Raspberry Pi

Notes

Setup notes

Writing an OS image to the sdcard (or usb drive)

sudo dd bs=4M if=/path/to/os/image of=/dev/mmcblk0 status=progress

Headless wifi setup

Mount the boot partition and create a file called wpa_supplicant.conf with the following contents:

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
    ssid="SSID"
    scan_ssid=1
    psk="PASSWORD"
    key_mgmt=WPA-PSK
}

Enable SSH prior to first boot

Mount the boot partiton and create an empty file called ssh:

touch /path/to/boot ssh

Initial setup

Use the raspi-config utility to set the follwing options as desired:

Changing the default username (pi)

This must be done while logged in as the root user. It cannot be done (with sudo or su) while the pi user is looged in.

To enable root login, edit /etc/passwd, removing the 'x' after the first colon on the line that begins with root:x:.... Also, if attempting this over SSH, the /etc/sshd.conf file will need to be modified, changing the line PermitRootLogin=prohibit-password to PermitRootLogin=yes. Don't forget to revert these changes once the pi user has been renamed.

usermod -l USERNAME pi
usermod -d /home/USERNAME -m USERNAME
groupmod -n USERNAME pi
rm /etc/sudoers.d/010_pi-nopasswd

Disable WiFi Power Managment

Create the file /etc/network/interfaces.d/wlan0 with the following contents:

allow-hotplug wlan0
iface wlan0 inet manual
wireless-power off

List of config.txt options

Miscellaneous config.txt options:

Display

disable_splash=1  # Disable the rainbow splash screen on bootup
lcd_rotate=2  # Rotate lcd displays like the official touchscreen 180 degrees;

LEDs

[pi0]
dtparam=act_led_trigger=none  # Green LED, available triggers are listed in /sys/class/leds/led0/trigger, default is mmc0
dtparam=act_led_activelow=off  # inverts the activity state

[all]
dtparam=act_led_trigger=none  # Green LED, available triggers are listed in /sys/class/leds/led0/trigger, default is mmc0
dtparam=act_led_activelow=off

dtparam=pwr_led_trigger=none  # Red LED, available triggers are listed in /sys/class/leds/led1/trigger, default is default_on
dtparam=pwr_led_activelow=off

Wireless

dtoverlay=disable-bt  # Disable buit-in bluetooth
dtoverlay=disable-wifi  # Disable built-in wifi

Google AIY voice kit v1

Enable the driver:

Edit/Add to /boot/config.txt:

dtoverlay=i2s=on
...
#dtparam=audio=on
...
# Google AIY voice kit v1
dtoverlay=i2s-mmap
dtoverlay=googlevoicehat-soundcard

ALSA configuration:

Create /etc/asound.conf:

options snd_rpi_googlevoicehat_soundcard index=0

pcm.softvol {
    type softvol
    slave.pcm dmix
    control {
        name Master
        card 0
    }
}

pcm.micboost {
    type route
    slave.pcm dsnoop
    ttable {
        0.0 30.0
        1.1 30.0
    }
}

pcm.!default {
    type asym
    playback.pcm "plug:softvol"
    capture.pcm "plug:micboost"
}

ctl.!default {
    type hw
    card 0
}

Reboot after editing asound.conf.

Verify:

Verify that the sound card's output and input is recognized with

aplay -l
arecord -l

Test:

Record a 5 second test.wav with:

arecord -c 2 -f cd -d 5 test.wav

Play test.wav with:

aplay test.wav

Pulseaudio

Install the pulseaudio package, and optionally pulsemixer for volume control. The microphone volume is low under the default ALSA driver, pulseaudio can 'overdrive' the source volume. 200-250% should be sufficent.

After installed, start the pulseaudio server with pulseaudio -D. List sources (inputs) with pactl list sources, note the index # of the soundcard, make sure it's not the null-monitor or loopback from the sink (output). Use that index number to increase the source volume, for example if the source index is #1: pactl set-source-volume 1 250%