Barputer
| Barputer |
|---|
| What: |
| In a hackerspace a computer is needed everywhere, included behind the bar. So this project was born. |
|
| Participants: |
| Koen, Koert, berz, Warddr |
| Category: |
| Electronics |
| Locations: |
| Den Bunker |
Contents |
Function
- It allows everyone to play their favorite music.
- Stock management for the bar
- General purpose computing
Hardware
The computer is situated next to the refrigerator. Its audio jack is connected to the amplifier to play music.
The touchscreen is a 17" LCD which connects using VGA. The touchscreen also has a serial port, which is connected to a serial-to-usb adapter.
Case
It is fancy.
Misc
- We have a serial barcode scanner, but we don't use it at the moment
- Is this still available? Yes!!!
Software
- Berz tried using debian (concerned with the system's reliability) but couldn't get the touchscreen (which isn't supported by the kernel) configured
- The barputer runs Xubuntu, which comes with Utouch, under we got the touchscreen working quickly
Touch
Install the needed packages:
sudo apt-get install xserver-xorg-input-elographics xserver-xorg-input-evdev-dev utouch sudo apt-get install xinput-calibrator
Recognize the device at boot
echo 'inputattach -elo /dev/ttyS2' >> /etc/rc.local
Calibrate the touchscreen, and put the output here: /usr/share/X11/xorg.conf.d/99-calibration.conf
xinput_calibrator
This is the config I last used, but if you've got smaller finger feel free to optimize it:
Section "InputClass" Identifier "calibration" MatchProduct "Elo Serial TouchScreen" Option "Calibration" "4015 -4 6 4026" EndSection
Music
The technical aspect of the setup is documented here, if you just want to play some music, check out How to play music
We use MPD (Music Player Daemon) as a music server. This allows us to use various clients at the same time, including over the network and on portable devices.
MPD can play audio streams. The list of streams is populated by scanning /home/barputer/Music/streams Aditionally MPD scans for music in /home/barputer/Music/shares. However no music is kept on barputer, and we intend to keep it this way. Instead, this directory is dynamically populated by mounting available music directories over the network.
RAF
Raf is the name of the script that mounts the shared music dirs, and is an abbreviation of Remote Audio Folders. It scans the network for available samba shares, keeps only those whose name contains the string 'music' to prevent mounting the wrong shares, mounts and updates the MPD library if necessary. It also scans if all the mounted shares are still accessible and unmounts them if they are not. Raf is invoked automatically by cron, keeping the MPD library up to date.
If you're impatient, you can force a sync by executing the following command on barputer:
# RAF sync
To add music to the MPD library we originally used djmount, a program which automatically mounts UPNP shares. This setup was copied from Whitespace and is documented here.
Forwarding sound through pulseaudio
Pulseaudio has replaced ALSA and OSS quite some time ago as the default sound server on linux. Since pulseaudio has networking built in by default, you can forward sound to barputer instead of your laptop speakers if you are running pulseaudio too (ie: run linux).
The CLI way
PULSE_SERVER=192.168.42.103 rhythmbox
This should start rhythmbox while sending the resulting audio to barputer. Warning: barputer's ip might change.
The GUI way (GNOME)
You will need to have paprefs, pavucontrol and avahi installed. Avahi needs to be running to discover network devices. Launch paprefs and tell pulseaudio to make remote audio servers available locally. Reboot to or restart Pulseaudio. Launch pavucontrol. Under the 'playback' tab you will see all programs playing audio listed. If Avahi detects barputer's pulseaudio server you should be able to select it to play one of these streams
Point of sales & Stock management
Using the vwcr application made by Koert. It's not completely finished yet, but it can be used (and is being used).
Backups
Images
Every once in a while we make a full snapshot. These are full images that can be restored to the drive. The last image was made on 17/05/'12. The images are made using FSarchiver. We can't use Norton Ghost or Clonezilla since they don't have support for EXT4, which we use for barputer's root filesystem. Backup procedure:
- Boot a live cd which has FSarchver (you can use System Resque CD).
- Check the partition's name
- Mount the backup partition on /mnt: mount /dev/sda1 /mnt
- make an archive: fsarchiver savefs --compress=4 /mnt/images$(date +%F) /dev/sdb1
- The first time we used --compress=5, which took a long time. So we should probably use level 4 or even 3.
Incremental
A backup of all the files on the root drive is taken every hour. These backups are rotated. Every fifth hourly backup is kept for 25 hours and is called a 'recent' backup. Every fifth recent backup is kept for 125 hours and called a 'medium' backup. Every fifth medium backup is called an 'old' backup and is kept indefinably. One hour in this context refers to an hour the computer is turned on. The snapshots are made and rotated automatically.
This scheme uses rsync for snapshotting, rsnapshot for rotating, and space usage is kept down using hardlinks (every version of a file is only saved once).
$ sudo du -hs /media/backup/incremental/* 4.0K /media/backup/incremental/counter 3.8G /media/backup/incremental/hourly.0 138M /media/backup/incremental/hourly.1 71M /media/backup/incremental/hourly.2 123M /media/backup/incremental/hourly.3 72M /media/backup/incremental/hourly.4 82M /media/backup/incremental/young.0
TODO
*MOAR DOCUMENTING (on this page and How to play music)
clean up the server for clarity and minimizing diskspaceUninstall unneeded packages (Ubuntu comes with many packages preinstalled we don't need)Organize our directories and files
make a backup image we can roll back to in case of emergencyincremental backups so we can roll back a part of the system if we need to- have barputer power itself on automatically when the space opens
- have barputer power itself off automatically when the space closes
- barputer hangs sometimes when booting, we don't know why
we could use a relay so we don't have to turn the touchscreen's PSU on by hand when booting barputercreating icon for barputer
