Summary

A portable gaming system built using a Raspberry Pi and touchscreen display for the Raspberry Pi with Java book.

Kid tested and approved!

Instructions

The NightHacking RetroPi is designed to be straightforward to print (no generated supports required), straightforward to source (almost everything can be ordered from one supplier), and simple to assemble (snap together design).

I do go into more detail in my book, but want this to be a project anyone can print, so I have included all the source files, instructions, and detailed pictures here. If there is something I missed, please let me know and I will include it.

Here is what you need to finish the project:

Raspberry Pi 2 - https://www.adafruit.com/products/2358
SD Card with NOOBS - https://www.adafruit.com/products/1583
Adafruit DPI TFT Kippah for Raspberry Pi with Touch Support - https://www.adafruit.com/products/2453
40-pin FPC Extension Board + 200mm Cable - https://www.adafruit.com/products/2098
4.3" 40-pin TFT Display - 480x272 with Touchscreen - https://www.adafruit.com/products/1591
Mini Metal Speaker w/ Wires - 8 ohm 0.5W - https://www.adafruit.com/products/1890
Stereo 2.8W Class D Audio Amplifier - TS2012 - https://www.adafruit.com/products/1552
Thru-hole 5-way Navigation switch (Alps Model SKQUCAA010) - https://www.adafruit.com/products/504
Tactile Switch Buttons (12mm square, 6mm tall) x 10 pack - https://www.adafruit.com/products/1119
2x C&K D6F90 F1 LFS Switch – http://www.digikey.com/product-detail/en/D6F90%20F1%20LFS/401-1970-ND/1466327
1N4148 Diodes - https://www.adafruit.com/products/1641
PowerBoost 1000 Charger - Rechargeable 5V Lipo USB Boost @ 1A – https://www.adafruit.com/products/2465
Lithium Ion Battery Pack - 3.7V 4400mAh - https://www.adafruit.com/products/354
Breadboard-friendly SPDT Slide Switch - https://www.adafruit.com/products/805

For printing, I recommend 100 micron layer height (or finer) and thick walls (>= 1mm). Most parts can be printed with minimal infill, except the pins, which I recommend doing at 80% infill or greater. All the parts are oriented in the correct position in the exported STL files except for the pins (which should be printed with the nuts facing the build platform.

To assemble the RetroPi, here is the basic list of steps (with the corresponding pictures roughly in order):

Print all the parts for the project and check against the photo to make sure you have everything ready.
Solder a couple cables to the Raspberry Pi audio pads shown in the diagram (PP6 is ground and PP26 is the right channel). In general, a cable length of 10-12mm is about right for this and all the future connections.
Put the Raspberry Pi and Battery into the base (both of which have form fit holes)
Solder the Kippah 5V and Ground lines to the matching PowerBoost 1000C terminals. Also, connect the slide switch to the EN and GND pins on the PowerBoost (you only need to connect 2 of the 3 switch terminals).
Insert the PowerBoost and switch into the case per the photo.
Solder cables from the Kippah to all the buttons. Refer to the chart below for the wiring of buttons.
Attach the 200mm ribbon cable to the Kippah and gently tuck it under (no hard creases).
Attach the Kippah to the Raspberry Pi GPIO pins, being careful to route the cables and make sure the Kippah can lay perfectly flat.
Insert the D-Pad holder and add the 5-way switch to the form-fit slot. You can also pop the D-Pad printed part on at this time.
Insert the Button holder into the form-fit slot, and insert the 4 buttons into their respective holes. Pay attention to the direction of the A and B buttons, which only fit in one orientation with both flat edges facing each other.
Attach the screen base and carefully route the ribbon cable through the hinge by rolling it gently (again, be careful not to sharply bend or crease the ribbon cable).
Insert the left and right pins with the lock cutout facing up. They will fit best when the screen is open at a 120 degree angle. Then secure by adding the locks from the top (if they are tight, squeeze them into place with pliers).
Add the extension board and touch screen to the top. It is a tight fit, so be careful not to pinch the screen cable when inserting it.
Attach the console lid and screen lids. They are designed to slide and snap into place securely with no screws.

Here are the button assignments:

Kippah Lead	Connection 1	Connection 2	Connection 3
Ground 2	Navigation –	Select button –	Start button –
Ground 3	B button –	A button –
GPIO 27	B button +
GPIO 22	A button +
GPIO 23	Navigation left	Select diode 1
GPIO 24	Navigation down	Start diode 1
GPIO 25	Navigation right	Select diode 2
GPIO 26	Navigation up	Start diode 2

To run games, I have a modified version of the Java HalfNes emulator with GPIO controller support. You can find that codebase here:
https://github.com/RaspberryPiWithJava/halfnes

The Raspberry Pi comes with Java preinstalled, so you just need to load this project up in NetBeans and do a remote deployment. The main class is com.grapeshot.halfnes.JavaFXNES.

I also recommend the following "tweaks" to your /boot/config.txt:

Disable spi and i2c, we need these pins.

dtparam=spi=off  dtparam=i2c_arm=off  # enable the DPI display  enable_dpi_lcd=1  display_default_lcd=1  # For 4.3in displays  hdmi_ignore_edid=0xa5000080  hdmi_ignore_edid_audio=1  # Use these instead if you need to work on console:  # framebuffer_width=480  # framebuffer_height=272  # These work with JavaFX:  framebuffer_width=640  framebuffer_height=472  dpi_output_format=520197  # Flip the screen  display_rotate=2  # And adjust overscan as necessary  disable_overscan=0  overscan_top=150  overscan_left=160  overscan_right=0  overscan_bottom=-59  # Increase GPU memory:  gpu_mem=128

I also recommend a little overclocking. I did some burn-in testing, and these values seem to be pretty reliable on my Raspberry Pi 2 (your mileage may vary):

overclocking

arm_freq=1050  over_voltage=4  core_freq=525  gpu_freq=350  sdram_freq=480  over_voltage_sdram=2

Regardless of whether you overclock or not, you will need to change the governor on the Raspberry Pi 2 to be more aggressive so it will perform better. The default governor sees that only 1 CPU is busy and will throttle you to 600MHz, which is no good:
echo "performance" | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

Good luck with printing and assembling your RetroPi, and please let me know how your project goes by commenting on the project here and posting pictures of your creation!