Discussion
in order to fulfill its purpose Papyrix needs a driver for the Xteink X3/X4 eink display, so I'm at least starting to skim over that today.
There's several magic numbers including several lookuptable. There's a setter (with a support method) for overriding the screen dimensions & an underlying driver to reflect the X3 hardware rather than X4. Several methods defer to that underlying driver, & one of which checks which driver's being used.
An initializer sets properties & logs stuff.
1/?
A begin method logs some debug output, unsets a flag, resets & zeroes out some framebuffers, clears several other properties, inits an SPI channel, inits a couple other pins, handles the UC8279 driver specially, via another method pulses a reset pin, sends various reset commands via yet another method with support routines, & logs success.
There's a method to wait for a busy pin to go low. There's a method to send SPI command with chip-select & data pins low. Or with the data-pin high.
2/?
There's also methods which sets those pins letting the caller send the SPI commands itself.
For some reason there's a 2nd method for waiting until the appropriate busy pin's low.
There's a method for sending commands to set which region of the eink display's RAM is displayed. A method to memset the framebuffer. A method to copy an image into the framebuffer, & variant which adds transparency. One to send the command to write to the display's RAM, with variants.
3/?
There's a method which sends various output to (apparently) resynchronize the display. One that copies data into the framebuffer. One to swap framebuffers (unless a compiletime flag's set). It uses a method of the underlying driver or a custom Look-Up Table to perform a grayscale-revert.
It can use of 3 approaches to copy grayscale-LSB (Least-Significant Bit) buffers to the display, or another method handles MSB (Most-Significant Bit). With yet another method merging these methods together.
4/
There's methods to ask the underlying driver or send SPI commands to apparently:
* cleanup grayscale buffers.
* display the framebuffer.
* update only within a rectangular region of the screen.
* display the shades of gray.
* refresh the display.
* set a custom Look-Up Table.
* send the display into deep sleep.
And there's a method to serialize the framebuffer into a file.
5/5 For today! I'll probably finish this support library tomorrow.
I'll probably have to swap it out for my screen.
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