Flash from an SD card
For field service, where there is no laptop and no USB cable — just the board and a prepared microSD. You make a bootable card once, and reflashing a device becomes "insert card, power on, wait."
This complements USB flashing: USB is the bench method, SD is the field method.
The idea
A bootable SD card carries the firmware and a small program that writes it to the board's eMMC on boot. Power the board with the card inserted, it flashes itself, you remove the card and reboot into the new firmware.
Preparing the card
You need an SD-boot image for your exact KTM board (not the same file as the
USB update.img unless your package says so) and a card-writing tool:
- balenaEtcher — cross-platform, hard to get wrong (recommended)
- Raspberry Pi Imager — cross-platform
- dd — Linux/macOS, powerful and unforgiving
With Etcher: select the SD-boot image, select the card, flash. That's the whole preparation.
# dd equivalent (Linux/macOS) — double-check the device node first!
# Writing to the wrong /dev/diskN will erase that disk.
sudo dd if=ktm-sd-boot.img of=/dev/sdX bs=4M status=progress conv=fsync
dd writes wherever you point it. Confirm the SD card's device node
(lsblk on Linux, diskutil list on macOS) before running — naming the wrong
disk erases it. Etcher exists precisely to avoid this.
Flashing the board
- Power the board off.
- Insert the prepared microSD.
- Power on. The board boots from the card and writes firmware to eMMC. A status LED pattern (per your board) indicates progress.
- Wait for the completion indication — do not remove the card or cut power mid-write.
- Power off, remove the card, power on. The board boots the new firmware from eMMC.
If you leave the card in, some boards will just re-flash on every boot — remove it once done.
When to use SD vs USB vs MaskRom
| Situation | Method |
|---|---|
| At the bench, PC available | USB flash |
| In the field, no PC | SD card (this page) |
| Board won't boot at all | MaskRom recovery |
SD flashing needs a board that still powers and boots from the card. If it's truly dead, only MaskRom will reach it.
Related
- Flash over USB — the bench method
- MaskRom recovery — for a board that won't boot
- Flashing overview — image types and the loader