Monday, May 28, 2018

Building a display

Here I'm going to show you the steps to building one of our latest displays. This is just commodity Raspberry Pi hardware in a 3D printed enclosure, but it may be interesting to readers to see what goes into the device. We start with all the components laid out:


There's a 4.3" HDMI LCD display; a Raspberry Pi 3; an XBee breakout board; an actual XBee with a u.FL to RP-SMA connector and a 2.4 GHz antenna; a pushbutton encoder; a 3D printed enclosure with standoffs and screws; and a RAM mount base with screws. We have already wired the XBee breakout board and the encoder to the solder pads on the LCD display, which are wired into the Raspberry Pi.

Next we assemble the XBee into its socket. We mate the Raspberry Pi to the LCD circuit, and attach the (clumsy, I know, I know...) HDMI connector:


We then insert this into the back of our case:


And then we add our screws and standoffs to secure the LCD into the case (this also holds in the Raspberry Pi):


We then insert the encoder into its matched slot in the case:


And tighten the panel nut on the opposite side:


We then attach the u.FL to RP-SMA wire in the case panel mount slot, and attach the u.FL connector to the XBee:


Meanwhile, we screw the RAM ball to the case back. Note that it has a grid of #8 holes allowing the base to be positioned as you need it:


We then put some 3M VHB tape on the back of the XBee breakout and mount it to the case back:


Finally, we screw on the case back from behind:


We then attach the antenna and press the knob onto the encoder shaft:


This also works with a stubby antenna, depending on how far your probe is from your display and what's between them. Here is Linux booting up:



And here is an Airball display showing strong wireless signal (the battery status monitor is not yet working):



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