DFU flashing of apps sometimes aborts, and although rare this leads to
broken devices if no boot button or serial/jtag access exists, because
the bootloader will keep trying to start a half-flashed app that then
crashes at some point.
The easiest fix that works with existing bootloaders is to prepend a
small 512 byte stub that calculcates the crc and compares it with the
crc calculated at build time, and then either starts the actual app, or
sets the dfu flag and resets. This ensures we either have a working,
running app, or end up in the bootloader, ready to flash again.
For obvious reasons this only applies to dfu apps, and not to flash
targets like the actual bootloader itself.
Change-Id: Id6df0486c8b779889d21800dc2441b3aa9af8a5f
now both partitions (bootloader and application) use a commonly
defined memory location to shared the DFU state (which includes
the magic value to know which part to start), instead of using
a hard coded value.
the bootloader size has now also been restricted to 16 kB.
this limitation is enforced so to not be able to create larger
images, which could be corrupted when flashing the application.
bootloader and application flashing have been successfully tested
on qmod st12 and st34.
Change-Id: I204bed7e9391602672ed894decec1fc12e879275
This way we can easily check with 'diff' for differences in our code and
Atmel softpack. Also, this layout is more suitable for building various
different firmware images (e.g. factory-test, dfu-loader, main
application) for a variety of different boards (simtrace, owhw, qmod).
