feature-firmware/org.meshtastic.feature.firmware.ota.dfu/LegacyDfuTransport

LegacyDfuTransport

class LegacyDfuTransport : DfuUploadTransport(source)

Kable-based transport for the Nordic Legacy DFU protocol (Nordic SDK 11/12 / Adafruit BLEDfu).

Most nRF52 boards in the field — including the RAK4631 with the recommended Adafruit/oltaco "OTAFIX" bootloader — speak Legacy DFU rather than Secure DFU. The two protocols share nothing at the upload layer:

Different service & characteristic UUIDs (1530/1531/1532 vs FE59/8EC9…).
Different opcodes; init packet is sent on the Packet char between two control-point writes (vs Secure's CREATE/PACKET/EXECUTE object flow).
PRN payload is bytes-received uint32 (vs Secure's offset+CRC32).
No CRC32 in the protocol — image integrity relies on the device's CRC16 in the init packet.

Phase-1 buttonless trigger is shared with SecureDfuTransport (see triggerButtonlessDfu there).

Types

Companion

object Companion

Properties

isLowSpeedTransfer

open override val isLowSpeedTransfer: Boolean

Low-speed when the bootloader did not negotiate a larger MTU, leaving us on the 20-byte packet floor. Valid once connectToDfuMode has established the connection (the MTU is known by then).

Functions

abort

open suspend override fun abort()

Send RESET to the device, instructing it to discard any in-progress transfer and reboot. Best-effort — the device may disconnect before the write ACK lands; that's expected.

open suspend override fun close()

Disconnect and release resources.

connectToDfuMode

open suspend override fun connectToDfuMode(): Result<Unit>

Scans for the device in DFU mode (address or address+1) and establishes the GATT connection, enabling notifications on the Control Point.

transferFirmware

open suspend override fun transferFirmware(firmware: ByteArray, onProgress: suspend (Float) -> Unit): Result<Unit>

Drives the full upload sequence (START, init-packet brackets, PRN setup, firmware stream, validate, activate).

open suspend override fun transferFirmware(firmware: ByteArray, onPhase: suspend (DfuUploadPhase) -> Unit, onProgress: suspend (Float) -> Unit): Result<Unit>

As transferFirmware, additionally reporting coarse DfuUploadPhase transitions so the UI can explain a wait that produces no progress (Legacy DFU erases the whole application region before it accepts a single byte). Transports without a meaningful prepare step keep the default, which never reports a phase.

transferInitPacket

open suspend override fun transferInitPacket(initPacket: ByteArray): Result<Unit>

Sends the legacy DFU init packet using the SDK 7+ extended-init flow: