Winter's Fall » DIY

nas server

tallganglyguy — Thu, 31 Dec 2009 02:13:57 +0000

After seeing Jeff Atwood’s recent data loss I had my own nightmare about losing data. Unfortunately for me it involved the loss of all of the photos I’ve taken since 2003. Plus a good deal of other stuff.

So, I set out today to solve my problem. I spent a good deal of time looking at the off-the-shelf products on the market. Every product seemed to have made some drawback that I wasn’t willing to accept. So, I finally caved and built a NAS system. The result is a system that serves all of my purposes and then some, while being energy conscious.

Here is a list of the components that went into the system:

AMD Athlon LE-1640 processor
2GB of RAM (PC-6400)
3x 1.5TB Seagate 5900 RPM drives with 32MB buffer

After assembling all of that I installed Ubuntu Server 9.10 on it. The installation went off without much trouble. I created a RAID-1 volume of 256MB using all three drives for use as /boot. I used the remaining space on the drives to create a RAID5 array. This gave me about 3TB of space to work with. I dedicated this remaining space to LVM and created the following logical volumes:

root (mounts at /) – 30GB formatted XFS
home (mounts at /home) – 10GB formatted XFS
share (mounts as /mnt/share) – 500GB formatted XFS
swap (used as swap) – 8GB
timemachine – 600GB
unallocated – ~1.5TB

The share volume is served up using SAMBA to the various computers in the house (a couple of laptops, an iMac, etc.). The timemachine volume is exported using iSCSI to the iMac for use by TimeMachine.

A quick test showed that sequential writes to the share volume yielded about 130MB/s of sustained throughput on the server. Once I upgrade to a GigE switch I will perform the same test remotely and see what sort of performance I get.

Canon Digital Shutter Release

tallganglyguy — Wed, 02 Jan 2008 23:08:57 +0000

As part of my Projekt365 I realized that I was going to need to buy/make some equipment. The first piece of equipment that will be made is going to be a shutter release for the Canon Digital Rebel (300D). I’m not going to go into great detail of how the Canon shutter release works as it is well documented. However, I will go into detail about the design of my shutter release.

My shutter release is going to be digitally controlled. I have selected the AVR Butterfly Evaluation Kit (link) as the basis for the controller. This evaluation kit provides all of the necessary microcontroller support circuitry as well as a nice LCD screen, and is quite extensible in addition to being a handy form factor. It also provides a nice serial interface for programming so that there is a low barrier to entry for non electrical engineers.

I will be designing a board that nestles underneath the butterfly board to provide my application specific circuitry. This will be a quite simple board comprised of a couple of optocouplers, a 2.5mm stereo headphone jack and inter-board connectors.

The real guts of the whole device will be the firmware running on the Atmel ATmega169 microcontroller. Currently I’m planning to support the following modes of operation:

One-shot manual (don’t know why I need a remote to do this, could just press the button)
One-shot delay (to allow me to run back into the frame to do self-photos)
One-shot exposure timer (for long exposures)
One-shot exposure timer with delay (combines the previous two operating modes)
Time lapse (trigger an arbitrary number of frames at an arbitrary frequency with an arbitrary exposure length)
Light meter (the butterfly has a light dependent resistor on the board!)

The AVR Butterfly has a handy 32KHz crystal on board for driving a real-time clock making all of these operations really easy. The control will be implemented as a state machine to setup the timer components and then fall back to sleep. More documentation will follow as I start whacking at code. I will ultimately open source the hardware and software design once I finish it. Look for more to come!

GPS Receiver

tallganglyguy — Mon, 23 Jul 2007 20:45:12 +0000

After purchasing the Samsung BlackJack I’ve been in search of a “good” GPS receiver. The requirements were as follows:

BlueTooth for use with the BlackJack
RS-232/USB interface for use with a laptop/desktop
Rechargeable Lithium-ion battery pack

I was unable to locate a receiver on the open market that met all of those requirements. So, I turned to developing my own. Looking around I located several components that seemed to offer some promise. First, there is the GPS module that I found at SparkFun Electronics. This is a receiver capable of providing updates at 5Hz, versus the typical 1Hz. While that isn’t a necessity in most applications it is nice have. What makes this module particularly handy is that it features 2 serial ports, which makes hooking it up to both bluetooth and usb very easy. Additionally it appears that both ports can have independent configurations. Then, there is the BlueTooth module also from SparkFun Electronics. This module supports a serial link as well as all sorts of configurable goodies. It is probably over-kill as well as it supports 250k baud communications, stereo audio and a whole host of other features. The design will be topped off with a 2000mAH battery pack, charging circuitry, and an FTDI based USB-to-Serial interface. I’ll post updates as the project progresses and components arrive.