raspberrypi.org/magpi The Official Raspberry Pi Projects Book 37
PIMINIMINT Projects
>STEP-01
Mount the screen
The 2-inch screen is attached to the lid of the Altoids
tin using double-sided tape. The display board’s
white charge port needs to be near the hinge to avoid
stretching the wires.>STEP-02
Make a charger
Matt stripped the mini circuit board from a standard
phone charger and removed its USB port. This board
is then soldered to a slimline LiPo battery, and
connected via a switch to the Pi Zero.>STEP-03
Add connectivity
A headerless RedBear IoT pHAT is soldered
directly via a male 40-pin header to the Pi Zero to
provide WiFi and Bluetooth connectivity. If using
the Pi Zero W, this could be omitted.HOW TO TIN A PI
(shipping costs, and buying pre-
made parts gets very expensive),
so I had to find creative ways to
solve problems.”
This included a solution for
rechargeable battery power. “In
my first iteration, I had no way
to charge the battery,” explains
Matt. “An Adafruit PowerBoost
would have been ideal, as it puts
out enough amperage, but the cost
would have been tight for me. The
[Pimoroni] Zero LiPo is amazing,
and I am currently using it in an
ongoing project of mine; however,
it sits too high on the GPIO and
wouldn’t allow for the lid to close
with the screen inside.”
In the end, at the suggestion of
a co-worker, Matt opted to modify
a standard USB phone charger,
extracting its charging circuitry to
use with a slimline LiPo battery.
He also added an on/off switch. “I
had some issues regarding wiring
and power needs, but those were
related to where in the circuitry
I put my switch, and the kind
of switch I used,” he reveals.
“Changing to a better switch did
the trick.” Matt’s 2500 mAh LiPo
provides impressive battery life:
“I haven’t done a full 100%-0%
test and timed it, but I have had it
on for six-plus hours at a time.”
One drawback of using a built-in
battery was that there was no longer
room in the tin for the infrared
camera and full-size exterior USB
port featured in the original design.
“However, I do still have an interior
full-size USB [via an adapter] that is
available when opened.”
Matt is currently making a
second PiMiniMint for a friend,
featuring a few modifications: “His
is going to have two on-board WiFi
antennas and a dedicated SIM for
transmitting data over 3G/4G.”
As well as it being a cool pocket
PC, Matt thinks the PiMiniMint is
ideal for portable retro gaming.
“Additionally, I have used it as a
WiFi access point for saving files
to, a WiFi repeater by plugging a
second WiFi antenna into the USB
port, and I’m sure there are more
ideas out there!”Amazingly,
everything
fits into the
60×95 mm
Altoids tin;
there’s even
room for a
USB adapterRear solder pads on the Pi Zero are
used to connect the charger and
switch, and power wires for the screen