Despite the [silk on the dock board](https://wiki.makerdiary.com/nrf52840-m2-devkit/resources/nrf52840_m2_devkit_hw_diagram_v1_0.pdf), the SDA/SCL pins weren't defined. Though, they were already defined in `mpconfigboard.h`.
Same for RX/TX. It looks like it declared `TXD` and `RXD`, so I didn't want to remove those, but I think it makes sense to have the "standard" pin names, but I moved ithem to illustrate they were all referencing the same pins.
I mimicked the whitespace I saw in the metro_nrf52840_express port.
These changes remove the caveat from supervisor.runtime.serial_connected.
It appears that _tud_cdc_connected() only tracks explicit changes to the
"DTR" bit, which leads to disconnects not being registered.
Instead:
* when line state is changed explicitly, track the dtr value in
_serial_connected
* when the USB bus is suspended, set _serial_connected to False
Testing performed (using sam e54 xplained): Run a program to show
the state of `serial_connected` on the LED:
```
import digitalio
import supervisor
import board
led = digitalio.DigitalInOut(board.LED)
while True:
led.switch_to_output(not supervisor.runtime.serial_connected)
```
Try all the following:
* open, close serial terminal program
- LED status tracks whether terminal is open
* turn on/off data lines using the switchable charge-only cable
- LED turns off when switch is in "charger" position
- LED turns back on when switch is in Data position and terminal is
opened (but doesn't turn back on just because switch position is
changed)
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.
Mark Roberts
Dan Halbert
nitz
Jeff Epler
Ryan T. Hamilton
Scott Shawcroft
Ryan T. Hamilton
Brian Dean
Lucian Copeland
askpatricw
Jeff Epler
Rémi Sarrailh
Kamil Tomaszewski
Scott Shawcroft