I'm currently "evaluating" (i.e. googling) bootloader options for the Atmega32u4 and maybe the At90usb1286.
I found 9 so far:
- AVRUSBBoot, 2KB, proprietary open source license (by Objective Development), C++ source for loader, requires driver on Windows?, V-USB based (low speed 1.5MHz)
- LUFA HID, 4KB, Open Source, works with the modified Teensy CLI which is also open source.
- LUFA DFU, 4KB, works with Atmel FLIP or dfu-programmer, which is open source
- LUFA CDC, size?, works with AVRDUDE
- USBaspLoader, 2KB, works with AVRDUDE, GNU GPL, V-USB based (low speed 1.5MHz)
- BootloadHID, 2KB, comes with command line tool, separate GUI available, V-USB based (low speed 1.5MHz)
- Atmel DFU loader, 4k, requires FLIP which is not available for OSX (or dfu-programmer?), closed source
- Arduino Leonardo bootloader, 4k, open source, requires Arduino envrionment?
- Teensy Halfkay, 0.5kB, only available with Teensy, Teensy Loader or CLI, closed source (not the CLI)
So far the LUFA HID seems to be the most attractive. With BootloadHID on second (in case V-USB is not required) and AVRUSBBoot being third.
Am I overlooking something? Experiences?
I'm also not sure if the Atmel DFU loader comes preinstalled on new ATmegas. But the programming options seem to lack simplicity.