Starting to write down a few tips for Raspberry Pi

Hardware

To sort out what model of Pi you have, look into /proc/cpuinfo:

'0002' => 'Model B Revision 1.0',
'0003' => 'Model B Revision 1.0 + Fuses mod and D14 removed',
'0004' => 'Model B Revision 2.0 256MB', (Sony)
'0005' => 'Model B Revision 2.0 256MB', (Qisda)
'0006' => 'Model B Revision 2.0 256MB', (Egoman)
'0007' => 'Model A Revision 2.0 256MB', (Egoman)
'0008' => 'Model A Revision 2.0 256MB', (Sony)
'0009' => 'Model A Revision 2.0 256MB', (Qisda)
'000d' => 'Model B Revision 2.0 512MB', (Egoman)
'000e' => 'Model B Revision 2.0 512MB', (Sony)
'000f' => 'Model B Revision 2.0 512MB', (Qisda)

Install the OS

I used NOOBS: download, and selected OS Raspbian. In /etc/apt/sources.list, I use a Raspbian mirror:

# debian mirror in France
deb https://goddess-gate.com/archive.raspbian.org/raspbian/ wheezy main contrib non-free

Firmware

To update the Raspberry Pi Firmware:

rpi-update

USB devices

Sometimes, you need to prevent the USB HID from claiming a given USB device. In that case, put in /boot/cmdline.txt:

usbhid.quirks=0x0fde:0xca01:0x4

Set timezone

raspi-config

Backup

Locate the sdcard: cat /etc/fstab:

proc            /proc           proc    defaults          0       0
/dev/mmcblk0p5  /boot           vfat    defaults          0       2
/dev/mmcblk0p6  /               ext4    defaults,noatime  0       1

To backup the SDcard,

sudo dd if=/dev/mmcblk0p6 of=remote/raspberrypislash.img bs=1M

Audio

/etc/pulse/daemon.conf:

;resample-method = speex-fixed-3

/etc/asound.conf:

pcm.!default {
        type hw
        card 0
}

ctl.!default {
        type hw
        card 0
}


pcm.mmap0 {
    type mmap_emul;
    slave {
      pcm "hw:0,0";
    }
}

pcm.!default {
  type plug;
  slave {
    pcm mmap0;
  }

To set analogical audio output:

sudo amixer cset numid=3 1

Test audio in : /opt/vc/hello_pi/hello_audio To set HDMI audio output:

sudo amixer cset numid=3 2

The standard VLC package (apt-get) did not work, and had to be re-compiled:

To start it:

cvlc --vout omxil_vout

GPIO

GPIO filesystem files

To export a GPIO:

echo 22 > /sys/class/gpio/export

To configure the direction of a GPIO:

sudo sh -c 'echo out > /sys/class/gpio/gpio27/direction'

So, for example, if you need GPIO 17, 22, 23 and 27:

for i in 17 22 23 27
do
  echo $i > /sys/class/gpio/export
  echo out > /sys/class/gpio/gpio$i/direction
done

To enable use of GPIO for the GPIO group:

SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c 'chown -R root:gpio /sys/class/gpio; chmod -R 770 /sys/class/gpio; chown -R root:gpio /sys/devices/virtual/gpio; chmod -R 770 /sys/devices/virtual/gpio'"

GPIO Python library

Installing python GPIO lib (Check for for the latest version):

$ wget https://pypi.python.org/packages/source/R/RPi.GPIO/RPi.GPIO-0.5.11.tar.gz
$ tar zxf RPi.GPIO-0.5.11.tar.gz 
$ cd RPi.GPIO-0.5.11/
$ sudo python setup.py install

Limiting writes on the SDCard

In theory, the number of writes on a SD card is bounded, and if you write too much, it will eventually fail. This is certainly true with old and/or low quality SD cards, I am however unable to say if this is still true with today's SD cards.
Yet, if you want to be sure, it might be a good idea not to write "everything" on your SD card, in particularly some logs or temporary files: a tmpfs is a far nicer and simple solution.
To do this, just specify the mountpoint for the tmp filesystem. For instance, my /etc/fstab mounts /tmp and /var/tmp as 2 tmpfs. The size is specified (and taken on the RAM).

proc            /proc           proc    defaults          0       0
/dev/mmcblk0p5  /boot           vfat    defaults          0       2
/dev/mmcblk0p6  /               ext4    defaults,noatime  0       1
/dev/sda1       /media/usbstick vfat    uid=xbmc,gid=staff,dmask=002      0    2
tmpfs           /tmp            tmpfs   defaults,noatime,nosuid,size=100m      00
tmpfs           /var/tmp        tmpfs   defaults,noatime,nosuid,size=30m       00

There are some other tweaks on this website