Sawtooth Power Mac G4 Raspberry Pi 4 case configuration files v1

sawtoothv1.md

Okay, here's where we've landed for v1:

• Power button
  • Wired to GPIO3, the default for gpio-shutdown
  • When pressed, does a safe shutdown
• Green power LED
  • Wired to GPIO23
  • Lights up green when the RPi powers on
• Reset button
  • Wired to RUN using a test point pin
  • Hard resets the Pi
  • Also boots the Pi if a safe shutdown was performed but power is still present
• Programmer's button
  • Wired to GPIO22
  • Available for programmatic use
• Yellow sleep LED
  • Wired to GPIO24
  • Available for programmatic use
• Front speaker
  • Connected to amp left channel, amp connected to TRRS jack
  • "frontspeaker" composite mono ALSA device available
  • "Front Speaker Output" mono PulseAudio device available, selectable for "AV Jack" in LXDE PulseAudio volume control widget
  • Plays Power Mac G4 startup sound on boot (after Linux initializes the sound device, which is actually pretty late in the boot process)
• DVD drive
  • Connected to USB 3.0 port
  • Reports as Bus 02.Port 2: Dev 3, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
• Zip disk slot
  • Replaced with SSD bay
  • Connected to USB 3.0 port
  • Reports as Bus 02.Port 1: Dev 2, If 0, Class=Mass Storage, Driver=uas, 5000M
• PSU
  • Connected to ATX PSU switch to control power
  • Powering the RPi4 from a molex connector 5V line to USB-C
    • Power appears stable while running sysbench
  • Powering the amp from a molex connector 5V line to bare wires

Here's the software configuration:

• /opt/4.wav
• /etc/asound.conf
• /etc/systemd/system/bootsound.service
• /home/pi/sawtoothg4.py (for testing the programmer's button and yellow LED)
• /boot/config.txt
• /usr/share/pulseaudio/alsa-mixer/profile-sets/sawtoothg4-frontspeaker.conf
• /etc/udev/rules.d/91-pulseaudio-rpi.rules (this is a copy of /lib/udev/rules.d/91-pulseaudio-rpi.rules to override it)

Todo:

• Plug the old I/O ports
• Bring out the two USB 2.0 jacks
• Bring out the two HDMI jacks
• Bring out the ethernet jack
• Bring out the ATX PSU switch, although this will go away in a v2

Credits:

• Specs: https://everymac.com/systems/apple/powermac_g4/specs/powermac_g4_450.html
• Front panel pinout: https://www.tonymacx86.com/threads/pinout-and-circuit-for-the-g4-sawtooth-switch-cable.50357/
• Front panel pinout: https://forums.macrumors.com/threads/g4-power-switch-panel-pinout.417971/
• PSU pinout: http://atxg4.com/sawtooth.html
• Manual: http://web.archive.org/web/20050329115144/https://manuals.info.apple.com/en/PowerMacG4_PCI-AGPSetup.pdf
• Speaker: https://www.reddit.com/r/hackintosh/comments/1ezmih/anyone_install_an_internal_speaker_in_their/ca6cvi4/
• Speaker: https://www.ebay.com/itm/815-2915-REGAL-APPLE-IMAC-G4-EMC1843-POWERMAC-8-OHMS-2W-INTERNAL-SPEAKER-/223896561604
• DVD: https://www.pioneerelectronics.com/PUSA/Professional/Computer-Drives/DVR-111D
• Identifying power and ground speaker wires: https://soundcertified.com/speaker-wiring-diagram-guide/
• ALSA configuration: http://pi.eggum.net/2013/09/airplay-or-shairport-that-is.html
• ALSA configuration: https://www.raspberrypi.org/forums/viewtopic.php?f=29&t=33431
• Testing audio: https://learn.adafruit.com/usb-audio-cards-with-a-raspberry-pi/testing-audio
• Startup chime: https://forums.macrumors.com/threads/mac-startup-sound-in-wav-format.618119/
• Play chime on boot: https://www.reddit.com/r/raspberry_pi/comments/15m3cy/play_startup_sound_systemd/
• Play chime on boot: https://www.raspberrypi.org/documentation/computers/using_linux.html#creating-a-service

pi@rpi4sawtooth:~ $ cat /etc/asound.conf
pcm.card1 {
  type hw
  card 1
}

ctl.card1 {
  type hw
  card 1
}

pcm.frontspeaker {
  slave.pcm card1
  slave.channels 2
#  type plug
  type route
  ttable {
    # Copy both input channels to output channel 0 (Left).
    0.0 0.5
    1.0 0.5
    # Send nothing to output channel 1 (Right).
    0.1 0
    1.1 0
  }
}

ctl.frontspeaker {
  type hw
  card 1
}

#pcm.!default monocard
pi@rpi4sawtooth:~ $ cat /etc/systemd/system/bootsound.service
[Unit]
Description=Boot Sound
Wants=sound.target
After=sound.target

[Service]
Type=oneshot
RemainAfterExit=no
ExecStart=/usr/bin/aplay /opt/4.wav -D frontspeaker -q

[Install]
WantedBy=multi-user.target
pi@rpi4sawtooth:~ $ cat /home/pi/sawtoothg4/sawtoothg4.py
#!/usr/bin/env python3
import gpiozero
import signal

# Run as root to output to the HDMI display, otherwise will output locally
hdmi = None
try:
    hdmi = open("/dev/console", "w")
except:
    pass

def hello_programmers():
    print("Programmer's button", file=hdmi)
    yellow.toggle()

programmers = gpiozero.Button(22)
yellow = gpiozero.LED(24)

programmers.when_pressed = hello_programmers

signal.pause()
pi@rpi4sawtooth:~ $ tail /boot/config.txt

[pi4]
# Enable DRM VC4 V3D driver on top of the dispmanx display stack
dtoverlay=vc4-fkms-v3d
max_framebuffers=2

[all]
#dtoverlay=vc4-fkms-v3d
dtoverlay=gpio-shutdown
gpio=23=op,dh
pi@rpi4sawtooth:~ $ cat /usr/share/pulseaudio/alsa-mixer/profile-sets/sawtoothg4-frontspeaker.conf
[General]
auto-profiles = yes

[Mapping front-speaker]
description = Front Speaker
device-strings = hw:%f
fallback = yes
priority = 1
direction = output
channel-map = mono,mono
paths-output = analog-output
pi@rpi4sawtooth:~ $ cat /etc/udev/rules.d/91-pulseaudio-rpi.rules
SUBSYSTEM!="sound*", GOTO="end"
ACTION!="change", GOTO="end"
KERNEL!="card*", GOTO="end"
ENV{SOUND_FORM_FACTOR}!="internal", GOTO="end"

DRIVERS=="bcm2835_audio", ATTR{id}=="b1", ENV{PULSE_PROFILE_SET}="rpi-hdmi.conf", GOTO="end"
DRIVERS=="bcm2835_audio", ATTR{id}=="b2", ENV{PULSE_PROFILE_SET}="rpi-hdmi.conf", GOTO="end"
DRIVERS=="bcm2835_audio", ATTR{id}=="Headphones", ENV{PULSE_PROFILE_SET}="sawtoothg4-frontspeaker.conf", GOTO="end"

LABEL="end"
pi@rpi4sawtooth:~ $