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RealMagenBoy.md

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RealMagenBoy!

This document contains notes and instructions on how to make a real physical Gameboy using this emulator, a RaspberryPi, a SPI screen and a couple of buttons!

Compatability

The software have been tested on the following models:

  • Raspberry Pi 4 model B
  • Raspberry Pi zero2 W

Theoritacly the following models should also work:

  • Raspberry Pi 3 model B
  • Raspberry Pi 3 model B+
  • Raspberry Pi 400

Currently MagenBoy isn't fast enough to run on older RPi models

Required parts

  • Fast enough Raspberry Pi (See)
  • An ili9341 spi display - The one I use, can be found on aliexpress or ebay for about 10$
  • Buttons - Tactile switch buttons or soft tactile switch buttons (for the dpad)
  • Resistors - Im not an Electrical engineer but it is recommended to not connect the buttons directly to the GPIO but instead add a resistor to protect the Pi (resource)
  • Jumper cables - to connect all the parts together, (you can solder with a regular wire, but as a software guy I dont like to permemantly connect stuff)

Optional

Not necessary for a working real life gameboy but can make it nicer

  • Prototype PCB - The green flat ones with holes, to connect to buttons to
  • Solderer - to connect the buttons and the resistors to the prototype PCB
  • A case - if you have a case (or a way to make one) it will make it way more awsome

Assembling

Before starting

Rpi sometimes uses BCM numbers and not actual physical pin number, I have tried to be clear when I reffer to BCM pin and to physical pin - for more about What is BCM

Connect the SPI display

Right now Im ignoring the touch control and connecting like this table to the RPi (this note is about the display mentioned in the required parts section, and not fit for any ili9341 display but can be adjusted to match)

lcd | RPi physical pin |   comment
1   |   1              |   power - connected to the 3.3 pin (any 3.3v power pin)
2   |   9              |   ground (any ground pin)
3   |   24             |   spi chip select - connected to the spi0 cs 
4   |   8              |   reset - pin GPIO BCM 14 (any GPIO pin, after changing need to change the software too)
5   |   10             |   dc - pin GPIO BCM 15 (any GPIO pin, after changing need to change the software too)
6   |   19             |   mosi - spi bus write data signal - connected to the spi0 mosi
7   |   23             |   sck - spi bus clock signal - connected to the spi0 sck
8   |   22             |   led - - pin GPIO BCM 25 (any GPIO pin, after changing need to change the software too)
9   |   21             |   miso - spi bus read data signal - connected to the spi0 miso

Warning The RPi peripherals speed is coupled to main CPU speed to in order to get consistent performance it's necessaty setting it a fix value (on the RPi zero2 I found this config best suited)

Edit /boot/config.txt with the following configurations

core_freq=300
core_freq_min=300

Make sure that dtparam=spi is turned of, should be commented out or be like this dtparam=spi=off (MagenBoy interface the SPI peripherlas directly without the linux driver for better transfer times)

Buttons

I created (using the prototypes PCB's and a solderer) 2 PCB's, one for the Dpad and one for A, B, Start, Select buttons, each contains 4 buttons and exposes 6 pins to be connected with a jumper cable, this is just a recommendation and an example of how this should be done.

Notice The code in MagenBoy expect the buttons to be low on idle and high on press

Dpad connection

I used soft tactile buttons here for a better authentic feel

Pin | RPi physical pin |comment
1   | 35               | DPAD up - pin GPIO BCM 19 (any GPIO pin, after changing need to change the software too)
2   | 40               | DPAD left - pin GPIO BCM 21 (any GPIO pin, after changing need to change the software too)
3   | 36               | DPAD down - pin GPIO BCM 16 (any GPIO pin, after changing need to change the software too)
4   | 39               | ground pin (any ground pin)
5   | 38               | DPAD right - pin GPIO BCM 20 (any GPIO pin, after changing need to change the software too)
6   | 17               | power connected to 3.3v (any 3.3v power pin)

A, B, Start, Select

Pin | RPi physical pin | comment
1   | 16               | Select button - pin GPIO BCM 23 (any GPIO pin, after changing need to change the software too)
2   | 15               | Start button - pin GPIO BCM 22 (any GPIO pin, after changing need to change the software too)
3   | 11               | B button - pin GPIO BCM 17 (any GPIO pin, after changing need to change the software too)
4   | 6                | ground pin (any ground pin)
5   | 12               | A button - pin GPIO BCM 18 (any GPIO pin, after changing need to change the software too)
6   | 17               | power connected to 3.3v

You can design the boards any way you want but this how I did it but any change to the data pins in the buttons or the display will result in modification and recompilation of MagenBoy source code

RPi Key bindings

If you followed untill here the bindings we have is:

Joypad RPi BCM
A BCM 18
B BCM 17
Start BCM 22
Select BCM 23
Dpad Up BCM 19
Dpad Down BCM 16
Dpad Left BCM 21
Dpad Right BCM 20

Menu button

As you can see in the images below there is a 9th button, this is the menu button which triggers the menu.

This button can also turn on the RPi if configured correctly.

Configure the Menu button

First we need to understand how the RPi wakeup works.

We need to short the ground with GPIO BCM 3 button, so unlike the other buttons here we go for low on press and high on idle.

In order for the RPi to wake up in press we need to add another configuration to the /boot/config.txt file (thanks to this post)

dtparam=i2c_arm=off

Notice the i2c_arm and not just i2c, both should be disabled (if the regualr i2c is on by mistake)

Configuring pins

Aside from the SPI interface pins all the pins can be configured by changing the correspond value in configuration.rs and recompiling

Compiling MagenBoy

  • install Rust on the RPi
  • Download MagenBoy git clone https://github.com/alloncm/MagenBoy.git
  • Checkout master
  • At project root Run cargo make rpios
  • Make sure it runs: sudo ./target/release/magenboy [path_to_rom]

Running

Edit /etc/rc.local and add the following line

sudo /home/[path_to_magenboy_root_folder]/target/release/magenboy --rom-menu [path_to_roms_folder] --bootrom [path_to_bootrom]

The bootrom flag is not neccessary but can complete the experience, it is also recommended to use MagenBoot for the best experience

Shutdown on exit

In order to shutdown the rpi on magenboy shutdown you can add --shutdown-rpi to the rc.local command

Warning be careful to not get stuck in shutdown loop in case of a configuration error

Now the MagenBoy rom menu will open every time you turn on the RPi!

Plans for the future

  • Sound support - currently the APU is disabled due to the RPi zero2 not being fast enough and not having a normal audio output
  • Power button - There is no easy way to turn on or off the device (other than cutting the power and pluging to power)

Images

Dpad PCB

Front pcb Back pcb

Buttons PCB

Front pcb Back pcb

The setup inside a wood case with gameboy buttons shell

wood setup

The back of the wood setup with a RPi zero2

wood setup inside