RaspberryPiBoardBeginners

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Revision as of 02:19, 29 December 2011 by Ghans (talk | contribs) (Writing the image into the SDcard and finally booting GNU/Linux)
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This is the "community" beginners guide for Raspberry Pi's ARM based ultra-low-cost (~15GBP or 25USD) Linux computer for teaching computer programming to children. If something doesn't work or isn't covered in these guides, please feel free to ask on the Forum. But before you ask there, make sure you read the FAQs.

Please note that the Raspberry Pi isn't released yet - this page is a community work in progress in preparation for the launch

So I got this little board, what do I do now?

Finding all the right hardware

You'll need a keyboard, mouse, TV/Monitor with either composite or HDMI input, and if you are using the Model A, a good quality USB hub. Furthermore , make sure you' ve got a powered USB port available - you may use the hub , a laptop or just a USB charger of your mobile phone.

Setting up

You will need a HDMI or Composite cable to connect your Raspberry to the Display/Monitor/TV of your choice.

Composite : Most TVs of the last 20 years. HDMI : Computer screens, and of course nearly all Flat -TVs of the last years.

Note: HDMI will give better results.

Depending on from where you get your power from, you will also need a USB A plug -> USB micro plug cable. (Shipped with many MP3 players )

The Raspberry is useless without software , so we will first put a Operating System an a storage card.

Checking everything is working

Running it for the first time

Already explained down here .

Serial connection

The Serial Port is a simple and uncomplicated method to connect to the Raspberry Pi. The communication depends on byte wise data transmission, is easy to setup and is generally available even before boot time.

First interaction with the board

Connect the serial cable to the COM port in the Raspberry Pi, and connect the other end to the COM port or USB Serial Adapter in the computer.

How please? I'm led to believe it's wired at the board end, so needs an accessible 9?? pin male|female 232 connector, then some sort of serial to usb dongle. Any more information on this please?

Next is this the preferred way to get low level access to the board, or using the usb for kbd and hdmi for screen?

Serial Parameters

The following parameters are needed to connect to the Raspberry. All parameters except Port_Name and Speed are default values and may not need to be set.

  • Port_Name: Linux automatically assigns different names for different types of serial connectors. Choose your option:
    • Standard Serial Port: ttyS0 ... ttySn
    • USB Serial Port Adapter: ttyUSB0 ... ttyUSBn
  • Speed: 115200
  • Bits: 8
  • Parity: None
  • Stop Bits: 1
  • Flow Control: None

The Serial Port is generally usable by the users in the group dialout. To add oneself to the group dialout the the following command needs to be executed with root privileges:

 $useradd -G {dialout} your_name 

Super Easy Way Using GNU Screen

Enter the command below into a terminal window

 screen Port_Name 115200

Super Easy Way Using Minicom

Run minicom with the following parameters:

minicom -b 115200 -o -D Port_Name

Tedious Old-Fashioned Way Using Minicom

Another method to setup minicom is described in the Tincantools Minicom Tutorial

GUI method with GtkTerm

Start GtkTerm, select Configuration->Port and enter the values above in the labeled fields.

Windows Users

Windows Users above Windows XP must download putty or a comparable terminal program. Users of XP and below can choose between using putty and Hyperterminal.

First Dialog

If you get the prompt below, you are connected to the Raspberry Pi shell!

 prompt> #

First command you might want try is "help":

 prompt> # help

If you get some output, you are correctly connected to the Raspberry Pi! Congratulations!

SD card setup

Now we want to use an SD card to install some GNU/Linux distro in it and get more space for our stuff. You can use either an SD or SDHC card. In the latter case of course take care that your PC card reader also supports SDHC. Be aware that you are not dealing with an x86 processor, but instead a completely different architecture called ARM, so don't forget to install the ARM port for the distro you are planning to use.

(to be completed)

Formatting the SD card via the mkcard.txt script

(to be completed)

  1. Download mkcard.txt from ???.
  2. $ chmod +x mkcard.txt
  3. $ ./mkcard.txt /dev/sdx, Where x is the letter of the card. You can find this by inserting your card and then running dmesg | tail. You should see the messages about the device being mounted in the log. Mine mounts as sdc.

Once run, your card should be formatted.

Formatting the SD card via fdisk "Expert mode"

First, lets clear the partition table:

================================================================================
$ sudo fdisk /dev/sdb

Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) 
================================================================================

Print card info:

================================================================================
Command (m for help): p

Disk /dev/sdb: 128 MB, 128450560 bytes
....
================================================================================

Note card size in bytes. Needed later below.

Then go into "Expert mode":

================================================================================
Command (m for help): x
================================================================================

Now we want to set the geometry to 255 heads, 63 sectors and calculate the number of cylinders required for the particular SD/MMC card:

================================================================================
Expert command (m for help): h
Number of heads (1-256, default 4): 255

Expert command (m for help): s
Number of sectors (1-63, default 62): 63
Warning: setting sector offset for DOS compatiblity
================================================================================

NOTE: Be especially careful in the next step. First calculate the number of cylinders as follows:

  • B = Card size in bytes (you got it before, in the second step when you printed the info out)
  • C = Number of cylinders
C=B/255/63/512

When you get the number, you round it DOWN. Thus, if you got 108.8 you'll be using 108 cylinders.

================================================================================
Expert command (m for help): c
Number of cylinders (1-1048576, default 1011): 15
================================================================================

In this case 128MB card is used (reported as 128450560 bytes by fdisk above), thus 128450560 / 255 / 63 / 512 = 15.6 rounded down to 15 cylinders. Numbers there are 255 heads, 63 sectors, 512 bytes per sector.

So far so good, now we want to create two partitions. One for the boot image, one for our distro.

Create the FAT32 partition for booting and transferring files from Windows. Mark it as bootable.

================================================================================
Expert command (m for help): r
Command (m for help): n
Command action
  e   extended
  p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-245, default 1): (press Enter)
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-245, default 245): +50

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): c
Changed system type of partition 1 to c (W95 FAT32 (LBA))

Command (m for help): a
Partition number (1-4): 1
================================================================================

Create the Linux partition for the root file system.

================================================================================
Command (m for help): n
Command action
  e   extended
  p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (52-245, default 52): (press Enter)
Using default value 52
Last cylinder or +size or +sizeM or +sizeK (52-245, default 245):(press Enter)
Using default value 245
================================================================================

Print and save the new partition records.

================================================================================
Command (m for help): p

Disk /dev/sdc: 2021 MB, 2021654528 bytes
255 heads, 63 sectors/track, 245 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

  Device Boot      Start         End      Blocks   Id  System
/dev/sdc1   *           1          51      409626    c  W95 FAT32 (LBA)
/dev/sdc2              52         245     1558305   83  Linux

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still uses the old table. The new table will be used at the next reboot.

WARNING: If you have created or modified any DOS 6.x partitions, please see the fdisk manual page for additional information.
Syncing disks.
================================================================================

Now we've got both partitions, next step is formatting them.

NOTE: If the partitions (/dev/sdc1 and /dev/sdc2) does not exist, you should unplug the card and plug it back in. Linux will now be able to detect the new partitions.

================================================================================
$ sudo mkfs.msdos -F 32 /dev/sdc1 -n LABEL
mkfs.msdos 2.11 (12 Mar 2005)

$ sudo mkfs.ext3 /dev/sdc2
mke2fs 1.40-WIP (14-Nov-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
195072 inodes, 389576 blocks
19478 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=402653184
12 block groups
32768 blocks per group, 32768 fragments per group
16256 inodes per group
Superblock backups stored on blocks: 
       32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: 
================================================================================

All done!

NOTE: For convenience, you can add the -L option to the mkfs.ext3 command to assign a volume label to the new ext3 filesystem. If you do that, the new (automatic) mount point under /media when you insert that SD card into some Linux hosts will be based on that label. If there's no label, the new mount point will most likely be a long hex string, so assigning a label makes manual mounting on the host more convenient.

Writing the image into the SDcard and finally booting GNU/Linux

The easiest way to do this is to use PiCard. It even saves you from some hassles explained above. You will need your SD card + reader and a Linux pc to use PiCard. After that , just plug the card into the Raspberry.

Setting up the boot args

Wire up your Raspberry Pi and power it up

Connect the Raspberry Pi to the screen using either the HDMI or composite video cable. Connect the Keyboard and Mouse and finally the power. Now you've got to be PATIENT, first boot takes an extremely long time (probably - certainly true for most other development boards and distros ;)).

Software development/proving

What kind of software development and testing loop has been proven effective please, from someone who'se been there and done it?

For me (and others hopefully) that would be very useful.


Further reading

The main Raspberry Pi resources are:

Thanks to

  • Nabax, _vlad, jkridner, ds2 and the other BeagleBoard wiki contributors on elinux.org for an excellent BeagleBoardBeginners resource, which we used as the template for this page.