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.)
.. a fast helper for animations. It is similar to and inspired by the
PixelMap helper in Adafruit LED Animation library, but with an extremely
fast 'paste' method for setting a series of pixels. This is a common
operation for many animations, and can give a substantial speed improvement.
It's named `adafruit_pixelmap` so that we can package a compatible version
in pure Python for systems that can't fit it in C in flash, or for
Blinka.
This is a proof of concept and can make a very fast comet animation:
```python
import time
import adafruit_pixelbuf
import adafruti_pixelmap
import board
import neopixel
from supervisor import ticks_ms
from adafruit_led_animation.animation.solid import Solid
from adafruit_led_animation import color
pixel_pin = board.GP0
pixel_num = 96
pixels = neopixel.NeoPixel(pixel_pin, pixel_num, brightness=1, auto_write=False, pixel_order="RGB")
evens = adafruit_pixelmap.PixelMap(pixels, tuple(range(0, pixel_num, 2)))
odd_indices = tuple((i, i+2) for i in range(1, pixel_num, 4))
print(odd_indices)
odds = adafruit_pixelbuf.PixelMap(pixels, odd_indices)
assert len(odds) == len(odd_indices)
comet_length = 16
comet1 = [color.calculate_intensity(color.GREEN, ((1+i) / comet_length) ** 2.4)
for i in range(comet_length)]
comet2 = [color.calculate_intensity(color.PURPLE, ((1+i) / comet_length) ** 2.4)
for i in range(comet_length)]
pos1 = 0
pos2 = 96//4
while True:
evens.paste(comet1, pos1, wrap=True, reverse=False, others=0)
pos1 = (pos1 + 1) % len(evens)
odds.paste(comet2, pos2, wrap=True, reverse=True, others=0)
pos2 = (pos2 - 1) % len(odds)
pixels.show()
m = ticks_ms()
if m % 2000 > 1000:
time.sleep(.02)
```
