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Raspberry Pi Universal Power Supply

Schmuckkästli (Swiss German): jewelry box

Hardware

Closed Schmuckkästli

Schmuckkästli with Raspberry Pi and Universal Power Supply

RaspiElf running

RaspiElf w/ TFT

Of course you do not need any monitor but it is very convenient to have one built in (e.g. HDMI Monitor 5" 800x480 from Adafruit). Especially if you want to use emulators like the YAZE-AG (Z80, CP/M Plus), the DOSbox, or a terminal emulator for the BASIC3. A USB keyboard can simply plugged in, I use Bluetooth keyboard because the Raspi has Bluetooth on board.

Buttons for Shutdown and Run

To keep prices down, the Raspberry Pi is missing something that most electronic devices come with: a switch to turn it on and off. That’s OK, you say, we’ll just pull the plug to turn it off. Unfortunately, this can lead to corruption problems with the SD card. All the instructions say you should run the shutdown command before pulling the plug, but this is not always possible, particularly when your Raspberry Pi is running headless without a connected keyboard and monitor, and possibly even without a network connection. So, what can a self-respecting DIYer do? The answer, of course, is ‘add your own switch’!

To switch off the Raspberry Pi from the console:

pi@cosmac:~ $ sudo poweroff

I would like to use only one button for turn off and on again the Raspi as described in How to add a power button to your Raspberry Pi but for this we need the GPIO3 and this pin is already used by the I2C communication. I instead chose GPIO21 (pin 40) for shutdown, this can be configured with overlays

Add following line to the file /boot/config.txt

dtoverlay=gpio-shutdown,gpio_pin=21

If the Raspberry Pi is in HALT mode then you can start it again with switch off (pull the plug) and switch on again or hit the RUN button.

P6 Pinout

Wiring the RUN and the SHUTDOWN switches

There is pullup resistor (10 k to 3.3V, pin 17) for SHUTDOWN switch

Front Plate Design

The front plate was created with Inkscape (for the design source file see cosmicos.svg). I used the fonts Retro Stereo Wide, RCA, and Univers Pro 65 Bold (non-free).