Pico-8 on the Raspberry Pi with Game HAT

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I’ve been playing with Pico-8 (https://www.lexaloffle.com/pico-8.php) a lot
lately. I’ve got a small Pico-8 project site to launch soon, but in the mean
time I’m more occupied with getting Pico-8 running on things.

Enter Raspberry Pi, and with it the Waveshare Game HAT
(https://www.waveshare.com/wiki/Game_HAT) – this is a nifty bit of kit. A
screen, controls, and battery circuit that you just plug a Raspberry Pi in to,
and voila you have a portable games console.

I’ve got mine set up with Retropie (https://retropie.org.uk/) and this works
with the Game HAT pretty much out of the box.

Here are the tweaks needed:

Configure the display in your /boot/config.txt

This seems to vary from one Game HAT to another
(according to the Retropie forum (https://retropie.org.uk/forum/topic/20308/waveshare-game-hat-thoughts/9))
but I found that the following config lines worked when added to the end of the
config.txt:

framebuffer_width=512
framebuffer_height=384
hdmi_group=2
hdmi_mode=87
hdmi_cvt=512 384 60

Configure the buttons

The buttons on the Game HAT will work if you install the mk_arcade_joystick_rpi
driver in ~/RetroPie-Setup/retropie_setup.sh and then edit
/etc/modprobe.d/mk_arcade_joystick_rpi.conf to contain:

options mk_arcade_joystick_rpi map=5 gpio=5,6,13,19,21,4,26,12,23,20,16,18

Installing Pico-8

This is straight-forward. First you download the Raspberry Pi zip from your
Pico-8 downloads page, extract it to your home directory, and install wiringpi:

# get Pico-8
$ cd
$ wget <your url to pico-8_0.1.11g_raspi.zip>
$ unzip pico-8_0.1.11g_raspi.zip

# install wiringpi
$ sudo apt install wiringpi

Boot to Pico-8 (and Retropie while holding L)

There are all sorts of approaches that people have detailed elsewhere online to
launch Pico-8 from the Retropie launcher, but I prefer the approach of
configuring this install to be Pico-8 first, and then Retropie only if we’re
holding the L shoulder button at boot. This took some fiddling, but it’s quite
elegant:

First, edit your /etc/profile.d/10-retropie.sh, you can do this over ssh and run
sudo nano /etc/profile.d/10-retropie.sh. Replace the contents with this:

# launch our autostart apps (if we are on the correct tty)
if [ "`tty`" = "/dev/tty1" ] && [ "$USER" = "pi" ]; then
        # if holding L shoulder button, start retropie
        if [[ "$(gpio -g read 23)" = "0" ]]; then
          bash "/opt/retropie/configs/all/autostart.sh"
        else
        # otherwise start pico8 by default
          /home/pi/pico-8/pico8 -height 320 -width 480 -splore && sudo reboot
        fi
fi

We’re using the gpio command from wiringpi to check the value of GPIO pin 23
(L shoulder button on the Game HAT). If it’s 0 (pressed) we launch the usual
Retropie autostart.sh, otherwise we default to running Pico-8.

With the Pico-8 command, I’m specifying the output resolution and launching it
with -splore to give us a games menu. The && sudo reboot bit means that if you
exit Pico-8 using the menu options, it will then reboot the Raspberry Pi so you
can get back to Pico-8 or hold L and start with Retropie.

And that’s it. If you want to make the most out of this you’ll need to have your
Wi-fi configured in Retropie. There are loads of great games on Pico-8 to enjoy,
and they all work really nicely with the Game HAT controls. If you plug a
keyboard in you can even create your own games!

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Published February 10, 2019

Generated from the original post:
https://blog.omgmog.net/post/pico8-on-the-raspberrypi-with-gamehat/


Max Glenister is an interface designer and senior full-stack developer from
Oxfordshire. He writes mostly about front-end development and technology.

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