I want to find a solution for the spark community and the RIOT community, which will work for both.
So replacing the bootloader will require spark community hardware owners to have a jtag to reflash back to spark software...and I think this is not that nice. Same for RIOT users. So the bootloader with the dfu utility is a nice thing I want to preserve if possible.
Right now the led is just directly red and flashing every 4-5 sec, probably this chunk of code (from bootloader):
// Set IWDG Timeout to 5 secs
IWDG_Reset_Enable(5 * TIMING_IWDG_RELOAD);
perhaps we find a solution where I can set some bits to indicate my needs to the bootloader and then issue a reset. The bootloader should read that need and signal back (by setting some bits) that it accepted the request.
PS I updated by code in the RIOT repo, so you have a look at it:)