Pi: detailed setup

Some notes I took when I setup the Pi. I have since Imaged the SD card, so I wont have to go through this again

General

1. sudo raspi-config
1. Change hostname
2. Change user pi password
3. Change timezone

Setup darkice

1. sudo apt-get install lame libtwolame0 - to install lame required to have mp3 support
2. install darkice binary package already compiled for mp3 supprt
3. sudo cp /usr/share/doc/darkice/examples/darkice.cfg /etc/ - to configure darkice
4. edit crontab for time script
5. add record and stream scripts to rc.local for starting up at boot

Setup USB sound card

1. modify alsa-base to make USB sound card the first (0) device
2. reboot
3. check that sound card is picked up correctly. Run following commands:
4. cat /proc/asound/cards
5. amixer 
6. arecord -l
7. aplay -l
8.  Set sound levels: alsamixer 
9. arecord -f S16_LE -D hw:0,0 -r 48000 test.wav
10. aplay test.wav

Create seperate FAT32 extension - this useful to store recordings on a seperate partition to prevent / from overfilling, and to make it FAT32 so that it can be mounted in a Windows machine

1. sudo apt-get install dosfstools
2. sudo cfdisk /dev/mmcblk0 - Using the keyboard create a new primary partition in the free space, and change the type to FAT32 which is option 0B (W95 FAT32). Select Write to save the changes, then select Quit.
3. reboot
4. sudo cfdisk /dev/mmcblk0p3
5. sudo mkfs.msdos /dev/mmcblk0p3

Setup 3G USB dongle

1. sudo apt-get install sg3-utils
2. sudo /usr/bin/sg_raw /dev/sr0 11 06 20 00 00 00 00 00 01 00
3. echo 'SUBSYSTEMS=="usb", ATTRS{modalias}=="usb:v12D1p1F01*", SYMLINK+="hwcdrom", RUN+="/usr/bin/sg_raw /dev/hwcdrom 11 06 20 00 00 00 00 00 01 00"' > /etc/udev/rules.d/10-HuaweiFlashCard.rules
4. modify /etc/network/interfaces

Reverse SSH tunnel

1. ssh-keygen -t rsa
2. copy key to server
3. insert ssh reverse command to /etc/rc.local

syslog

webmin

Pi: USB sound card nightmare

As a follow on to the previous post about the raspberry Pi

I bought two USB sound cards from Matrix Warehouse. They were these two C-Media based chipsets:

7.1: http://www.amazon.com/Channel-External-Sound-Audio-Adapter/dp/B007HISGRW/ref=sr_1_3?ie=UTF8&qid=1382967519&sr=8-3&keywords=usb+sound+card
5.1: http://www.amazon.com/Virtual-5-1-surround-External-Sound-Card/dp/B000N35A0Y/ref=pd_bxgy_pc_img_y

The 7.1 was only giving static. It turns out that the mic I was using was broken, but I learned quite abit about Linux sound tool sets.

These posts were very helpfull:
http://computers.tutsplus.com/articles/using-a-usb-audio-device-with-a-raspberry-pi--mac-55876
http://www.raspberrypi.org/forums/viewtopic.php?p=314611#p314611
http://www.linuxcircle.com/2013/05/08/raspberry-pi-microphone-setup-with-usb-sound-card/

the 7.1

dmesg:

    3.303196] usb 1-1.5: new full-speed USB device number 4 using dwc_otg

[    3.434770] usb 1-1.5: New USB device found, idVendor=0d8c, idProduct=013c

[    3.449598] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=0

[    3.473047] usb 1-1.5: Product: USB PnP Sound Device

[    3.479635] usb 1-1.5: Manufacturer: C-Media Electronics Inc.      

[    3.513315] input: C-Media Electronics Inc.       USB PnP Sound Device as /devices/platform/bcm2708_usb/usb1/1-1/1-1.5/1-1.5:1.3/input/input0

[    3.551191] hid-generic 0003:0D8C:013C.0001: input,hidraw0: USB HID v1.00 Device [C-Media Electronics Inc.       USB PnP Sound Device] on usb-bcm2708_usb-1.5/input3

[    3.997860] udevd[156]: starting version 175

[    6.413474] bcm2708-i2s bcm2708-i2s.0: Failed to create debugfs directory

[    6.848620] usbcore: registered new interface driver snd-usb-audio

pi@pi-roshnee-lm ~/recordings $ cat /proc/asound/cards 

 0 [Device         ]: USB-Audio - USB PnP Sound Device

                      C-Media Electronics Inc. USB PnP Sound Device at usb-bcm2708_usb-1.5, full spee

 1 [ALSA           ]: bcm2835 - bcm2835 ALSA

                      bcm2835 ALSA

pi@pi-roshnee-lm ~/recordings $ lsusb 

Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. 

Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. 

Bus 001 Device 004: ID 0d8c:013c C-Media Electronics, Inc. CM108 Audio Controller

pi@pi-roshnee-lm ~/recordings $ amixer 

Simple mixer control 'Speaker',0

  Capabilities: pvolume pswitch pswitch-joined penum

  Playback channels: Front Left - Front Right

  Limits: Playback 0 - 151

  Mono:

  Front Left: Playback 136 [90%] [-2.88dB] [on]

  Front Right: Playback 136 [90%] [-2.88dB] [on]

Simple mixer control 'Mic',0

  Capabilities: pvolume pvolume-joined cvolume cvolume-joined pswitch pswitch-joined cswitch cswitch-joined penum

  Playback channels: Mono

  Capture channels: Mono

  Limits: Playback 0 - 127 Capture 0 - 16

  Mono: Playback 98 [77%] [18.37dB] [off] Capture 14 [88%] [20.83dB] [on]

Simple mixer control 'Auto Gain Control',0

  Capabilities: pswitch pswitch-joined penum

  Playback channels: Mono

  Mono: Playback [on]

pi@pi-roshnee-lm ~ $ aplay -l

**** List of PLAYBACK Hardware Devices ****

card 0: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

card 1: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]

  Subdevices: 8/8

  Subdevice #0: subdevice #0

  Subdevice #1: subdevice #1

  Subdevice #2: subdevice #2

  Subdevice #3: subdevice #3

  Subdevice #4: subdevice #4

  Subdevice #5: subdevice #5

  Subdevice #6: subdevice #6

  Subdevice #7: subdevice #7

card 1: ALSA [bcm2835 ALSA], device 1: bcm2835 ALSA [bcm2835 IEC958/HDMI]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

pi@pi-roshnee-lm ~ $ arecord -l

**** List of CAPTURE Hardware Devices ****

card 0: Device [USB PnP Sound Device], device 0: USB Audio [USB Audio]

  Subdevices: 1/1

  Subdevice #0: subdevice #0

pi@pi-roshnee-lm ~/pi_scripts $ arecord -f S16_LE -c1 -r44100 -t wav test.wav

Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono

^CAborted by signal Interrupt...

pi@pi-roshnee-lm ~/pi_scripts $ aplay test.wav 

Playing WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono

pi@pi-roshnee-lm ~/recordings $ arecord -D plughw:0 -r 48000 test.wav

Recording WAVE 'test.wav' : Unsigned 8 bit, Rate 48000 Hz, Mono

^CAborted by signal Interrupt...

pi@pi-roshnee-lm ~/recordings $ arecord -D plughw:0 -r 16000 test.wav

Recording WAVE 'test.wav' : Unsigned 8 bit, Rate 16000 Hz, Mono

^CAborted by signal Interrupt...

pi@pi-roshnee-lm ~/recordings $ arecord -f S16_LE -D plughw:0,0 -r 48000 test.wav

Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono

^CAborted by signal Interrupt...

pi@pi-roshnee-lm ~/recordings $ 

pi@pi-roshnee-lm ~/recordings $ cat /boot/cmdline.txt p. 

dwc_otg.lpm_enable=0 dwc_otg.speed=1 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

pi@pi-roshnee-lm ~/recordings $ 

Bandwidth allocation sizing

When trying to calculate bandwidth allocation for a particular protocol, you would need to understand what the size of the actual payload/data is, then calculate what the bottom layer headers would add as overhead. Also, you would need to know what a particular data/payload would measure on Data Links (Layer 2), e.g. Ethernet, Ethernet 801.1Q (VLAN), HDLC, PPP, Frame Relay, Fiber

The typical example is a G.729 voice packet. Just the payload of the packet is 8 kbits, then we add the overheads of the lower layers:

		Overhead Byes/sec	Total
	G729	20	20
Layer 5	RTP	12	32
Layer 4	UDP	8	40
Layer 3	IP	20	60
Layer 2	Ethernet	38	98

Some links I came across:
http://www.techrepublic.com/blog/linux-and-open-source/use-wireshark-to-inspect-packets-on-your-network/
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml
http://sd.wareonearth.com/~phil/net/overhead/
http://aconaway.com/2011/01/10/network-protocol-overhead/


http://networkengineering.stackexchange.com/questions/2793/bandwidth-calculation-for-protocol-over-different-data-physical-links
http://networkengineering.stackexchange.com/questions/2789/wireshark-protocol-hierarchy-explanation