Honestly? Chips are full of undocumented commands. It's really, really annoying. I've been working on getting small TFTs working, for example. Many of them use

Honestly? Chips are full of undocumented commands. It's really, really annoying. I've been working on getting small TFTs working, for example. Many of them use a common driver chip that supports your basic 8080 parallel interface. The driver manufacturer provides a datasheet documenting the various commands which it will accept. So of course, to start the chip up, you need to send it a series of magic commands and data values which are not documented in the datasheet. Adafruit was kind enough to explain the reasoning behind these values to someone who was presumably walking through the same steps as me to bring one of these screens up: https://forums.adafruit.com/viewtopic.php?f=47&t=63229 https://forums.adafruit.com/viewtopic.php?f=47&t=63229 I guess that maybe it prevents people from buying secondhand stock and getting it working from just the datasheet, without involving the original manufacturer? Anyways, caveat emptor. Even when there's only one seller to emptor from.