Lightly tested:
* no matches (catch-all)
* standard address single address matches (even and odd positions)
* standard address mask matches
* only tested that extended doesn't match non-extended
Tested & working:
* Send standard packets
* Receive standard packets (1 FIFO, no filter)
Interoperation between SAM E54 Xplained running this tree and
MicroPython running on STM32F405 Feather with an external
transceiver was also tested.
Many other aspects of a full implementation are not yet present,
such as error detection and recovery.
I recently misdiagnosed a "maybe-uninitialized" diagnostic as a bug in
asf4. However, the problem was in our SPI code.
A special case for samr21 MCUs was being applied to same54p20a and possibly
other D5x/E5x MCUs, since the check was simply for pin PC19 existing at all.
Change the check to use the macro PIN_PC19F_SERCOM4_PAD0 which is only
defined if special function F of pin PC19 is SERCOM4 PAD0.
Reorganize the code a little bit so that brace-matching in editors is
not confused by the conditionalized code, including an unrelated change
for APA102_SCK's condition.
Revert the change to the Makefile that incorrectly attempted to silence
the diagnostic.
.. there is an instance of it that looks like a "true positive", but it only
affects sdhc transfers that are not a multiple of 4 bytes, which I don't think
happens. (sd card blocks are always 512 bytes) I can fix this in our
asf4 repo but that would mean this should be deferred until after #3384 is
merged, since that also touches asf4 very invasively by adding a whole new
chip family.
If any diagnostics occur, we will want to either add `/* FALLTHROUGH */`
or `break;` as appropriate. I only tested a few builds (trinket m0
and metro m4 express)
Limor confirmed that the all shipping revisions starting with Rev D had QSPI flash chips installed.
Note that when neither EXTERNAL_FLASH_QSPI_SINGLE nor EXTERNAL_FLASH_QSPI_DUAL is specified quad mode is assumed, so this is addressed by removing the setting altogether.
