Development repository of a handheld console for PICO-8 games that runs with a Raspberry Pi Zero.
This project is ongoing. An MVP is not available yet.
The picoboy will be available here: https://github.com/isacben/picoboy
- Define requirements (actually, limitations) for an MVP on a PCB
- Prototype of a game pad using a breadboard.
- Look for a power supply board and a battery.
- Look for an audio amplifier board and a speaker.
- Learn about displays.
-
Look for a perf board and buttons for the game pad. -
Design an enclosure?
- Test Raspberry Pi GPIOs voltage: should be 3.3V.
- Test PICO-8 on the Raspberry Pi.
-
Test PICO-8 on the RG35XX. - Prototype a display using an Adafruit TFT display.
- Learn about Eagle CAD
- Order a Game Boy Color shell.
- Look for a display that fits on a Game Boy Color shell.
- Design a PCB based on the Gaboze Pocail (see Similar projects)
- List MVP components
- Order display
- Order RPi Zero W and charger
- Order audio amp plus components (
speaker, headphones jack, volume wheel, capacitors & resistors) - Order PCB
- PCB that fits in a Gam Boy Color or Pocket shell
- Holes for RPi headers
- Power the device by powering directly the RPi (no battery)
- Connect a display to the PCB
- Display connector on the PCB?
- Buttons directly on the PCB (Retrogram from Adafruit will be needed)
- Amplifier on the PCB with through holes components or the Adafruit PAM8302
- Volume wheel and headphone jack
- 8 ohms speaker
- Power switch?
- USB (mini?) connector to plug the chord on the PCB and a connection to the RPi
- Game Boy Color shell with no modifications (hopefully)
- Install Raspberry PI OS
- Configure Raspberry PI to boot to console
- Install PICO-O8
- Solder the 50 pin connector to the LCD screen adaptor
- Solder headers for the LCD screen adaptor
- Test LCD screen with the Raspberry Pi 3 A+
- Test buttons
| Part | Product | Estimated Price |
|---|---|---|
| Raspberry Pi Zero 2 W | Adafruit | $15.00 |
| Raspberry Pi charger | Adafruit | $8.25 |
| Display | Adafruit | $14.95 |
| RPi headers | ? | $0.00 |
| Audio amplifier | Adafruit PAM8302 | $3.95 |
| Volume wheel | ? | $0.00 |
| Headphone jack | ? | $0.00 |
| 100uf capacitor (headphones) | ? | $0.00 |
| 100K ohms resistor (headphones) | ? | $0.00 |
| 8 ohms speaker | Handheld Legend | $3.99 |
| Game Boy Pocket Shell | Handheld Legend | $7.99 |
| Game Boy Pocket Silicone Membranes | Handheld Legend | $2.79 |
| Game Boy Color Shell | Amazon | $20.66 |
The amplifier can consist of a circuit similar to the one present on the Gaboze-Pocaio, using the LM4875M/NOPB. The circuit is basically the example documented in the data sheet.
The LM4875M/NOPB provides a way to disconnect the speaker when headphones are detected.
The circuit itself includes the following components:
| Component | Description | Reference part | Value |
|---|---|---|---|
| R17 | Potentiometer | ? | |
| R18 | Resistor | ERJ-PA3J151V | 150 Ohms |
| R19 | Resistor | ERJ-PA3J104V | 100 kOhms |
| C7 | Capacitor | CL10C221JB8NNNC | 220pF |
| C8 | Capacitor | CL10A105KP8NNC | 1uF |
| C9 | Capacitor | CL10A105KP8NNC | 1uF |
| C10 | Capacitor | 6TPH100MAEA | 100uF |
| J1 | Audio Jack | SJ1-3525NG-GR | - |
| J2 | Speaker | SKU PRT-09914 - example | 8 Ohms |
The following diagram shows how to connect the SJ1-3525NG-GR audio jack to the LM4875M. Some of my notes are in Spanish.
The diagram shows the audio jack pins (1 to 5) and what should be connected to each pin:
- Pins
4and5are connected to pin3 of the amplifier(LM4875M), which is the HP-Sense headphone control pin. This control pin deactivates the speaker when the headphones are connected (the switches are open). - And pins
2and3are connected topin 5 of the amplifier(the output), which is the audio source (audio signal).
| PIN | SJ1-3525NG | LM4875M |
|---|---|---|
| 1 | sleeve | GND |
| 2 | tip | 5 |
| 3 | ring | 5 |
| 4 | tip switch | 3 |
| 5 | ring switch | 3 |
TODO
TODO
Possible displays, based on the Game Boy Pocket shell window size:
- Maybe the best option, although I would need to modify the GBP shell and the display would not cover the entire window (in the Game Boy Color, the display does cover the shell's window): https://www.adafruit.com/product/1774
- Maybe this one for the Game Boy Color shell: https://www.adafruit.com/product/4278
- https://www.digikey.com/en/products/detail/displaytech/DT024CTFT/6650296
- https://www.digikey.com/en/products/detail/newhaven-display-intl/NHD-2-4-240320CF-CSXV-F/6193108
- https://www.digikey.com/en/products/detail/displaytech/DT024DTFT/6650298
- https://www.digikey.com/en/products/detail/focus-lcds/E22RA-FW280-N/12182136
- https://www.digikey.com/en/products/detail/focus-lcds/E22RB-FW1180-N/12182167
- https://www.digikey.com/en/products/detail/focus-lcds/E24GA-I-CW1000-N/16602032
- https://www.digikey.com/en/products/detail/dlc-display-co-ltd/DLC0240AAM06CB-2/13624834
- Only option? https://4dsystems.com.au/mwdownloads/download/link/id/777/
Game Boy measurements:
This is a common screen for the Game Boy Color:
LCD-39575-003/111
Size: 3.2”
Resulotion: 480X360
Type of Screen: LCD
Type of Flex Ribbon Connector: Clip
In the end, I will use the Game Boy Color shell, because there is more room for modern displays. The Pocket requires displays that are not available anymore.
The best screen for the Game Boy Color is Adafruit's https://www.adafruit.com/product/1774
Screen area measurements:
| Area | Width | Height |
|---|---|---|
| Display area (with screen protection frame) | 4.9cm (49mm) | 4.4cm (44mm) |
| Screen holder | 5.7cm (57mm) | 5.8cm (58mm) |
| Max screen size | 5.9cm (59mm) | 6.5cm (65mm) |
| Area | Width | Height |
|---|---|---|
| Display area (with screen protection frame) | 4.4cm (44mm) | 4cm (40mm) |
| Screen holder | 5.6cm (56mm) | 5cm (50mm) |
| Max screen size | 5.9cm (59mm) | 7.1cm (71mm) |
To configure wifi see the following links:
- https://funconsumertech.com/retropie-wi-fi-setup-an-illustrated-step-by-step-guide/
- https://retropie.org.uk/docs/Wifi/
Configure SSH:
https://retropie.org.uk/docs/SSH/
- Boot to RetroPie
- Enter shell by pressing Ctrl + F4
- cd /boot
- sudo touch ssh
- sudo reboot now
Interesting way to connect the RPi to a PCB: pogo pins
https://www.adafruit.com/product/5382
Grid is configured to 0.5mm (Alt 0.125mm)
| Button | X | Y | Angle |
|---|---|---|---|
| UP | 12.2 | 44.4 | 270 |
| DOWN | 12.2 | 29.4 | 90 |
| LEFT | 4.7 | 36.9 | 0 |
| RIGHT | 19.7 | 36.9 | 180 |
| A | 62.47 | 38.7 | 180 |
| B | 48.42 | 34.21 | 180 |
| START | 40.655 | 16.01 | 0 |
| SELECT | 29.055 | 16.01 | 0 |
To create a virtual keyboard using the GPIOs of the Raspberry Pi, I am using Adafruit's Retrogame software:
https://github.com/adafruit/Adafruit-Retrogame
Note this repository is in maintenance mode.
This is a tutorial on how to install Retrogame:
https://learn.adafruit.com/retro-gaming-with-raspberry-pi/adding-controls-software
In the end, I will use Adafruit's https://www.adafruit.com/product/1774
But this was my investigation:
A good idea might be to use a capacitive touch screen, such as the Waveshare 3.5inch DPI LCD:
DPI displays seem to be more appropriate, since this type of displays have a faster refreshing rate (compared to the SPI displays). Also, the capacitive screen would be useful to use PICO-8 Splore to look for games.
There is selection table at the bottom of this link:
https://www.waveshare.com/product/3.5inch-RPi-LCD-B.htm
This display connects on top of the Raspberry Pi as a hat, which make the handheld device too thick:
This is a tutorial on how to connect and configure a display similar to the one mentioned above:
https://www.youtube.com/watch?v=vCAGzLGTUk4&t=11s
There is also a 4 inch square display, which would be perfect for PICO-8, but it might be too big. It is also more expensive:
https://www.waveshare.com/4inch-DPI-LCD-C.htm
Another option is to use something like the Adafruit PiTFT Plus 320x240 2.8" TFT + Capacitive Touchscreen. The HAT uses the high speed SPI interface on the Pi. This will require a tool called fbcp (framebuffer copy). See Pocket PiGRRL:
https://www.adafruit.com/product/2423
The Adafruit PiTFT 2.2" HAT Mini Kit - 320x240 2.2" TFT - No Touch could also be a good option:
https://www.adafruit.com/product/2315
For the MVP, I might not install a power booster nor a battery!
For the MVP, this wall power supply can be enough:
https://www.adafruit.com/product/1995
Since the battery will provide 3.7V only, we will need a circuit that can boost the battery voltage up to 5V and 1A (for a Raspberry Pi Zero, at least).
We also need to charge (constant current and constant voltage) and a protection circuit (over discharge and short circuit).
Thi video shows how to use the following components:
https://www.youtube.com/watch?v=VczNDDkFiAI
tp4056 MT3608 3.7V lithium battery switch: https://www.adafruit.com/product/805
Interesting videos:
- Power for your electronic projects (does not talk about battery charging): https://www.youtube.com/watch?v=IT19dg73nKU
- DIY LiPo Charge/Protect/5V Boost Circuit: https://www.youtube.com/watch?v=Fj0XuYiE7HU
- How to design a battery charger circuit: https://www.youtube.com/watch?v=XBKOkvwgwNw
The easiest option is to use the Adafruit PAM8302:
https://www.adafruit.com/product/2130
This is the wiring tutorial:
https://learn.adafruit.com/pocket-pigrrl/pam8302
Another option is to make a circuit using the LM4875M/NOPB:
https://www.digikey.com/en/products/detail/texas-instruments/LM4875M-NOPB/1871687
This looks pretty simple, and it is implemented in the Gaboze-Pocaio as well!
Ideas for enclosures:
- Wooden box: https://www.youtube.com/watch?v=iPKIugXvlM4
- PICO-8 handheld: https://www.youtube.com/watch?v=R3GZflUXv0g
- Pocket PiGRRL: https://learn.adafruit.com/pocket-pigrrl/overview
- PiGRRL Zero: https://learn.adafruit.com/pigrrl-zero/overview
- Game Boy Zero: https://www.youtube.com/watch?v=XzYMWNiUN_M&t=229s
- Easier Game Boy Zero with parts and diagrams: https://www.youtube.com/watch?v=KfKn2JdnxF0
- TurtlePi: https://www.youtube.com/watch?v=BnAuwz3R98o
- Just a controller: https://www.youtube.com/watch?v=1k49VVNHvtU
- No battery: https://www.youtube.com/watch?v=IP3QVGmd_90 and https://www.youtube.com/watch?v=VYeIR5n5Few
- A PCB like the one I am imagining: https://www.youtube.com/watch?v=pEI89ICLwIE and the GitHub repo: https://github.com/Gaboze-Pocaio/Round-2 and https://github.com/32teeth?tab=repositories
- Retro-esp32: https://github.com/retro-esp32/RetroESP32-Hardware
- SAMEBOY (pretty cool project, but no open sourced): https://www.youtube.com/watch?v=S-_VMUlxPx4 and https://www.youtube.com/watch?v=WAgPQLskKko.
- SAMEBOY idea for the display: https://youtu.be/CCwOafAE-Js?t=698
- CircuitPython Deshipu projects: https://hackaday.io/project/186921-game-22
- PiOCKET Tiny: https://hackaday.io/project/21553-pi0cket-tiny and https://www.youtube.com/watch?v=xnwMN_q6XjE
- Getting started with Eagle Part 1 (Autodesk) - https://www.youtube.com/watch?v=j79RRCUsD2c
- Getting started with Eagle Part 2 (Autodesk) - https://www.youtube.com/watch?v=rboxHQR4OCQ
- Inspecting parts in Eagle (Adafruit): https://www.youtube.com/watch?v=VfyzJXDpCm8
- Eagle cross-reference LABELS: https://electronics.stackexchange.com/questions/334798/what-do-decimal-alphanumeric-suffixes-after-a-slash-mean-in-a-schematic-cross-re
- Copy the PCB outline: https://community.element14.com/products/eagle/f/forum/8069/eagle---how-to-copy-between-board-files
- Copy a component from another library in Eagle: https://www.youtube.com/watch?v=lFzv7pSWjh8
- Create a custom library in Eagle: https://www.youtube.com/watch?v=FWbGdwL3-OU
- Circle board with flat sides: https://www.youtube.com/watch?v=-vxEbdl68Ro
- Game Boy shells scans: https://www.reddit.com/r/Gameboy/comments/sn3k7u/attention_gameboy_modders_and_tinkerers/
- Game Color digital camera patent: https://patents.google.com/patent/US7972216B2/en?q=(gameboy+color)&oq=gameboy+color
- Electronic Product Development MASTERCLASS: https://www.youtube.com/watch?v=LxtdV_6XW6A
- LCD connection types: https://focuslcds.com/LCD-Connection-Types#:~:text=Flexible%20printed%20circuit%20(FPC)%20and,laptops%20and%20mobile%20phone%20displays
- How to solder SMD components: https://www.youtube.com/watch?v=J4L76E1xaME
- Understanding Audio Jack Switches and Schematics: https://www.cuidevices.com/blog/understanding-audio-jack-switches-and-schematics