Beatboxer

A human-sized drum machine built with a Raspberry Pi, an Adafruit Feather SCORPIO, NeoPixels, and Go.

• Raspberry PI Setup
  • OS
    • First Boot
    • Faster boot
    • Code
    • USB Audio
      • bbox-style sound card
      • baux-style sound card
      • Test
    • Audio support for Go
• Run
• Build
• Auto boot with keyboard attach
  • Auto boot baux
• Connectivity
  • Configure to connect over ethernet
  • Configure the Pi to connect as Wifi AP
    • Switch the Pi back to connecting to the internet with wifi
• Docs
• Credits
• TODO

Raspberry PI Setup

OS

1. Install Raspberry Pi Imager: https://www.raspberrypi.com/software/
2. Choose Raspberry Pi 5, Raspberry Pi OS Lite (64-bit) and USB Mass Storage in the Imager
3. Select:

• Set hostname to raspberrypi
• Set username and password: sig
• Set locale to en_US.UTF-8
• Configure wireless LAN
• Enable SSH: Allow public-key authentication only

First Boot

HOSTNAME=raspberrypi
HOSTNAME=raspberrypi5-2
HOSTNAME=raspberrypi5-3
HOSTNAME=raspberrypi5-4
HOSTNAME=raspberrypi5-5
HOSTNAME=raspberrypi5-6

ssh [email protected]
ssh sig@$HOSTNAME.local
ssh [email protected]

# install packages
sudo apt-get update
sudo sed -i 's/^# *\(en_US.UTF-8 UTF-8\)/\1/' /etc/locale.gen
sudo locale-gen
sudo dpkg-reconfigure locales
sudo apt-get install -y git tmux vim locales

# GITHUB_TOKEN=

git clone https://github.com/siggy/dotfiles.git ~/code/dotfiles
cp ~/code/dotfiles/.local.bash.pi ~/.local.bash
cp ~/code/dotfiles/.curlrc        ~/
cp ~/code/dotfiles/.gitconfig     ~/
cp ~/code/dotfiles/.tmux.conf     ~/
cp ~/code/dotfiles/.vimrc         ~/
cp ~/code/dotfiles/.wgetrc        ~/

sed -i '/^[[:space:]]*helper = osxkeychain/ s/^/#/' ~/.gitconfig

mkdir -p ~/.vim/backups
mkdir -p ~/.vim/swaps
cp -a ~/code/dotfiles/.vim/colors ~/.vim

echo "[[ -s ${HOME}/.local.bash ]] && source ${HOME}/.local.bash" >> ~/.profile

Faster boot

sudo systemctl disable ModemManager.service
sudo systemctl disable NetworkManager-wait-online.service
sudo systemctl disable bluetooth.service
sudo systemctl disable dphys-swapfile.service
sudo systemctl disable fake-hwclock.service
sudo systemctl disable systemd-binfmt.service
sudo systemctl mask sys-kernel-debug.mount sys-kernel-tracing.mount
sudo systemctl mask rpi-eeprom-update
sudo systemctl disable e2scrub_reap.service
sudo dphys-swapfile swapoff
sudo apt-get -y purge modemmanager bluez triggerhappy
sudo apt-get -y autoremove --purge

sudo grep -q 'rootdelay=' /boot/firmware/cmdline.txt \
  || sudo sed -i 's/$/ rootdelay=2 modules-load=dwc2/' /boot/firmware/cmdline.txt

echo "PollIntervalMinSec=600" | sudo tee -a /etc/systemd/timesyncd.conf

Code

curl -L -o /tmp/go1.24.4.linux-arm64.tar.gz https://go.dev/dl/go1.24.4.linux-arm64.tar.gz
sudo rm -rf /usr/local/go && sudo tar -C /usr/local -xzf /tmp/go1.24.4.linux-arm64.tar.gz
export PATH=$PATH:/usr/local/go/bin

mkdir -p ~/code/
git clone https://github.com/siggy/bbox.git ~/code/bbox

USB Audio

bbox-style sound card

For MCSPER USB to 3.5mm Audio Jack Adapter.

Plug in USB audio device and run:

sudo tee /etc/asound.conf > /dev/null <<'EOF'
pcm.!default {
  type plug
  slave.pcm "dmix:Audio,0"
}

ctl.!default {
  type hw
  card "Audio"
}
EOF

amixer
amixer -c 0 scontrols
amixer -c 0 set PCM 95%

baux-style sound card

For Plugable USB Audio Adapter with 3.5mm Speaker-Headphone and Microphone Jack.

Plug in USB audio device and run:

sudo tee /etc/asound.conf > /dev/null <<'EOF'
pcm.!default {
  type plug
  slave.pcm "dmix:Device,0"
}

ctl.!default {
  type hw
  card "Device"
}
EOF

Test

aplay /usr/share/sounds/alsa/Front_Center.wav

Audio support for Go

sudo apt-get install -y libasound2-dev

Run

go run cmd/bbox/main.go --fake-leds

Build

go build -o /home/sig/bin/bbox cmd/bbox/main.go

Auto boot with keyboard attach

cat <<'EOF' >> ~/.profile

if [ "$(tty)" = "/dev/tty1" ]; then
  tmux attach -t bbox || tmux new-session -s bbox "bash -c '/home/sig/bin/bbox; exec bash'"
fi
EOF

sudo mkdir -p /etc/systemd/system/[email protected]
cat <<EOF | sudo tee /etc/systemd/system/[email protected]/override.conf
[Service]
ExecStart=
ExecStart=-/sbin/agetty --autologin sig --noclear %I \$TERM
EOF

sudo systemctl daemon-reload
sudo reboot

Auto boot baux

cat <<'EOF' >> ~/.profile

export MINIAUDIO_ALSA_NO_MMAP=1
if [ "$(tty)" = "/dev/tty1" ]; then
  tmux attach -t bbox || tmux new-session -s bbox "bash -c '/home/sig/bin/baux; exec bash'"
fi
EOF

Connectivity

Configure to connect over ethernet

IP=192.168.2.2
IP=192.168.2.3
IP=192.168.2.4
IP=192.168.2.5
IP=192.168.2.6
sudo nmcli con add type ethernet ifname eth0 con-name eth0-static ipv4.addresses $IP/24 ipv4.method manual
sudo nmcli con up eth0-static

HOSTNAME=raspberrypi
HOSTNAME=raspberrypi5-2
HOSTNAME=raspberrypi5-3
HOSTNAME=raspberrypi5-4
HOSTNAME=raspberrypi5-5
HOSTNAME=raspberrypi5-6
IP=192.168.2.2
IP=192.168.2.2
IP=192.168.2.3
IP=192.168.2.4
IP=192.168.2.5
IP=192.168.2.6
alias pi="ssh sig@$HOSTNAME.local"
alias pieth="ssh sig@$IP"

Configure the Pi to connect as Wifi AP

SSID=sigpi
SSID=sigpi5-2
SSID=sigpi5-3
SSID=sigpi5-4
SSID=sigpi5-5
SSID=sigpi5-6
rfkill list
sudo rfkill unblock wifi
rfkill list
sudo nmcli radio wifi on
sudo nmcli dev wifi hotspot ifname wlan0 ssid $SSID password showmethepi
nmcli dev wifi show-password
sudo nmcli connection modify Hotspot autoconnect yes

From laptop:

HOSTNAME=raspberrypi5-4
ssh sig@$HOSTNAME.local

Switch the Pi back to connecting to the internet with wifi

nmcli connection show
sudo nmcli connection down Hotspot

Docs

docker run --rm \
  --volume="$PWD/docs:/srv/jekyll:Z" \
  --publish 4000:4000 \
  --publish 35729:35729 \
  -it jekyll/jekyll:4.2.2 \
  jekyll serve --source /srv/jekyll --livereload

open http://0.0.0.0:4000/bbox/

Credits

• amplitude courtesy of (https://github.com/johnusher)
• Hardware keyboard courtesy of (https://github.com/kodachi614/macropaw)
• wavs courtesy of (http://99sounds.org/drum-samples/)

TODO

• proper LED simulator