the higher baud rate allows for more debugging (without dropping
data) and is well supported by USB for UART adapters (this
standard baud rate is 8 x 115200).
the closest matching integer value is calculated for UART CR.
no floating point calculation can be used since this would
increase the size of the resulting binary by ~ 2kB (for the
softfp). this is not possible for the DFU since it already is
close to the maximum size of 16 kB.
Change-Id: I82b74f697342d580ccb79ada4715f35f4e8cca86
UART baud rate is main clock (MCK) divided by CR*16.
The MCK values are chosen >= 48 MHz and <= 64 MHz to have a near
integer value CR for a baud rate of 921600 bps.
The end MCK frequency between simtrace and qmod differ slightly
but are close to 58 MHz.
Change-Id: Iaa4a97fc68494c93b9d128503515d88049de506c
USB reset can be signaled by pulling low USB D+ for at least 10 ms,
according to the USB specification. This force a re-enumeration.
This time is increased to 20 ms to work with more USB HUBs.
Some SAM3S based board have external D+ pull-up mechanism (such as
SIMtrace) which needs to be used to pull D+ low.
This is a legacy mechanism from SAM7S history.
This mechanism is not required anymore on the SAM3S, and the qmod
does not use it. When the USB HAL is suspended, the transceiver is
disabled, causing D+ and D- to be pulled low. Then the HAL is activated
again. This is particularly required when DFU is started (and
enumerated), and after flashing the SAM3S switched to the main
application (without reset), so it can properly re-enumerate.
This board difference is now defined on the board header.
Change-Id: I9b58d8101c2fcf5595026b675728826af26127a3
Each board can define its own conditions on which the controller should
boot into DFU mode rather than normal application mode. Let's move the
"UART loopback jumper" to QMOD specific part. For SIMtrace we have an
actual button and can use that in a future patch.
This was introduced for interoperability with operating systems that
might prefer such setup (I heard that Windows prefers this about a
decade ago, but I don't have any personal experience with it).
However, using different VID/PID between DFU and RT breaks usability of
dfu-util, and I really think this matters much more to our users and
developers.
* we now actually route the EP0 control requests in DFU mode to the
correct handler (weak linker symbols are tricky)
* we now actually call code to read/write data from/to RAM/FLASH
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).
