The Official Raspberry Pi Projects Book - Projects_Book_v4

raspberrypi.org/magpi The Official Raspberry Pi Projects Book 67

>STEP-01

Managing the screens

The screens were used in portrait and

landscape modes. Based on their power

draw, the displays were distributed

between different power supplies

situated at the back of the hub plates.

>STEP-02

Connecting the Pi boards

The 23 Pi boards are installed across four

hub plates, with varying lengths of power

and HDMI cables running between the Pi

devices and the screens. The displays are

configured to use HDMI by default.

>STEP-03

Shining a light

Testing the screens is difficult because

the Pi boards are under the platform – one

person troubleshoots the Pi devices while

another checks the displays. The adverts

run via Adafruit’s Pi Video Looper.

LIGHTING UP A MINIATURE TIMES SQUARE

GULLIVER’S GATE Projects

Above Every cable has been carefully labelled to make

troubleshooting easier

mounting mechanism for the
frames based on the Banggood
screen dimensions. The frame
parts were cut in ⅛‑inch black
cast acrylic and they were sanded
and glued together with Acrifix
solvent cement.”

Construction and power
To fix the screen controllers to
the displays, the team marked the
mounting holes before drilling and
taping them. “We only used three
holes to mount the controller board
because its base is not ľat, and
tightening all four screws would

have tilted it to one side,” explains
Uttam. “The screens were attached
to the frames using clear VHB tape.”
With all of that in place, they
could attach the HDMI and power
cables to the screen controllers.
There wasn’t enough room for
standard cables, so they used
KGML ľat angle adapters, which

also provided a measure of safety.

“The board wouldn’t be damaged if

someone accidentally yanked the

cables,” Uttam tells us. The cables

were then secured with ties to keep

them contained.

Coding real adverts

With construction complete, they

could prepare the Pi Zeros. Uttam

burned the Raspbian OS on to a

microSD card using the Etcher app,

and installed Adafruit’s Raspberry

Pi Video Looper to display the ads.

“We used a library, so most of the

programming task was already

complete,” he continues. “But to

save some time in configuring all

of the Pis, I wrote scripts to set

static IPs and change host names.”

The Pi boards were connected

to a 24‑port Ethernet switch

and placed under the platform

on which the models sit. The

team could then begin to gather

Targeting visitors by running

real ads on the miniature

screens is a real stroke of genius

adverts, which have come from the

advertisers themselves, shining

brightly from the buildings they

adorn. “They really added depth

and dynamism to the otherwise

still buildings,” Uttam says of the

final result. ģTargeting visitors by

running real ads on the miniature

screens is a real stroke of genius.”