Monday, February 29, 2016

Two Raspberry Pi 3 Hardware Hacks

No sooner has the Raspberry Pi 3 been released, let's see about making it better. I'll point out a couple of items not widely discussed that may lead you to your hacking.

Unpopulated uFL Connector

The Raspberry Pi 3 has built-in Wi-Fi and Bluetooth.  The standard antenna is a board mounted chip connector circled in red on the front side of the board below:

Front View
And look on the back below.  The red circle shows the blank PCB area opposite the front chip antenna (you don't want parts here to avoid interference).  All good.

Rear View
Now look at the 2 copper pads marked J13 circled in orange. The area between the copper squares is about the same area that would be occupied by a uFL antenna connection.  What type of connection is that? uFL connectors are very small surface-mount parts used when an external RF antenna is desired. They used on GPS and Wi-Fi boards.
Close-up of pad J13 and a uFL solder connector (not to the same scale)
The solder mount uFL connector shown at right above are available for around a dollar at many electronics outlets.  Most of those same outlets have inexpensive external antennas to connect to the uFL connector. Be careful, these connectors are somewhat fragile (they bend or crush if the mating plug is pushed on wrong). You can also find uFL to SMA and uFL to RP-SMA adapter cables to use larger antennas or use panel mount antennas.

Touch Screen Connector

The rear picture above has a spot shown in yellow.  This is opposite the HDMI connector on the front.  It is not shown with any part soldered there above and on the Raspberry Pi 2.  But the FCC testing picture of the rear shows a ribbon cable connector on the board.
Leaked Raspberry Pi 3 FCC Testing Board with Populated Connector
This connector is similar to the one used on the interface board for the Raspberry Pi official 7 inch touchscreen display.  I suspect this is for a touch interface but it is not documented or labelled.  Other iterations of the Pi have had test points here.  Why does this get so much attention but no parts or documentation?  It's up to us to us. Do note that hardware modifications may void your warranty or change the wireless certification. . .

There is so much potential to this third generation board.  Let me know if you have found things to do with it.