OBEE's DIY: October 2013

Wednesday, 23 October 2013

Raspberry Pi Setup As MPD Sever

Setup MPD on Raspberry Pi:
Credit to the tutorial below:
http://hempeldesigngroup.com/embedded/stories/raspberry-pi-setup-as-mpd-sever/

I've some updates on top of it...
1. Download arch linux image from ArchLinux Raspberry Pi page:
http://archlinuxarm.org/platforms/armv6/raspberry-pi

2. Load the image to a SD card with 2G or more. Win32 Disk Imager is recommended:
http://sourceforge.net/projects/win32diskimager/

3. After loading the image, put the card into Pi and power up, wait for 1 minute, then use IP scanner to find the IP address of Pi, just pick one below or google for others.
http://www.eusing.com/ipscan/free_ip_scanner.htm
http://sourceforge.net/projects/ipscan/
http://download.cnet.com/Advanced-IP-Scanner/3000-18508_4-10115592.html

4. Putty to that IP at port 22
http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html

5. login ID is "root", password is "root"

6. Make private key for auto authenticate (optional)
You may follow the tutorial below for detail setup procedure:
http://www.ualberta.ca/CNS/RESEARCH/LinuxClusters/pka-putty.html

7. Change timezone
Run the tzselect script to figure out which timezone you should be in, then note the output – in my case its America/Toronto.
Add the following text to a new file called /etc/profile.d/timezone.sh – this will cause the timezone to be set whenever a user logs in.

TZ='Asia/Hong_Kong

export TZ

Don’t forget to make the new file executable!

chmod 755 /etc/profile.d/timezone.sh

8. Add Alsa sound output

pacman -Sy

pacman -S alsa-utils

9. Install Music Player Daemon (MPD)

pacman -S mpd mpc

10. Add users for MPD

usermod -G audio -a mpd

11. One-time setup for MPD

mkdir -p /var/lib/mpd/music
chown mpd:mpd /var/lib/mpd

mkdir -p /var/log/mpd
touch /var/log/mpd/mpd.log
chown mpd:mpd /var/log/mpd

12. Edit /etc/mpd.conf

Add or uncomment the following:

music_directory         "/var/lib/mpd/music"
playlist_directory "/var/lib/mpd/playlists"
db_file "/var/lib/mpd/mpd.db"
log_file                        "/var/log/mpd/mpd.log"
state_file "/var/lib/mpd/mpdstate"
bind_to_address         "any"

zeroconf_enabled                "yes"
zeroconf_name                   "Pi + ArchLinux"

audio_output {
        type            "alsa"
        name            "On-board Audio"
        device          "hw:0,0"
}

audio_output {
        type            "alsa"
        name            "USB DAC"
        device          "hw:1,0"
}

(A brief summary:
To make sure the directories for music, log, db etc be consistent.
To make sure zero_conf is turned on
To make sure two audio output devices (using alsa) are defined)

12. Test MPD
Open another putty session, run command:

tail -f /var/log/mpd/mpd.log

The above command will outputs the log data generated by MPD which is very useful for troubleshooting

Start MPD:

systemctl start mpd

See if any error message reported in the MPD log file.

12. Enable MPD service and reboot
Make MPD server starts automatically in each reboot.

systemctl enable mpd.service

sync

reboot

Monday, 21 October 2013

Another ground box - My 2nd DIY ground box + power bar

With the power bar running for a month, I decided to further improve it so that it also act as an "earth box". An earth box is just a box with some "stones" inside that absorb free electrons produced by the electronic appliances. We all know that the "ground" of the AC main is just a relative ground with relative zero impedance. It has best effort to provide a zero voltage level with zero impedance to the electronic appliance so that in case of electricity leakage, the electricity will be drawn into earth (a large reservoir of free electrons) instead of going via human body. In realty, it will never be "zero" by all means. The earth box helps a little bit in absorbing (from my understanding) some free electrons so that the earth is "closer" to the ideal case.

The earth box, as you can see below, is just a box with some good conductors and some black stones. There're lot of DIYers doing similar earth box and they use different kinds of stones with different proportion. I don't have any experience in such detail, what I've done so far is just a random event.

A new life for my cubieboard2

With the release of voyage on cubie board 2 (a.k.a Allwinner A20), my A20 gets a new life.

Thanks to Mr. Punky Tse, the Voyage MPD is now being ported into A20 with support of audiophile quality music playback including DSD support. Mr. Pinky emphasised in the release note that "MPD binds to a single core while leaving another core for interrupts, etc.", that's a good idea!

By following the setup guide provided by Punky, I have loaded the Mubox into A20 successfully within 30 minutes. The sound quality is similar to cubox.

After running it for two days non-stop. I decided to give the A20 a solid case so that it can be placed in my Hifi rack safely.

The case is an aluminum alloy metal case with 2mm thickness at the front, rear, top and bottom, 4mm thickness at the sides

First of all, mark the positions for holes...