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When you plug the Linuxstamp into your host (Linux) machine a device should appear '''/dev/ttyUSB0''' (I think the postfix number will increment as you add more devices). '''/dev/ttyUSB0''' will behave as any other serial port now. '''Minicom''' is the standard program to access the serial port in Linux. The first time you run minicom you will have to be root in order to do the setup, after that you can change the permissions on /dev/ttyUSB0 so any user can run minicom. To enter configuration mode in minicom type '''CTRL-A o''', now scroll down to '''Serial port setup'''. Use the letters to navigate. You will want the device to be '''/dev/ttyUSB0''' and '''Bps/Par/Bits''' to read '''115200 8N1'''. Both hardware and software flow control should be OFF. Connection to the board is important for loading Atmel's tiny program and u-boot, but once the board is working it might not be as important.
 
When you plug the Linuxstamp into your host (Linux) machine a device should appear '''/dev/ttyUSB0''' (I think the postfix number will increment as you add more devices). '''/dev/ttyUSB0''' will behave as any other serial port now. '''Minicom''' is the standard program to access the serial port in Linux. The first time you run minicom you will have to be root in order to do the setup, after that you can change the permissions on /dev/ttyUSB0 so any user can run minicom. To enter configuration mode in minicom type '''CTRL-A o''', now scroll down to '''Serial port setup'''. Use the letters to navigate. You will want the device to be '''/dev/ttyUSB0''' and '''Bps/Par/Bits''' to read '''115200 8N1'''. Both hardware and software flow control should be OFF. Connection to the board is important for loading Atmel's tiny program and u-boot, but once the board is working it might not be as important.
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The default installation of minicom does not automatically include the XModem file transfer module 'sx' which you will need to send files.  It is part of the Linux package named lrzsz ([http://packages.debian.org/lenny/lrzsz lrzsz]).  Just type 'sx' at a command line to see if it is installed.  If not, install the lrzsz package and minicom will find and use 'sx' automatically.
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XModem transfers between Minicom and U-Boot seem to work fine. This means that you can update U-Boot itself as well as the kernel and root file systems using Minicom. However, the built in xmodem in minicom does not seem to work with the hardware bootloader in the AT91RM9200. If you see "Retry 0: NAK on Sector", you have likely hit this problem. The folks at [http://www.koansoftware.com/it/art.php?art=68 Koan] have created a workaround. The one thing you have to do is edit the .c file for the proper serial port ttyUSB0 in my case. (This link does not seem to work any more, does someone have an alternate?)
 
 
XModem transfers between Minicom and U-Boot seem to work fine. This means that you can update U-Boot itself as well as the kernel and root file systems using Minicom after getting U-Boot itself installed via the built-in hardware bootloader in the AT91RM9200.  The bootloader is much more finicky than U-Boot itself, so getting U-Boot installed can be tricky.  Here is my technique:
 
 
 
* Connect the USB cable to LinuxStamp and start minicom from a terminal window.
 
* Boot the LinuxStamp.  You should see CCC... on the minicom console, with a new C every second or two.
 
* Hit Enter twice.  This will stall the bootloader, and the CCC... sequence will stop.  It will also synchronize the USB/serial converter.
 
* Hit Ctrl-A Z S sequence to bring up the file transfer dialog in minicom.  Select XModem and navigate to and select your u-boot.bin file (space bar).
 
* Hit Enter to start the xmodem transfer in minicom.
 
* Press and release the reset pushbutton on the LinuxStamp. The transfer should happen very quickly (a few seconds).
 
* Immediately hit Enter twice when you see the transfer complete.  You *must* do this very quickly (within 1 second or so), and you *must* hit Enter twice. The first time exits the minicom file tranfer dialog, and the second time stalls the newly-loaded U-Boot program so that it doesn't try to auto-run the not-yet-loaded Linux kernel image.
 
 
 
You now have U-Boot in RAM, but not yet in flash. However, U-Boot is a lot nicer than the hardware bootloader, so you can now use U-Boot to load itself into flash by using the U-Boot menu and retransferring the u-boot.bin file again. This second time, the transfer will end up in flash, and will persist through poweroff/on.
 
  
Another alternative is to use HyperTerm on Windows, which works fine with the Hardware boot loader. If you are updating the Darrel Bootloader, note that the loader only has a short delay after you initiate the "receive" (on the loader) after which it send out the "ready to receive" signal. As a result, you'll need to be rather quick to initiate the Xmodem "send" (on HyperTerm). If you are seeing time outs on HyperTerm when you try and send the loader.bin file, you are probably hitting this problem ... you need to have initiated the send before you see the "C" on the screen from the bootloader.
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Another alternative is to use HyperTerm on Windows, which works fine with the Hardware boot loader. If you are updating the Darren Bootloader, note that the loader only has a short delay after you initiate the "receive" (on the loader) after which it send out the "ready to receive" signal. As a result, you'll need to be rather quick to initiate the Xmodem "send" (on HyperTerm). If you are seeing time outs on HyperTerm when you try and send the loader.bin file, you are probably hitting this problem ... you need to have initiated the send before you see the "C" on the screen from the bootloader.
  
 
== nfs & tftp ==
 
== nfs & tftp ==
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* > '''setenv bootcmd 'tftpboot 20800000 uImage; bootm 20800000'''' Sets the boot command to load a image over tftp and boot it
 
* > '''setenv bootcmd 'tftpboot 20800000 uImage; bootm 20800000'''' Sets the boot command to load a image over tftp and boot it
 
* > '''setenv bootargs mem=32M nfsroot=192.168.0.3:/nfs_root ip=192.168.0.51 console=ttyS0,115200n8 rootdelay=1'''
 
* > '''setenv bootargs mem=32M nfsroot=192.168.0.3:/nfs_root ip=192.168.0.51 console=ttyS0,115200n8 rootdelay=1'''
This sets the command line to be passed to the kernel. As you can see it sets the nfsroot, ip address and console
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This sets the command line to be passed to the kernel. As you can see it sets the nfsrot, ip address and console
  
 
== Busybox ==
 
== Busybox ==
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The '''c''' says this is a character device. The '''5''' is the major node, and the '''1''' is the minor node.
 
The '''c''' says this is a character device. The '''5''' is the major node, and the '''1''' is the minor node.
 
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<br><br>
For development the most convenient way to work is by mounting an NFS root file system. Another easy way to deal with the root file system is by mounting it on either a USB drive or SD card, but if you want a stand alone system you will want the root filesystem to come from the onboard Dataflash. There are several steps to do this. The Dataflash on the Linuxstamp is 8MB. A little under 2MB is used for the bootloaders and the Linux kernel. This leaves about 6MB for the filesystem. The filesystem I am working with is about 10MB, so we will need to compress the filesystem. One method of doing this is to use the initramfs function in the kernel. The kernel expects the image to be a gzipped CPIO archive. In the kernel source there are tools to create the CPIO archive. First we must create a file list from our file system (presumedly this is just the root of your current NFS mount).
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For development the most convenient way to work is by mounting an NFS root file system. Another easy way to deal with thre root file system is by mounting it on either a USB drive or SD card, but if you want a stand alone system you will want the root filesystem to come from the onboard Dataflash. There are several steps to do this. The Dataflash on the Linuxstamp is 8MB. A little under 2MB is used for the bootloaders and the Linux kernel. This leaves about 6MB for the filesystem. The filesystem I am working with is about 10MB, so we will need to compress the filesystem. One method of doing this is to use the initramfs function in the kernel. The kernel expects the image to be a gzipped CPIO archive. In the kernel source there are tools to create the CPIO archive. First we must create a file list from our file system (presumedly this is just the root of your current NFS mount).
 
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/!!Remember that you need a 'init' file in /. You can just link to /sbin/init
 
/!!Remember that you need a 'init' file in /. You can just link to /sbin/init
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== 802.11 Wireless Networking ==
 
== 802.11 Wireless Networking ==
 
With the 2.6.27 vanilla kernel the ralink USB driver works very well. I've been using the AZIO AWU254 without any problems.  
 
With the 2.6.27 vanilla kernel the ralink USB driver works very well. I've been using the AZIO AWU254 without any problems.  
 
== GPIO / Hardware Pin I/O ==
 
 
If you need some guidance figuring out how to 'bit twiddle' the GPIO (General Purpose I/O) pins on the at91 processor, here is a simple example with make file.  If you have your arm-linux cross compiler configured with CrossTool just unpack this file into a folder and type 'make' to generate the executable binary.
 
 
* [http://linuxstamp.budgetdedicated.com/downloads/at91_gpio_example.zip at91_gpio_example.zip]
 
 
This example shows how to set and clear output pins read input pins.
 
  
 
== Servos ==
 
== Servos ==
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* [http://balloonboard.org/ Balloon board]
 
* [http://balloonboard.org/ Balloon board]
 
* [http://www.bifferos.com/ Bifferboard]
 
* [http://www.bifferos.com/ Bifferboard]
* [[Linuxstamp II 9260]]
 
  
 
[[Category:Projects]]
 
[[Category:Projects]]

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