This API change refactors the usbdev API to supply buffers via the
usbdev_ep_xmit function. This changes from the usbdev_ep_ready call to allow
separate buffers per call. An usbdev_ep_buf_t pseudotype is available and must
be used when defining buffers used for endpoints to adhere to the DMA alignment
restrictions often required with usb peripherals.
Main advantage is that the usbdev peripherals no longer have to allocate
oversized buffers for the endpoint data, potentially saving multiple KiB
of unused buffer space. These allocations are now the responsibility of
the individual USB interfaces in the firmware
By moving all the single byte struct elements to the end, we can reduce
padding inside `dose_t` and ensure that `recv_buf` is always aligned.
This saves some RAM:
master
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36384 136 12944 49464 c138 tests/driver_dose/bin/samr21-xpro/tests_driver_dose.e
this patch
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36484 136 12936 49556 c194 tests/driver_dose/bin/samr21-xpro/tests_driver_dose.elf
Some CAN transceivers have a standby pin that has to be pulled low
in order to use it.
If the interface is disabled we can set it to high again to save some
power.
BOARDs with RF switch might only support one of the TX modes, and
on init the BOARD needs to be configured accordingly and the correct
mode selected on TX.
The bogus packed attribute added to lis3dh_data_t resulted in the
structure being aligned two 1 byte. It was later casted to an
uint16_t pointer (which is aligned two 2 bytes). By dropping the
packed attribute the alignment mismatch is fixed.
A fixed timeout is either too long for high symbol rates or too short
for low symbol rates.
To fix this, calculate the timeout based on the symbol rate.
For this, the old 5ms timeout is equivalent to 58 bytes being transmitted
at 115200 baud (8 data bit + start & stop bit).
I rounded this to 50 bytes which should yield 4340 µs.
There is no way to properly handle incorrect SPI parameters at run time, so
just having an assertion blow up is the better choice here.
As most instances of `spi_acquire()` don't check the return value anyway, this
will improve debugging experience quite a bit. Some implementation of
spi_acquire() don't even check parameters anyway.
