Over 10 years ago the dfu-programmer project was forked into dfu-utils as the former didn’t actually work at all well with generic devices supporting vanilla 1.0 and 1.1 specification-compliant DFU. It was then adapted to also support the STM variant of DFU (standards FTW). One feature that dfu-programmer did have, which dfu-util never seemed to acquire was support for the AVR variant of DFU (very different from STM DFU, but doing basically the same things). This meant if you wanted to program AVR parts you had to use the long-obsolete tool rather than the slightly less-unmaintained newer tool.
Today I merged a PR in fwupd that adds support for flashing AVR32 devices from Atmel. These are the same chips found in some Arduino protoype boards, and are also the core of many thousands of professional devices like the Nitrokey device. You can already program this kind of hardware in Linux, using clunky commands like:
# dfu-programmer at32uc3a3256s erase # dfu-programmer at32uc3a3256s flash --suppress-bootloader-mem foo.ihx # dfu-programmer at32uc3a3256s launch
The crazy long chip identifier is specified manually for each command, as the bootloader VID/PID isn’t always unique for each chip type. For fwupd we need to be able to program hardware without any user input, and without any chance of the wrong chip identifier bricking the hardware. This is possible to do as the chip itself knows its own device ID, but for some reason Atmel wants to make it super difficult to autodetect the hardware by publishing a table of all the processor types they have produced. I’ll cover in a future blog post how we do this mapping in fwupd, but at least for hardware like the Nitrokey you can now use the little dfu-tool helper executable shipped in fwupd to do:
# dfu-tool write foo.ihx
Or, for normal people, you can soon just click the Update button in GNOME Software which uses the DFU plugin in fwupd to apply the update. It’s so easy, and safe.
If you manufacture an AVR32 device that uses the Atmel bootloader (not the Arduino one), and you’re interested in making fwupd work with your hardware it’s likely you just have to add one line to a data file. If your dfu-tool list already specifies a Chip ID along with can-download|can-upload then there’s no excuse at all as it should just work. There is a lot of hardware using the AT32UC3, so I’m hopeful spending the time on the AVR support means more vendors can join the LVFS project.
