same OTA target identity so update tooling does not confuse the optimization choice with a different board. QSPI- and SD-backed repeaters emit only the complete choice unless a measured size failure requires a fallback.

nRF52 -ota- siblings are compiled with size optimization instead of the Adafruit platform's default speed optimization. This prevents the retained software Ed25519 fallback from expanding beyond the fixed in-place workspace; CC310 hardware crypto, hardware RNG mixing, telemetry history, and board-native features remain enabled.

ESP32 *-full-usb-wifi-ota-* artifacts retain all compiled features and enable LoRa OTA for every FULL role, including room servers, sensors, observers, and bridges. A FULL image requires its expanded partition table: install the matching merged image over USB once before installing later non-merged FULL updates over LoRa. ESP32 MQTT observers and ESP-NOW bridges are always emitted as FULL artifacts; compact-CLI variants are no longer built. The *-full-usb-wifi-ota-* profile compiles USB packet logging and direct WiFi MQTT into one image. Use set logging.output off|usb|wifi|both to persist the desired path. A *-full-logging-ota-* artifact is now only a fallback for a hardware/role combination without a WiFi MQTT target and can produce substantial serial output.

Choose the source radio

Use an OTA-enabled MeshCore node as the source. It receives the update folder from the computer, then advertises it over LoRa. ESP32 USB/WiFi companions and FULL ESP32 roles include the required transport. A *_companion_radio_full target keeps only the source half of LoRa OTA: it serves host images but cannot stage or install one for itself. ESP32 full combines USB, BLE, and WiFi; nRF52 full combines USB and BLE because nRF52840 has no WiFi. A small set of high-capacity, non-PSRAM classic ESP32 companions keep their normal image and provide a separate -full-logging-ota- fallback with 100 contacts, 8 group channels, a 16-frame offline queue, and persistent USB output selection. Install that variant's merged image over USB once before using it. Connect the source by USB serial or, when supported, by WiFi. For an ordinary raw-text USB source, confirm that its USB CLI accepts:

ota folder on

If an older build reports that OTA_FOLDER_SERIAL is not compiled in, install a current -ota-, -full-usb-wifi-ota-, or applicable -full-logging-ota- build first. Do not use a KISS modem: KISS firmware is a TNC/KISS frame interface and does not provide the MeshCore CLI or the OTA-folder transport that motatool serve requires.

An nRF52 companion_radio_full starts in its USB ASCII terminal and automatically changes to Binary Companion when it receives a complete < frame. It also recognizes motatool's exact initial ota folder on line and enters exclusive mOTA mode directly, so motatool serve --serial can be the first client after boot. No terminal token or preliminary disconnect is required. Stopping the tool or disconnecting resets USB to Binary. BLE remains available throughout. See the Full Companion USB switcher guide for the complete ownership transitions. Protocol v14 can instead take the catalog from a paired phone or Linux host over a separate encrypted BLE mOTA service while Binary Companion remains active. USB and BLE catalog sources are mutually exclusive. See the Full Companion Bluetooth source guide.

For an ESP32 WiFi companion or FULL ESP32 source with active WiFi, use its dedicated OTA seeder:

motatool serve --dir ./motas --tcp <source-host>:5001 -v

Port 5001 is separate from the companion application port (5000) and the HTTP configuration/browser-OTA port (80, depending on the role). An ESP32 companion_radio_full also has its complete role-specific text terminal on port 5002; OTA automation uses its ota and TempRadio subset. See the full Companion guide. On a FULL repeater or room server, start webconfig can bring up the saved WiFi connection. Other FULL roles with browser OTA support can raise MeshCore-OTA with start ota and use 192.168.4.1:5001. The TCP seeder auto-attaches; do not also run ota folder on for USB serial.

Install motatool

Install Rust if necessary, then install the standalone packaging and serving tool:

git clone https://github.com/vk496/motatool
cargo install --path ./motatool

ESP32: package a full firmware image

The destination must be an OTA-capable ESP32 with an A/B partition table. Download or build the new non-merged .bin application for the destination's exact board and role. Do not use an ESP32 -merged.bin factory image.

Put the application firmware in a working directory, then build a full .mota container. For example:

mkdir -p ./motas
motatool build --fw ./Heltec_v3_repeater-ota-v1.16.05.bin --out-dir ./motas
motatool verify ./motas/*.mota

Replace the example filename with the firmware for the destination's exact target. With no --base argument, motatool build creates a full-image update. The firmware must contain its MeshCore EndF identity trailer so motatool and the destination can verify the target, hardware, and version.

Do not continue if motatool verify reports a failure.

nRF52: package a full image or in-place delta

1. Install and check the OTAFIX bootloader

This is a one-time prerequisite. Install the OTAFIX bootloader built for the destination's exact board from the OTAFIX nRF52 bootloader releases. Internal-staging delta updates require OTAFIX 2.4 or newer. External QSPI and SD staging require OTAFIX 2.4.1 or newer and release notes that explicitly list the exact board and storage mode. Follow the release's board-specific installation and erase instructions. If it does not contain the destination's exact board, this LoRa install path is not yet available for that board; never substitute a similar board's bootloader.

Before preparing or downloading a LoRa update, run this on the destination:

get bootloader.ver
ota self

The first command identifies the installed nRF52 bootloader. Continue only if the ota self reply includes the apply mode required by this target:

bootloader: apply OK
bootloader: QSPI apply OK
bootloader: SD apply OK

The reply also contains the running firmware's base_hash. Save it for the package check below. A stock, legacy, or older OTAFIX bootloader without .mota in-place-apply support will report that apply support is missing, and ota install will refuse to reboot into it.

2. Choose full or delta packaging

For a QSPI- or SD-backed target, a full update needs only the new raw firmware.hex:

mkdir -p ./motas
motatool build --fw ./LilyGo_T-Echo_repeater-new.hex --out-dir ./motas
motatool verify ./motas/*.mota

Use a full package when an exact base image is unavailable. Use the delta path below when reducing airtime is worth retaining the exact running image.

3. Keep the exact current and new application images for a delta

You need the raw .pio/build/<environment>/firmware.hex from the build that is actually running, plus the corresponding firmware.hex from the new build. Save the current file before building the new version, because PlatformIO reuses that path. For example:

# Save this immediately after building/flashing the version now running on the node.
cp .pio/build/Heltec_t114_repeater_lora_ota_no_external_sensors/firmware.hex \
  ./Heltec_t114_repeater_lora_ota_no_external_sensors-running.hex

# After checking out and building the new version, save its image separately.
cp .pio/build/Heltec_t114_repeater_lora_ota_no_external_sensors/firmware.hex \
  ./Heltec_t114_repeater_lora_ota_no_external_sensors-new.hex

Replace Heltec_t114_repeater_lora_ota_no_external_sensors with the destination's exact PlatformIO environment. The two images must be for the same board and role, and both must contain their EndF trailers. Do not pass a release .uf2 or BLE-DFU .zip to motatool; those are installation containers rather than raw application images.

Keeping a file with the same version label is not enough: the base must be byte-for-byte identical to the running application. The hash check in the next step proves that it is the right file.

On RAK4631 repeaters, use the RAK_4631_repeater_lora_ota_no_external_sensors environment. It retains built-in battery monitoring but omits selected optional environmental/ranging drivers so the delta fits the safe in-place workspace. INA219, INA226, INA260, and INA3221 I2C voltage/current monitors remain supported despite the legacy target name. That trim does not remove the SSD1306 OLED, autodiscovered I2C RTCs, or GPS-compatible RAK12500 I2C path. The 0x42 RAK12500/INA3221 addressing rule above still applies. If the device has a RAK15001 installed in sensor slot C and the matching RAK15001 OTAFIX bootloader, use RAK_4631_repeater_rak15001_slot_c_lora_ota instead. That target retains the full sensor/GPS set and can install either a full image or a delta from the external 2 MiB store.

4. Build and check the in-place delta

mkdir -p ./motas
motatool build \
  --base ./Heltec_t114_repeater_lora_ota_no_external_sensors-running.hex \
  --fw ./Heltec_t114_repeater_lora_ota_no_external_sensors-new.hex \
  --patch-type in-place \
  --out-dir ./motas
motatool verify ./motas/*.mota

motatool prints the generated filename. Inspect that file:

motatool inspect ./motas/GENERATED_FILENAME.mota

Check all three of these before serving it:

• codec_id is 2 (detools-in-place).
• base_hash is the same 8-byte value reported by the destination's ota self command.
• The numeric target_id exactly matches target: in the destination's ota status, and the hardware and firmware version identify the intended board and role. If inspect shows N/A for the human-readable target name, the tool's name table is older than that environment; the numeric IDs still must match.

Current layout-aware motatool derives the safe workspace from the new firmware's authenticated EndF layout record, so the normal recipe deliberately omits --inplace-memory. If older tooling requires an explicit override, use 0xC6000 only for matched external SD/QSPI staging and 0x98000 for an internal-staging nRF52 such as the RAK4631 lean OTA build. Do not substitute the external value on an internal target, and do not override either value unless you have verified the exact app base, bootloader, and package geometry. Do not continue if verification or any identity check fails.

Transfer and install either package

1. Start the temporary OTA channel

First save the current ota config output. For a direct source-to-destination link, set both OTA-enabled endpoints to direct-only mode before starting the transfer:

ota config hops 0

Do not use hops 1 as extra margin on a direct link. It tells a receiving repeater to retransmit each direct DATA/PROOF packet; that unnecessary half-duplex transmission can make it miss the source's next fragment, especially with older single-block receivers. Use hops 1 only when one real intermediate relay is required, hops 2 for two, and so on. This setting is saved, so restore the original value after the maintenance window.

On the source node, destination node, and every intermediate repeater, then run:

tempradio 909.950,250,5,5,120

All participating nodes must use the same frequency, bandwidth, and spreading factor. Their time windows must overlap. Start with the farthest hop (the destination) and work back toward the source when using tempradio.

If you administer the destination over LoRa, the controller used to send later ota commands must also be able to communicate on this temporary channel. For unattended nodes, use synchronized tempradioat entries instead of manually starting the windows. Ensure the nodes' clocks are set before using tempradioat.

2. Serve the update from the computer

Close any serial terminal using the source node's USB port, find its device name, and start the server:

motatool serve --dir ./motas --serial /dev/ttyACM0 -v

Replace /dev/ttyACM0 with the USB serial device of the source companion selected above. motatool attaches the folder to the source, which advertises the update over LoRa while its temporary-radio window is active. KISS modem serial ports cannot be used here.

For an nRF52 Full Companion and a Bluetooth-capable host, the equivalent cable-free source is:

python3 tools/ble_mota/ble_mota_seeder.py \
  --device MeshCore-MyCompanion \
  --dir ./motas \
  --local 'tempradio 909.950,250,5,5,120'

Leave this command running until the destination finishes downloading.

3. Find and download the update

On the destination node, check its state and ask for nearby updates:

ota status
ota ls

Discovery is asynchronous. ota ls says refreshing; wait a few seconds and run it again even if it first shows an older row. Select [same target]: it can say full for ESP32 and external SD/QSPI nRF52 targets, or delta for any supported nRF52 target. Do not select [unsupported] (for example, a source's self-served full image on an internal-staging nRF52). Rows labelled bootloader are also outside this ordinary application flow: they are never automatic and ota install refuses them. Only an already-capable, allowlisted internal-flash, XIAO-QSPI, or exact MeshTower V2 microSD nRF52 target can use the separate explicit bootloader workflow. Use the row's stable eight-hex manifest ID rather than its changing list position:

ota pull 838B8169 flash

If a legacy internal-flash nRF52 reports no EndF, only a row marked [rescue] is eligible. Current rescue-capable firmware requires ota pull <mid8> flash rescue, followed after completion by ota rescue install <base_hash16>. Older running firmware without those commands must be recovered over USB. Shared-internal bootloader-update builds are stricter: without a valid live EndF, every internal pull is refused before erase because the normal application may extend through 0xED000. Recover those builds over USB/BLE DFU or SWD instead of relying on the older 608 KiB rescue estimate.

Monitor the transfer:

ota status

For a powered bench update where restart-resume is not needed, ota config checkpoint 0 on the destination removes periodic progress writes. It is a smaller optimization than selecting the correct hop count and it trades away persisted mid-download resume; restore the previous checkpoint cadence afterward.

Current repeater firmware automatically uses the full transmit budget during a bounded TempRadio window. Older receivers do not: if get af reports a nonzero value on such a node, record it, use set af 0 for the maintenance window, and restore it afterward. This affects how promptly the legacy receiver can send its next block/proof request; it does not increase LoRa transmit power. Use a full duty budget only where the selected frequency and local rules permit it.

The update is ready when the status says ready to install. Discovery is background traffic, while an active OTA download is primary mesh traffic. At the temporary-radio settings in this guide, allow roughly one hour for a typical ESP32 full image over a quiet, direct link. That is a planning estimate, not an upper bound: repeaters, retries, weak links, and normal mesh traffic can extend it well past an hour. The 120-minute example window is intentional. If necessary, start another overlapping tempradio window; the download resumes rather than starting over.

4. Verify and install

Once the destination reports ready to install, run:

ota install

The destination verifies the complete package again before approving it. ESP32 installs the full image into its inactive A/B slot. nRF52 checks the bootloader and storage capabilities and, for a delta, the base hash, then reboots into OTAFIX. The bootloader independently rechecks the package, installs the external full image or applies the delta in place, and verifies the resulting image. Pre-install failures leave the running firmware unchanged and report the reason. If power is lost after an nRF52 in-place apply has begun, OTAFIX will not boot a partial image; it enters recovery DFU so a known-good application can be restored.

After the node returns, reconnect on its normal radio channel and confirm:

ota status

Quick troubleshooting

• Nothing appears in ota ls: confirm that motatool serve is still running and every required node has an active tempradio 909.950,250,5,5,120 window.
• The CLI says LoRa OTA is not included: that firmware does not contain the LoRa OTA feature. If it is the source or destination, install a supported -ota- build over WiFi or USB first. An intermediate repeater does not need the OTA CLI and can relay opaquely while its matching tempradio window is active.
• The update shows another environment or a raw [hw XXXXXXXX]: it is for a different board or firmware role. Do not install it.
• An internal-flash nRF52 marks a full update [unsupported]: it can install only an in-place delta. A matched QSPI repeater or MeshTower V2 microSD target accepts full images with its corresponding bootloader.
• A QSPI nRF52 reports QSPI store:ERR 0K or bl:NO-QSPI: do not download an install package. Install the exact QSPI-aware bootloader and check that the selected application matches the board's flash wiring.
• nRF52 reports no bootloader apply support: install the exact-board in-place-delta OTAFIX bootloader before trying LoRa OTA.
• nRF52 reports a base mismatch: the file passed to --base is not the exact application running on the destination. Rebuild the delta from the correct saved firmware.hex.
• The download stalls: check the source, destination, and intermediate repeaters. Restart matching, overlapping temporary-radio windows if one expired. On a direct link, also require ota config hops 0; a larger reach makes a repeater destination unnecessarily echo source packets.
• The serial port is busy: close the serial terminal before starting motatool serve.
• The destination rejects the package: verify the source files, their EndF trailers, the package's target/hardware identity, and the result of motatool verify.

For additional commands and safety details, see the full OTA user guide. For protocol and container internals, see the OTA protocol specification.