We had originally paid a friend from the QC Co-Lab (Davenport, IA) to write a library for the PCA85162 LCD Driver while we were working on the TEC-Tach. The library worked well but when we finally got to using the hardware we had to make change which took up too much board space and we also changed the lcd. We had to save space & rewrite part of the library so we gave up on the PCA and opted to using qfn shift registers.
The only thing is you need to have numpy to use the script, I’m kinda new to python so using numpy was about the only way I figured out how do things like I wanted to.
The library which can be found here works by using two separate functions one to set the display buffer and then another to actually shift out the the buffer to the registers and then inverts the display buffer so it will generate a AC waveform when it is called again. As long as you run the display function more than you update the display buffer it will drive the display, you may want to consider running it on an interrupt or just put it in some looping code, it doesn’t hurt to be updated frequently and can stay ‘lit’ without a polarity change for a some time. It made routing our board a bit easier and the qfns take up less space than the original 56-TSSOP PCA driver.
as you can see our board is a bit busy since we aren’t putting anything behind the capacitive touch buttons.
Hope this is helpful to someone out there!