The Wio Terminal includes a RealTek RTL8720D as a companion to the main chip to provide WiFi and Bluetooth capabilities via eRPC over a UART connection. The WIO Terminal schematic labels some pins as the RXD/TXD for the UART, and that was captured in the board definition for CircuitPython. However, these pins may be used for logging in another mode, but they are not the main pins used to communicate with the RTL chip. The correct configuration is RX on PC24/pad 2 and TX on PB24/pad 0 of SERCOM 0. The comments on the pin definitions now reflect this situation, for anyone trying to get the WiFi/BLE to work on the Wio Terminal.
Previous pins definition stated that the UART1 RTS and CTS were not connected. They are connected and can currently be used via A1 and PWM0 respectively. To make things a little clearer, enabling the RTS1/CTS1.
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.)
