Raspberry Pi links

Playing with Raspberry Pi I have collected a bunch of more or less useful links, so I decided to put them all together.

Initial re-partitioning

At the time of this writing the standard Debian images (stable) distributed from the official Raspberry Pi website were built for 2GB SD cards. It is possible to copy them to larger cards and it will work but space above 2GB will be wasted.

There are a few simple steps to re-partition the card after the first boot.

Images:

http://raspberrypi.org/downloads/

Step by step:

https://projects.drogon.net/raspberry-pi/initial-setup1/

In short:

printf "d\n3\nd\n2\nn\np\n2\n157696\n\nw\n" | sudo fdisk -cu /dev/mmcblk0
sudo shutdown -r now
sudo resize2fs /dev/mmcblk0p2

Troubleshooting

http://elinux.org/R-Pi_Troubleshooting

GPIO

How to install:

cd /tmp
wget http://raspberry-gpio-python.googlecode.com/files/RPi.GPIO-0.2.0.tar.gz
tar xzvf RPi.GPIO-0.2.0.tar.gz
cd tar xzvf RPi.GPIO-0.2.0
python setup.py install

Sample program:

import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
pin = 4
GPIO.setup(pin, GPIO.OUT)
while True:
    GPIO.output(pin, True)
    GPIO.output(pin, False)

Benchmarking Raspberry Pi GPIO speed

http://codeandlife.com/2012/07/03/benchmarking-raspberry-pi-gpio-speed/

Example with 2 LEDs

https://projects.drogon.net/raspberry-pi/gpio-examples/tux-crossing/2-two-more-leds/

GPIO Port on the Raspberry Pi

http://chrishatton.org/archives/88

SPI/I2C 3.2 kernel

This kernel is based the 3.2 branch. It comes with I2C drivers and a bunch of staging drivers (for example, WiFi).

http://bootc.net/projects/raspberry-pi-kernel

I2C

Quick2Write

Linux I2C interface

http://kernel.org/doc/Documentation/i2c/dev-interface

I2C examples

Example I2C Code

echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device

I2C and the Raspberry Pi

Explanations why and how I2C was added to BootC RPi kernel:

http://bootc.net/archives/2012/05/19/i2c-and-the-raspberry-pi/

MCP23017 I2C IO expander

http://nathan.chantrell.net/20120519/raspberry-pi-and-the-mcp23017-i2c-io-expander/

Complete I2C setup on Raspberry Pi

http://robot-electronics.co.uk/files/rpi_i2c_setup.doc

Set up for using i2c with Raspberry Pi running the standard Debian squeeze distribution.

sudo dpkg-reconfigure tzdata
sudo apt-get update
sudo apt-get upgrade 
sudo apt-get install ca-certificates

Install hexxeh’s rpi-upgrade tool https://github.com/Hexxeh/rpi-update#readme:

sudo wget http://goo.gl/1BOfJ -O /usr/bin/rpi-update
sudo chmod +x /usr/bin/rpi-update
sudo apt-get install git-core

sudo rpi-update

Restart rpi for updates to finish:

sudo shutdown -r now

Download Chris Boots’s kernel with the i2c drivers in as a Debian package from his website http://bootc.net. Navigate to where the Debian package was saved using command line and install the Debian package.

dpkg -i linux-image-3.2.18-rpi1+_5_armel.deb

Copy /boot/vmlinuz-3.2.18rpi1+ to /boot/kernel.img:

sudo cp /boot/vmlinuz-3.2.18rpi+ /boot/kernel.img

Restart RPi again:

sudo shutdown -r now

Download i2c-tools:

sudo apt-get install i2c-tools

If you run ls /dev/i2c* you will not be able to see any i2c ports (e.g. /dev/i2c-0) listed. At start up the i2c ports will not be active. Make it active using modprobe:

sudo modprobe i2c-dev

Now look to see if your i2c ports exist in /dev:

ls /dev/i2c*
i2cdetect -l
dmesg | grep i2c

You should see two i2c ports listed named /dev/i2c-0 and /dev/i2c-1. /dev/i2c-0 is the one we will be using. Another way of listing them is to run i2cdetect -l (a tool that came with the i2c-tools you installed earlier).

Change permissions of the i2c-0 port to let you access:

sudo chmod 666 /dev/i2c-0

You should now be able to download and run some of our example c code. You will need to modprobe i2c-dev and change the permissions of the i2c port every time you boot up as these setting are not saved by default.

Checking Firmware Version

Firmware should be up-to-date. Its update is harmless and cannot brick your RPi.

/opt/vc/bin/vcgencmd version

RPI update

Method 1

https://github.com/Hexxeh/rpi-update

wget https://raw.github.com/Hexxeh/rpi-update/master/rpi-update -O /usr/bin/rpi-update && chmod +x /usr/bin/rpi-update

sudo apt-get install ca-certificates
rpi-update

Method 2

http://iroylabs.blogspot.co.uk/2012/06/raspberrypi-mouse-and-keyboard-does-not.html

wget https://raw.github.com/Hexxeh/rpi-update/master/rpi-update
chmod +x rpi-update
mv rpi-update /usr/bin/rpi-update
sudo rpi-update

Keeping Raspberry Pi fresh

http://wrightrocket.blogspot.co.uk/2012/06/keeping-your-raspberry-pi-fresh.html

USB to serial cable

Olimex USB-SERIAL-CABLE Olinuxino console cable alternative to Raspberry Pi.

three wires for Breadboard connection
SERIAL output 3.3V voltage levels
GND=BLUE, RX(INPUT)=GREEN, TX(OUTPUT)=RED

BLUE (GND) -> 0v GREEN (RX) -> GPIO 14/TxD (BCM), or 15 (wiringPi) RED (TX) -> GPIO 15/RxD (BCD), or 16 (wiringPi)

Driver for Mac OSX Lion

http://xbsd.nl/2011/07/pl2303-serial-usb-on-osx-lion.html

cd /tmp
wget http://xbsd.nl/~martijn/log/osx-pl2303.kext.tgz
tar xvzf osx-pl2303.kext.tgz
cd osx-pl2303.kext
sudo cp -R osx-pl2303.kext /System/Library/Extensions/
cd /System/Library/Extensions
chmod -R 755 osx-pl2303.kext
chown -R root:wheel osx-pl2303.kext
cd /System/Library/Extensions

kextload ./osx-pl2303.kext
kextcache -system-cache

Check:

kextstat -b nl.bjaelectronics.driver.PL2303

Index Refs Address            Size       Wired      Name (Version) <Linked Against>
   74    0 0xffffff7f808ee000 0xb000     0xb000     nl.bjaelectronics.driver.PL2303 (1.0.0d1) <73 34 5 4 3>

Unload the driver (if needed)

Check “kextstat” first, and if “nl.bjaelectronics.driver.PL2303” is there, it can be unloaded by:

sudo kextunload /System/Library/Extensions/osx-pl2303.kext/

Driver as a package

http://changux.co/osx-installer-to-pl2303-serial-usb-on-osx-lio

PL-2303 cables on Mac

http://planet-rcs.de/article/mac_serial_port/

WiFi

http://raspberrywifi.com/

ASUS N10 WiFi adaptor

Kernel 3.2.21-rpi1+ already has this driver, but it requires firmware.

Add the following line to /etc/apt/sources.list:

deb http://backports.debian.org/debian-backports squeeze-backports non-free
Update the package index:

sudo apt-get update
Install firmware-realtek deb package:

sudo apt-get install firmware-realtek