If a COLDCARD is powered down during the firmware update process, the intended (new) firmware image has been lost because it it held in PSRAM (volatile memory) during the flash writing process. The COLDCARD bootloader is smart enough to detect this specific case, and read an SD card to recover and avoid becoming a brick.
The bootloader will only install an image of exactly the same version as was being installed when interrupted. This is done by verifying the checksum vs. the value that had been set in SE1 by the PIN holder. This prevents side-loading or up/downgrade attacks.
This projects holds data and code to build a special SD card disk image with all possible releases. The goal is a single disk image that can be used restore a COLDCARD of any version included.
We may not update this every single release, but if you have a need, please contact support and we are happy to update it!
Take the most recent *.img.xz file from output directory
and image it onto an SD Card, uncompressed. We recommend Balena
Etcher to do this in one step on MacOS. Turn on the COLDCARD with
the card inserted, and the rest is automatic (although not fast).
Note you cannot see the files on this card, and please do not make any changes to the card after imaging it. It's not really a FAT-formated filesystem, and the firmware images need to be located at specific blocks.
Add DFU files you want to include in releases. You can include as many or as few as you wish, since the bootloader will try each one in sequence until it finds a working checksum.
You will need mtools installed and basic Unix utilities in your path.
Type make to run the Makefile and construct a new file in output.
- COLDCARD Mk4
- COLDCARD Q