On my home network, some important jobs are performed by little ARM computers.

AirPlay to sound system

The house came with a decent sound system wired in. The receiver can take 1/8” stereo input — from AirPlay, with help from a decade-old Raspberry Pi 1 Model B Rev 2.

1. Prepare disk

With a 4GB SD card, from macOS:

$ diskutil list    # inspect output
$ SDCARD=disk6
$ diskutil unmountDisk ${SDCARD}
$ links https://raspi.debian.net/tested-images/
$ DISKIMAGE=20231109_raspi_1_bookworm.img.xz
$ fetch https://raspi.debian.net/tested/${DISKIMAGE}
$ xzcat ${DISKIMAGE} \
  | sudo dd of=/dev/r${SDCARD} bs=64k oflag=sync status=progress
$ diskutil eject ${SDCARD}

2. First boot

Place the RPi somewhere convenient. Connect SD card, keyboard, HDMI, Ethernet, and power. Log in as root, no password:

# apt update
# apt -y install etckeeper
# cd /etc
# git branch -M main
# apt -y install sudo
# visudo    # for the sudo group, insert NOPASSWD: before the final ALL
# useradd -m -G sudo -s /bin/bash schmonz
# passwd schmonz
# exit

Log in as schmonz:

$ sudo passwd root
$ sudo sh -c 'echo 127.0.1.1 schleierplay >> /etc/hosts'
$ sudo hostnamectl hostname schleierplay
$ sudo ln -sf /usr/share/zoneinfo/US/Eastern /etc/localtime
$ sudo etckeeper commit -m 'Set root password, hostname, and timezone.'
$ sudo apt -y install shairport-sync
$ sudo vi /etc/shairport-sync.conf
$ sudo etckeeper commit -m 'Set AirPlay name.'
$ sudo shutdown -h now

3. Deployment

Raspberry Pi (with green case) _in situ_

Place the RPi where it’ll live. Connect audio cable, Ethernet, and power.

$ ssh-copy-id schleierplay.local

4. Usage

Make sure receiver is set to AUX input. Use AirPlay.

5. Maintenance

As with any Debian:

$ ssh schleierplay.local -t 'sudo apt update && sudo apt -y upgrade && sudo apt -y autoremove'

To back up /etc, git push it someplace trustworthy and private.

6. Wishlist

I’d rather run NetBSD, but on 10.0 with shairport-sync, I saw a lot of AirPlay Speaker Not Available: 'House' is being used by someone else (even when it wasn’t). I may investigate on another Raspberry Pi with the pre-AirPlay Sonos speaker in my office.


AirPrint to old printer

My ancient USB-only HP LaserJet P1006 remains reliable for our basic needs and we’ve still got a pile of toner cartridges. A friend recently sent me a comparatively beefy Pine A64 board.

1. Prepare disk

With a 4GB SD card, from macOS:

$ diskutil list    # inspect output
$ SDCARD=disk6
$ diskutil unmountDisk ${SDCARD}
$ links https://www.armbian.com/pine64/
$ DISKIMAGE=Armbian_24.5.1_Pine64_bookworm_current_6.6.31_minimal.img.xz
$ fetch https://dl.armbian.com/pine64/archive/${DISKIMAGE}
$ xzcat ${DISKIMAGE} \
  | sudo dd of=/dev/r${SDCARD} bs=64k oflag=sync status=progress
$ diskutil eject ${SDCARD}

2. First boot

Place the A64 somewhere convenient. Connect SD card, keyboard, HDMI, Ethernet, and power. Follow the prompts to set the root password, create a user account, and select a locale. Then continue:

# apt update
# apt -y install etckeeper
# cd /etc
# git branch -M main
# visudo    # for the sudo group, insert NOPASSWD: before the final ALL
# exit

Log in as schmonz:

$ sudo sh -c 'echo 127.0.1.1 schleierprint >> /etc/hosts'
$ sudo hostnamectl hostname schleierprint
$ sudo ln -sf /usr/share/zoneinfo/US/Eastern /etc/localtime
$ sudo etckeeper commit -m 'Set root password, hostname, and timezone.'
$ sudo apt -y install hplip avahi-daemon
$ sudo usermod -a -G lpadmin schmonz
$ sudo etckeeper commit -m 'Make myself a printer admin.'
$ sudo shutdown -h now

3. Deployment

Pine A64 Pi (with black and white case) _in situ_

Place the A64 where it’ll live. Connect printer, Ethernet, and power.

$ ssh-copy-id schleierprint.local
$ ssh schleierprint.local
$ sudo hp-setup -i    # follow prompts, mostly defaults; name the queue 'hpljp1006'
$ sudo etckeeper commit -m 'Add initial hplip config for P1006.'
$ sudo sed -i \
  -e '/^\*ColorDevice: True$/s|True|False|' \
  -e '/^\*OpenUI \*Duplex\/Double-Sided Printing: PickOne$/,/^\*CloseUI: \*Duplex$/s|^|*% |' \
  -e '/^\*OpenUI \*ColorModel\/Output Mode: PickOne$/,/^\*CloseUI: \*ColorModel$/s|^|*% |' \
  /etc/cups/ppd/hpljp1006.ppd
$ sudo etckeeper commit -m 'Correct advertised printer capabilities.'
$ sudo sed -i \
  -e 's|^Info $|Info HP LaserJet P1006|' \
  -e 's|^<Printer |<DefaultPrinter |' \
  -e 's|/Printer>$|/DefaultPrinter>|' \
  /etc/cups/printers.conf
$ sudo etckeeper commit -m 'Name printer and set it as default.'
$ sudo sed -i \
  -e 's|^Listen localhost:631$|Listen 0.0.0.0:631|' \
  -e '/^<Location \/>$/a Allow @LOCAL' \
  -e '/^<Location \/admin>$/a Allow @LOCAL' \
  -e '/^WebInterface /a PreserveJobFiles No' \
  /etc/cups/cupsd.conf
$ sudo etckeeper commit -m 'Let local network talk to CUPS.'
$ sudo systemctl restart cups

On macOS, do not override the generic driver with “HP LaserJet P1006”. You won’t be able to print (with filter failed in the server logs), except that every “Supply Levels” check — including the ones that happen as part of every print job — will produce a piece of paper containing the single line @PJL INFO SUPPLIES.

As I understand it, some versions of CUPS have a server bug where it can’t discern whether incoming data has already been filtered for the target queue: filters converted the data (via application/vnd.cups-raster) to the printer’s native command set (whatever that might be)… but when the job got sent to the CUPS server it was tagged as application/vnd.cups-raster rather than, say, application/octet-stream.

While that discussion is over a decade old, its advice — leave the filtering to the server, and make sure clients don’t do any — has me printing from macOS, iOS, and Windows.

4. Usage

On macOS, add the printer. When it autoselects “Generic PostScript Printer”, leave it (details in sidebar). Print.

On iOS, print.

On Windows, add the printer. Print.

5. Maintenance

As with any Debian:

$ ssh schleierprint.local -t 'sudo apt update && sudo apt -y upgrade && sudo apt -y autoremove'

To back up /etc, git push it someplace trustworthy and private.

6. Wishlist

I’d rather run NetBSD, but neither 10.0 nor -current brought up HDMI. I could try writing NetBSD to an SD card, mounting it from another NetBSD system, setting hostname in rc.conf, adding a non-root user, and then booting the A64 from it in order to do the rest over ssh. (Other systems that also didn’t bring up HDMI, wherefore I landed by trial and error on Armbian: FreeBSD 14, OpenBSD 7.5, Debian 12.)