Anthony’s Blog

I thought documenting my notes and what I’ve leared about the SheevaPlug so far may be useful so I’m putting together a basic HOW-TO.  The documentation from GlobalScale Technology is a great place to start.

Firstly, it will likely come pre-installed with Ubuntu Jaunty Beta, although possibly Gentoo.  Both can run on the plug in addition to FreeBSD.  Wiki explains more.  It also has a good entry on configuring the plug to boot from an SD card rather then the onboard NAND flash.

The forums are a very useful resource as well:

Configuring the USB serial console (Linux & Windows).  My Ubuntu desktop failed to create a /dev/ttyUSB1 on it’s own when plugged in, a simple ‘modprobe ftdi_sio product=0×9e8f vendor=0×9e88′ resolved that.

Give care when flashing partitions or images and make sure you don’t overwrite /dev/mtd0 or /dev/mtdblock0 (1st MB of NAND), it holds the uBoot boot image, the plug cannot boot without it.  Next partition is the Linux kernel image (~1-4mb), and finally a root filesystem image (remainder of the 512MB).

I somehow managed to brick mine at one point, after a fsck and reboot I got a “Verifying Checksum … Bad Data CRC” error and it would not boot.  Playing with it a bit, I managed to get it to boot by tftp’ing a kernel image and mount a root filesystem via NFS.  GST’s documentation and the wiki provide plenty of guidance.  I also had issues getting it to re-flash the kernel image to /dev/mtd1 because the kernel image provided by GST was slightly too big for the default size of mtd1.  Since then I’ve read they have released a new kernel image that fits, but at the time I simply increased the size of mtd1 (to 4mb rather then the default 1mb) by editing the mtdparts setting in uBoot.

It also occured to me that coming up with a makeshift bootmenu might be useful for debugging:

set console 'console=ttyS0,115200 mtdparts=nand_mtd:0x00100000@0x00000000(uBoot)ro,0x00400000@0x00100000(uImage),0x1fb00000@0x00500000(rootfs)'

set boottftp 'tftpboot 0x2000000 $(image_name)'
set bootargs_nfs 'root=/dev/nfs rw'
set boot_nfs 'run boottftp;setenv bootargs $(console) $(bootargs_nfs) nfsroot=$(serverip):$(rootpath) ip=$(ipaddr):$(serverip)$(bootargs_end);bootm 0x2000000'

set bootnand 'nand read.e 0x2000000 0x00100000 0x00500000'
set bootargs_nand 'root=/dev/mtdblock2 rw'
set boot_nand 'run bootnand;setenv bootargs $(console) $(bootargs_nand) ip=$(ipaddr):$(serverip)$(bootargs_end);bootm 0x2000000'

set bootargs_sd 'root=/dev/mmcblk0p1 rw'
set boot_sd 'run bootnand;setenv bootargs $(console) $(bootargs_sd) ip=$(ipaddr):$(serverip)$(bootargs_end);bootm 0x2000000'

set bootcmd 'run boot_sd;'

As I mentioned, the mtdparts I provided are configured for a 4mb mtd1 partition, you may need to modify this.  This thread explains mtdparts better.  All of the other variables such as IP, SERVERIP, etc need to be configured in addition to these listed here.  You will also see it’s set to boot from SD card by default, it can be changed to ‘run boot_nand’ or ‘run boot_nfs’ if you like.

So I’ve decided to disable my weekly Twitter updates after seeing how annoying it would be to read.  I’ve been working on a few things lately, first is a “DIY radar” weather warning system with the help of NOAA WSR-88D radar data, libGD, and Perl.  I recall some very basic image processing algorithms and code I tinkered with in BASIC when I was much younger, but it was very simplistic and this was ages ago.  It’s fun to catch up on some old programming interests.  I’ll throw a post about it together once the code is a bit more complete.

My Linux-based SheevaPlug (embedded Linux in a wall-wart) has been occupying some time as well, tinkering with the Jaunty install and NFS and SSH.  I’m pretty impressed with the capabilities of this so far, despite the fact I managed to partially brick it for awhile. I eventually want to build a Tweet-A-Watt and use my plug for interfacing.  Wiring my 1-wire weather station to the plug makes sense as well.

Found a search add-on for Firefox if you are into electronics – Octopart has a search plugin written for Firefox which can be installed here.  Very handy if you are constantly looking up datasheets or part numbers.

link to octopart’s blog entry