PiUniDeck: Portable Multi Operating System Long-working Pi Deck

by VadymOstanin in Circuits > Raspberry Pi

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PiUniDeck: Portable Multi Operating System Long-working Pi Deck

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I designed this handheld deck being inspired by other HandHeld projects. I also wrote the step-by-step guide to make it straightforward for anyone to build. This project is completely free to build under the Creative Commons BY-NC-SA 4.0 license. During working on articles I found my version visually is similar to "YARH.IO MKI" https://yarh.io/yarh-io-mki.html but it was designed from scratch.

Downloads

Case Assembling

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I started by assembling of acrylic case with fan to Pi3B+ using screws 2.5mm x 25mm. Fan' existence is important as it will cool down Pi.

Power Wiring Pi3B+

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Then I soldered wires to probe points at back of board Pi3B+ named PP2 for further ( not now ) connection to 5V positive power supply and (PP5 or PP6) for 5V negative power supply, about 10 cm long.

Prepare SD Extender

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Then I prepared SD card extender 25 cm long. Initially SD card extender does not work, and I found that it is common problem and is solved by desoldering one resistor of 330 Om.

https://forums.raspberrypi.com/viewtopic.php?t=269457

https://forum.arduino.cc/t/micro-sd-extender-cable-not-working/958431/7

Then I connected SD extender to Pi and folded cable so that only SD case was out of Pi.

Mount Screen

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Then I screwed the screen to the Pi case using same 2.5mm x 25mm screws and connected the DSI cable to the display.

Prepare USB ExtenderŃ–

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I prepared three USB extenders: firstly I soldered the male and female USB connectors using 0.5mm wires, and then filled them with epoxy resin. Length is 4 cm.

Power of Pi/Keyboard/Indicator

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To power Pi/Keyboard/Li-ionindicator I used IRFZ44N MosFET, although Gate threshold voltage is 2V-4V at the datasheet, practically at 1.5V the Drain current is 10-20mA, and all electronics work fine even at 3.0 volts at Gate, but practically Battery voltage won't decrease lower than 3.3V.

At the diagram, I represented how I connected each electronic component.

I inserted a wireless Keyboard USB stick to one of four USB ports to establish communication between Pi and Keyboard.

For keyboard, I disconnected an internal battery, and left MosFET inside of Keyboard.

All MosFETs and soldered joints were covered by hot glue to prevent short-circuit.


For other Raspberry Pi versions 4/5, the Gate voltage should be supplied from some Buck converter at least 5v, because Pi 4/5 current consumption is bigger.

Cutting Bottom of Box Holes

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Then I made holes in the bottom part of the Box for the PowerBank module, USB extenders and SD card extender.

Assembling to Bottom Box Part

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Next step is putting the powerbank module and USB extenders in appropriate holes and connecting battery ( 10Ah for now) to powerbank module.

Fixating Keyboard and Pi

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Keyboard was fixated above Battery by placing on polystyrene foam and pins for screws, and fixated by hot glue.

Pi fixated by polystyrene foam

Cutting Top of Box Holes

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I cutted out of top box part:

- height from ~30 mm to 14-15 mm.

- all plastic parts that interfere Keyboard and Touchscreen interaction.

- pins for screws

Fixating Li-ionIndicator and Button

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I fixated Li-ion indicator by polystyrene foam and hot glue. Button is just inserted, fixated by it's own friction.

Assembling Box Parts

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I fixated the bottom and top box parts with reinforced adhesive tape.

Add SD Adapters

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I added two SD adapters for now, but the amount of SDs is limited only by Box's free space.

I fixated by reinforced adhesive tape.

Add Second Battery

I added several 10Ah/(2x2Ah) Lipo batteries under the Keyboard to increase Battery capacity up to 24 Ah.


My Pi 3B+ with Screen without Keyboard with OSs (Batocera, Raspberry Pi OS, Armbian) consumes roughly ~1.25A ~5V.

(24*3.7)/(1.25*5)=14 hour optimistic maximum, but if I took 2/3 of 14 hours =~ 9.5 hours Pi should work fine.

Keyboard enters the low power mode after 1-2 minutes, so do not count it's consuming.

PiUniDeck can be used as PowerBank due to PowerBank module usage.

Done!

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Now you can enjoy your new deck for work and fun.