Add SH1106 display support

[Anomalocaridid]

Currently, the OLED extension only supports displays that use the SSD1306 chipset. This PR adds support for displays with the SH1106 chipset.

Essentially, I accomplished this by making both displays display types through subclasses of a new class called OledDisplayType. These would be created and passed to the constructor for Oled rather than passing display-specific parameters such as I2C and SPI pins. Display-specific logic is handled by methods in each display's class, which are called by the Oled class's methods with the same names.

Using an SH1106 display requires the adafruit_displayio_sh1106 library, but I made it so that you only need the library for the display(s) you are using by importing them within the displays' classes' methods rather than globally.

I did some minor testing and it looks like it works fine. However, I noticed that one short line of pixels one the edge of the screen, presumably from the CircuitPython boot screen, lingers and I am not entirely sure what the cause is. Also I do not own a keyboard with a SSD1306 display, so I need someone else who has one to check that I did not break anything.

Unfortunately, this PR introduces some breaking changes for users and might interfere with #830. However, I am more than happy to wait until #830 gets merged first and then rebase my PR branch and update the documentation myself if necessary.

Instead of initializing the OLED extension with something like:

import board
import busio
from kmk.extensions.oled import Oled

i2c_bus = busio.I2C(board.SCL, board.SDA)
Oled(i2c=i2c_bus)

You would use something like:

import board
import busio
from kmk.extensions.oled import Oled, SSD1306

i2c_bus = busio.I2C(board.SCL, board.SDA)
display_type = SSD1306(i2c=i2c_bus)

oled = Oled(display_type=display)

For an SH1106 display, it would look like:

import board
import busio
from kmk.extensions.oled import Oled, SH1106

spi_bus = busio.SPI(board.SCK, board.MOSI)
display_type = SH1106(spi=spi_bus, command=board.DC, chip_select=board.CS, reset=board.RESET)

oled = Oled(display_type=display)

Note that for the SH1106 display, it requires pins other than the ones used to create spi_bus. Also, I made sure to include the option to just specify the pins and have the classes' __init__() methods create the I2C/SPI bus for you like it was before.

[Anomalocaridid]

Apparently some displays' drivers are built into CircuitPython and do not need any manual initialization. So I added support for those. Interestingly, this includes my own macropad and using this instead of the SH1106 library solves the problem I mentioned earlier:

However, I noticed that one short line of pixels one the edge of the screen, presumably from the CircuitPython boot screen, lingers and I am not entirely sure what the cause is.

You would initialize one of these displays like this:

import board
from kmk.extensions.oled import Oled, BuiltInDisplay

display_type = BuiltInDisplay(display=board.DISPLAY)

oled = Oled(display_type=display)

Of couse, using displayio.release_keymaps() would interfere with already-initialized displays, so I moved that to the other displays' __init__() methods

[xs5871]

I generally approve, give some time to go into the review.

[Anomalocaridid]

Sorry for adding another change after you already started reviewing my pull request, but I discovered that my last change breaks sleep and wake functionality for built-in displays, so I went ahead and fixed it.

BuiltInDisplay's constructor now takes numbers corresponding to display-specific sleep and wake commands. Sleeping and waking is now handled by the respective methods in the different display types' classes rather than directly by the display's methods.

Using a BuiltInDisplay now looks like this:

import board
from kmk.extensions.oled import Oled, BuiltInDisplay

# Command arguments shown are for example purposes. I assume different displays have different commands for this.
display_type = BuiltInDisplay(display=board.DISPLAY, sleep_command=0xAE, wake_command=0xAF)

oled = Oled(display_type=display)

[Anomalocaridid]

How's this?

• I changed display_type to display, replacing the existing display attribute.
• I changed OledDisplayType to DisplayBackend. I ended up keeping it around because it gained a significant amount of shared code.
• I changed "OLED_Display.md" to "Display.md" and updated it.
• I changed some miscellaneous occurrences of "oled" to "display".
• I also took the liberty of replacing the use of Display.show() with Display.root_group because it is apparently deprecated.

[Anomalocaridid]

Thank you!

[regicidalplutophage]

Good work @Anomalocaridid @xs5871 !