While it’s true that your parts bin might have a few parts harvested from outdated devices of recent vintage, there’s not much to glean anymore aside from wall warts. But the 3×48-character LCD from [Kerry Wong]’s old Uniden cordless landline phone was tempting enough for him to attempt a teardown and reverse engineering, and the results were instructive.
No data sheet? No problem. [Kerry] couldn’t find anything out about the nicely backlit display, so onto the logic analyzer it went. With only eight leads from the main board to the display module, it wasn’t likely to be a parallel protocol, and the video below shows that to be the case. A little fiddling with the parameters showed the protocol was Serial Peripheral Interface, but as with other standards that aren’t exactly standardized, [Kerry] was left with enough ambiguity to make the analysis interesting. Despite a mysterious header of 39 characters, he was able in the end to drive the LCD with an Arduino, and given that these phones were usually sold as a bundle with a base and several handsets, he ought to have a nice collection of displays for the parts bin.
With how prevalent this protocol has gotten, [Kerry]’s post makes us want to get up to speed on the basics of SPI. And to buy a logic analyzer too.
