Based on Feather RP2040 SCORPIO, but new USB PID (from MBAdafruitBoards/Production) and pin name changes for GP16-23 (CKN/CKP etc., from board schematic).
This 2-in-1 PR started with the goal of support the Bangle.js 2
smartwatch with *no USB*.
* Adds "secure" DFU build support with a committed private key.
* Adds 3-bit color support with one dummy bit for the JDI memory display
* Allows nrf boards to have a board_background_task() run in RUN_BACKGROUND_TASK.
This is needed because the Bangle.js 2 uses the watchdog to reset.
* Renamed port_background_task() to port_background_tick() to indicate it
runs on tick, not RUN_BACKGROUND_TASK.
* Marks serial connected when the display terminal is inited. This means
that safe mode messages show up on the display.
ACep, 7-color epaper displays also pack 3 bits in 4. So, I added that
support as well.
* Adds 3-bit ACeP color support for 7-color e-paper displays. (Not
watch related but similar due to color depth.)
* Allows a refresh sequence instead of a single int command. The 7" ACeP
display requires a data byte for refresh.
* Adds optional delay after resetting the display. The ACeP displays
need this. (Probably to load LUTs from flash.)
* Adds a cleaning phase for ACeP displays before the real refresh.
For both:
* Add dither support to Palette.
* Palette no longer converts colors when set. Instead, it caches
converted colors at each index.
* ColorConverter now caches the last converted color. It should make
conversions faster for repeated colors (not dithering.)
Because this must be treated like an in-use pin for all other purposes,
unfortunately a special case must be added in shared-bindings.
Multiple AnalogIn objects for VOLTAGE_MONITOR can be created (because
in use tracking isn't working) but this causes no harm.
Testing performed: Read the monitor, then imported wifi. When the
pin state was insufficiently restored, the second step would fail
with debug messages about do_ioctl timeout.
```
import analogio, board
a = analogio.AnalogIn(board.VOLTAGE_MONITOR)
print(a.value)
import wifi
```
Closes: #7020
Closes: #7017
* Remove the 'GP23' alias for CYW1
* Remove the 'CYW0' alias for CYW0
* Switch VBUS_SENSE to CYW2, remove 'GP24' alias
Code that wants to use SMPS_MODE, VBUS_SENSE and LED while being
portable to the W and non-W variants should use those names, not alias
names.
* Remove A3 / VOLTAGE_MONITOR
Right now this cannot be used. The ability to check the voltage monitor
should be added back in some fashion in the future.
Note: at this time, the ssl module on pico_w never verifies the server
certificate. This means it does not actually provide a higher security
level than regular socket / http protocols.
Before this, CIRCUITPY would start at 1MB anyway. This appeared to work
only because I hadn't checked the actual size of the CIRCUITPY drive,
and because until now the flash hadn't actually crossed that 1MB
boundary into CIRCUITPY storage.
WARNING: on pico_w, upgrading/downgrading CircuitPython across this commit
boundary will erase the CIRCUITPY filesystem. After this commit,
switching between pico and pico_w firmware will erase the CIRCUITPY
filesystem
