set_border AC073TC1A appears non-functional

[starvedforknowledge]

I have an older inky impression 7.3" that I have recently resurrected for a new project.

I wanted to test the functionality and noticed that the set_border method doesn't appear to be changing colours as expected.

I've dug into the module (namely inky/inky_ac073tc1a.py) and it looks like the border_colour attribute is set but never used during the _update procedure.

I took a look around for a data sheet but didn't manage to find anything that looked relevant, but I am also no expert on these devices.

I was hoping to find out the following:

• does this model (AC073TC1A) have a border color functionality?
• if so, is there a data sheet on hand I could reference? (I'd be happy to try and implement the update and submit a PR if this is available)

Thanks!

[starvedforknowledge]

Update here for those who may run into the same problem:

• A similar issue was reported some time ago for the UC8159 driver: inky.set_border() from examples/7color/cycle.py is not implemented for inky_uc8159 #92
• Tracing the work that solved that issue shows a small fix in the setup method: 0676a73#diff-0488bd0af17895d2555523d984032d519099d03fd2a2c3731b199eba84843da2L283
• We can copy this almost verbatim into inky/inky_ac073tc1a.py at the following location:

  inky/inky/inky_ac073tc1a.py

  Line 261 in 5bb44a2

  self._send_command(AC073TC1_CDI, [0x3F])

The result is a replacement like this:

-self._send_command(AC073TC1_CDI, [0x3F])

+cdi = (self.border_colour << 5) | 0x17
+self._send_command(AC073TC1_CDI, [cdi])

I've confirmed this works on my panel but I don't understand why or what it is doing! I'll leave it to the maintainers to decide if this fix makes sense and whether to integrate.