Been meaning to innovate this one for a while, but nobody had datasheet for the board to board connector that the 7.9" iPad mini 2 (2048x1536 retina) LCD used. Finally caved in and bought some from a random Chinashop (about $80 shipped for MOQ, ugh), scanned them, used amazing augenmass tool to calculate dimensions, and made a PCB hoping it would work.
Keen arduino developers will notice there's some extra circuitry which will be a subject of a separate post, however it does appear to function after some quick testing.
Assembly was pretty uneventful, and the annoying fine-pitch FPC connector actually matched my "guessed" footprint and soldered correctly. The board powered up on the first try, and nothing seems broken so far. Current draw at full brightness is a nice 510mA.
I used MicroUSB for power this time (again with external 5V on pads if needed), and the same huge full-size DP connector. All my attempts to source a decent MiniDP connector that wasn't a complete pain in the ass to solder didn't end well. I got some samples that were half-smt half-through-hole but there was about 3 or 4 different vendors for those and each one had slightly different layout for mounting pegs, and I didn't have time to sample them all to find out which one was the most commonly used. Molex also has a all-through-hole one, but it didn't seem to be very available either. So, big size DP for this one.
I quickly ported the firmware from the other displayport adapter to run on new board, so it basically has the same functionality. On the new PCB I added a pad for the button signal so that the power/control button can be placed outside a case or similar, if required.
Here's some pics of first finished board (I only made one).
Full-resolution pics are in picasa album here.
|Close-up pic. See if you can spot the innovation.|
|Backlight + power ON. The board fits behind the LCD, and with default landscape orientation, USB + DP connector are on the top.|
|Backlight off, "standby"|
|Drawing a cool 510mA at 5V|
|This looks pretty small compared to my two Dell UP2414Q|