MightyOhm

Video: Staver Electromechanical Vane Display

Jeff — Thu, 02 Sep 2010 20:02:09 +0000

Here’s another neat video from Brian Stuckey of ineedcaffeine.com.

If anyone knows where to find more of these displays, I would love to get my hands on some!

Staver Electromechanical Vane / Flip 7 Segment Display from Brian Stuckey on Vimeo.

Macro video of a hard drive in use

Fix for broken avr-size in Ubuntu 10.04 (Lucid Lynx)

Jeff — Wed, 01 Sep 2010 03:17:29 +0000

If you have never used it before, avr-size is a very useful command that does a relatively simple thing – it tells you how large your compiled avr-gcc programs are. This is very useful knowledge when you are trying to fit as much code as possible into a part with only a few K of flash memory. Additionally, the actual flash footprint of an AVR program is not something you can easily distill from a .hex file. Hex files are usually much larger than the actual compiled code due to the overhead of that file format.

avr-size comes with the binutils-avr package in Ubuntu (and is installed as part of WinAVR and CrossPack on Windows and OSX, respectively). Unfortunately, Ubuntu 10.04 (Lucid Lynx) ships with a broken version of avr-size that doesn’t include the necessary patches to support the AVR.

To see if your avr-size is working, open a Terminal in Lucid and try executing this command on a compiled avr-gcc .elf file of your choice:

avr-size -C --mcu=attiny2313 main.elf

You’ll probably see something like this:

avr-size: invalid option -- 'C' Usage: avr-size [option(s)] [file(s)] Displays the sizes of sections inside binary files If no input file(s) are specified, a.out is assumed The options are: -A|-B --format={sysv|berkeley} Select output style (default is berkeley) -o|-d|-x --radix={8|10|16} Display numbers in octal, decimal or hex -t --totals Display the total sizes (Berkeley only) --common Display total size for *COM* syms --target= Set the binary file format @ Read options from -h --help Display this information -v --version Display the program's version avr-size: supported targets: elf32-avr elf32-little elf32-big srec symbolsrec verilog tekhex binary ihex

Bad news, but it’s not surprising. You have the broken version of avr-size that comes with binutils-avr for Lucid.

The solution:

I was able to fix this issue by installing the binutils-avr package for Debian Squeeze, an approach I learned about from this Ubuntu bug report.

To download the Debian binutils-avr package, either go to the Debian package repository or execute this command:

wget "http://ftp.us.debian.org/debian/pool/main/b/binutils-avr/binutils-avr_2.20.1-1_amd64.deb"

Now install the package by double clicking on it or executing:

sudo dpkg -i binutils-avr_2.20.1-1_amd64.deb

If you tell Ubuntu to “hold” the package you just installed, it should stop trying to revert to the broken version in the Lucid repository every time you run a system update:

echo "binutils-avr hold" | sudo dpkg --set-selections

You can check the hold status by running

sudo dpkg --get-selections | grep binutils-avr

The status should be shown as “hold” (not “install”).

Now if you run avr-size, you should see the special AVR option ‘-C’ is now present.

jkeyzer@atom:~$ avr-size --help

Usage: avr-size [option(s)] [file(s)] Displays the sizes of sections inside binary files If no input file(s) are specified, a.out is assumed The options are: -A|-B|-C --format={sysv|berkeley|avr} Select output style (default is berkeley) --mcu= MCU name for AVR format only -o|-d|-x --radix={8|10|16} Display numbers in octal, decimal or hex -t --totals Display the total sizes (Berkeley only) --common Display total size for *COM* syms --target= Set the binary file format @ Read options from -h --help Display this information -v --version Display the program's version avr-size: supported targets: elf32-avr coff-avr coff-ext-avr elf32-little elf32-big srec symbolsrec verilog tekhex binary ihex

Report bugs to

You can also test it out on a compiled .elf file:

jkeyzer@atom:~$ avr-size -C --mcu=attiny2313 main.elf

AVR Memory Usage ---------------- Device: attiny2313

Program: 2008 bytes (98.0% Full) (.text + .data + .bootloader)

Data: 23 bytes (18.0% Full) (.data + .bss + .noinit)

It works! You now have a working avr-size command for Ubuntu.

There is a good chance this package will eventually be fixed in the Lucid repository, but based on the bug report above, it could be a while (2012?) before we see an update. Until then, installing the Debian package seems to be a good solution.

If anyone reading this is close to the Ubuntu package maintainers, can you please kick them about this issue?

Run avrdude on Ubuntu without root

Ahh, that’s better!

Jeff — Mon, 30 Aug 2010 16:34:01 +0000

About a month ago, I complained about Time Warner’s anemic upstream bandwidth cap on home cable modem service. (512k! Oh, the humanity!)

Well, a phone call to Time Warner and $10 a month later, my cap has been increased to 2 Mb. They call this their “Turbo” plan. (Turbo == fast, right?)

The asymmetry of my speedtest result below is still laughable, but the improvement in upstream AND downstream performance is very noticeable. Now my uploads to Flickr don’t completely saturate the connection and more than one person can actually use the network without hosing everyone else.

I still suspect that my upstream bandwidth puts a cap on the actual download performance I can achieve. I haven’t been able to find a rule of thumb to calculate how much upstream bandwidth is required to support a 20+ Mb/s download.

Surely there is a relationship between data coming down the pipe and the acknowledgements (or other handshaking packets) that are sent back?

Measuring network performance with iperf

Macro video of a hard drive in use

Jeff — Fri, 27 Aug 2010 21:13:07 +0000

2.5 Inch Hard Drive Macro HD Video from Brian Stuckey on Vimeo.

An exposed hard drive in operation. See more here:
Hard Drive In Use Video

Sadly, there is no sound, but the video is amazing. Check out Brian’s other videos on Vimeo or at his website ineedcaffeine.com.

The Tech Junkies Build a Wifi Radio (Video)

The ‘original’ oscilloscope Tetris

Jeff — Fri, 20 Aug 2010 16:24:40 +0000

One of my electronics labs in college had a few of these scopes (Agilent 54600B). I can’t remember who originally showed me how to access the game, but it was a great way to show off to the undergrads. You hold down two unlabeled buttons in the System/Utility menu and the game starts up.

Alas, I don’t think my DSO1014A has such a feature…

AVR HV Rescue Shield Code Update 1.2

Jeff — Wed, 18 Aug 2010 07:03:24 +0000

Version 1.2 of the Arduino sketch that powers the AVR HV Rescue Shield is now available for download.

The revised sketch now displays the target AVR’s existing fuse settings before asking you for new ones.

I also cleaned up and reworked the code in a couple places, but these changes shouldn’t affect the existing functionality.

If you have any issues or questions about the new code, post them in the support forum or contact me directly.

Measuring network performance with iperf

Jeff — Mon, 16 Aug 2010 16:41:15 +0000

My new place in Austin came with a huge perk for a tech geek like me – it came pre-wired for ethernet in every room. (Well, technically not every room is wired. The laundry room, bathrooms, and garage are not, an understandable oversight.)

After installing a new D-Link Gigabit Ethernet Switch, I wanted to check the throughput to see if I was actually getting gigabit speeds – particularly because the house is wired with CAT-5e cable (and not the recommended CAT-6).

There are many ways to measure network throughput. In the past I have usually copied a file across the network and used a stopwatch to get a relative sense of speed. However, due to file sharing protocol overhead I always got disappointing results and never knew maximum capability of my network.

This time, based on the advice of a more network-savvy friend, I decided to use a command-line tool called iperf.

iperf is a command-line tool to measure network performance. It is very powerful, but also easy to use for simple tests. For a more complete overview of what iperf is and what it can be used for, check out this tutorial or the iperf page on Wikipedia. iperf has a lot of options, and I won’t cover the majority of them here. For more usage information, consult the iperf manual.

If you run Debian or Ubuntu (Linux), iperf can be installed by executing

sudo apt-get install iperf

I did these tests with OS X on the Mac since both of my Macs have gigabit ethernet ports and my older PCs don’t. A package for iperf is conveniently available from Macports. It can be installed via the graphical package manager Porticus or opening a Terminal window and typing

sudo port install iperf

In my case, all I wanted was a quick test of TCP/IP network performance. This is easy to do, but it requires two computers, a client and a server, both connected to the network under test. Ideally, there should be no other network traffic during the test, as this will affect the results.

On the first computer, launch the iperf server by executing

iperf -s

You should see something like this:

------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------

On the 2nd computer (the client), open a Terminal window and run

iperf -c  -i 1

Within a few seconds, you should start to see reports coming in on both the client and server terminal windows:

------------------------------------------------------------
Client connecting to mini.home, TCP port 5001
TCP window size:   129 KByte (default)
------------------------------------------------------------
[  3] local 192.168.24.135 port 65142 connected with 192.168.24.77 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 1.0 sec    110 MBytes    924 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  1.0- 2.0 sec    101 MBytes    850 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  2.0- 3.0 sec    109 MBytes    914 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  3.0- 4.0 sec    100 MBytes    841 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  4.0- 5.0 sec    111 MBytes    927 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  5.0- 6.0 sec    102 MBytes    853 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  6.0- 7.0 sec    110 MBytes    923 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  7.0- 8.0 sec    102 MBytes    858 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  8.0- 9.0 sec  79.4 MBytes    666 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  9.0-10.0 sec  93.6 MBytes    785 Mbits/sec
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  1018 MBytes    854 Mbits/sec

The last report (for the interval 0.0-10.0 sec) is the average throughput for the entire test. I’m more than happy with 854 Mbits (927 Mbits/sec peak!) given my fairly long runs of CAT-5e cable and other machines using the network. Contrast this with my results over 802.11g wireless:

[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  24.9 MBytes  20.9 Mbits/sec

Ouch.

Bluetooth Headset inside a [toy] Handgun

Jeff — Tue, 03 Aug 2010 13:30:33 +0000

MayorMike, inspired by the article I wrote for Make vol. 20 (Retro Wireless Handset), stuck a bluetooth headset in a plastic toy gun to create his Handgun Bluetooth Earpiece Project. The best part – the earphone is located at the end of the barrel, so to answer a call, you stick it up to your ear. Genius.

The innards are shown below.

Nice work, MayorMike! May I suggest that you pair this with a Hand Grenade MP3 Player?

via BoingBoing

Getting settled in Austin

Jeff — Mon, 02 Aug 2010 18:39:49 +0000

We made it! Driving a moving truck almost 2000 miles across America was no picnic (it gets HOT in Arizona) but ~4 days of travel were relatively uneventful (only one flat tire!). Pretty much everything made it intact, including a few hundred pounds of lab benches and equipment. (Note to self, next time get twice as many moving pads as seems necessary!)

My wife and I have been getting acquainted with our new city. One of the interesting/unique things about Austin is the local trailer food scene. One example, shown below, is odd duck, where you can purchase local, sustainable, gourmet wood fired food out of a trailer in South Austin. Yum.

The biggest downside to Austin I have found so far (aside from the lack of In-n-Out and Trader Joe’s) has been the pitiful upstream bandwidth that Time Warner provides with their Roadrunner internet service. Check out these Speedtest results:

Holy asymmetric internet access, Batman!

Compare those results with this test I ran before I packed up my computer in San Francisco:

Over 4 megabits! If only I knew how lucky I was on Comcast when I could upload entire Flickr albums and HD videos in minutes!

Time Warner – 512K? Really?

Ok, that’s enough for now – time to unpack the power supplies and oscilloscope.

PS. I almost forgot. There are a few pictures of the move on Flickr.

MightyOhm is moving!

Jeff — Wed, 30 Jun 2010 19:20:32 +0000

I apologize for the slow updates as of late, but I have some big news that I would like to share with you:

MightyOhm is moving to Austin, Texas!

While the move should be pretty much transparent to anyone reading the blog, there will be a lot going on behind the scenes in the next few weeks. Most significantly, orders placed after July 9th will not be shipped before August 1st. The move will continue to take time away from the blog as I figure out how to move an electronics lab across three states. Don’t expect too many posts in the next few weeks!

I am sad to be leaving San Francisco (and the many friends I have made in this wonderful city), but I’m eager to explore a new city, meet new friends, and make Austin my home. Once I get settled, I would really like to meet some other electronics geeks in the area. If anyone who reads the blog lives in or near Austin, please send me an e-mail or comment below to say hello!

That reminds me: Does anyone know where to find surplus electronic parts in Austin? If you do, please post a comment here or add it to the wiki. As soon as I unpack, I’ll be looking for local substitutes for Silicon Valley’s HSC and Weird Stuff.

That’s all for now. Time to pack up my soldering iron and oscilloscope!

Austin Hackerspace Pics

Sale: 20% off AVR HV Rescue Shield

Jeff — Wed, 16 Jun 2010 15:49:39 +0000

Now through July 9th, order an AVR HV Rescue Shield kit and get 20% off!

AVR HV Rescue Shield Kit – $19.95

Maker Faire Retro Bluetooth Handset Talk on Ustream

Jeff — Thu, 03 Jun 2010 05:37:17 +0000

I didn’t know at the time that I was being recorded, but here’s a somewhat low quality video of the Retro Bluetooth Handset talk I gave on Sunday of the 2010 Bay Area Maker Faire.

The talk starts about 7 minutes into the video, so skip ahead unless you want to watch John Edgar Park of Make: television greet his fans.

Enjoy!

The Tech Junkies Build a Wifi Radio (Video)

Jeff — Wed, 26 May 2010 18:57:43 +0000

In this episode of The Tech Junkies, Ben and Eric show how to hack an Asus WL-520gu wireless router into a music playback device. By loading the OpenWRT firmware onto the router and adding a USB sound card, it is possible to convert this cheap/powerful router into a streaming box to be placed anywhere your WiFi is in range. Now you can build your own shoutcast/icecast receiver for cheap and get music wirelessly to any room in your home.

Pretty cool video based on my original Wifi Radio tutorial.

To leave comments or download the video, visit The Tech Junkies Episode #6.

Gary’s Wifi Radio Project

Maker Faire Bay Area 2010

Jeff — Tue, 11 May 2010 23:35:57 +0000

The Maker Faire Bay Area 2010 is less than two weeks away!

I’ll be giving two short talks about my Bluetooth Handset Hack over the weekend. Look for me on stage near the Make: booth.

I would love to meet some readers of the blog. If you spot me at the Faire, please say hello!

Update: I’ll be presenting on the Make: stage in Expo Hall at 12:30pm both days.

Maker Faire Retro Bluetooth Handset Talk on Ustream

Photo Tour of Sutro Tower

Jeff — Fri, 30 Apr 2010 03:30:41 +0000

David July, who runs sutrotower.org, posted a fascinating set of pictures documenting his tour of San Francisco’s Sutro Tower.

Sutro Tower Construction Updates, Photos, Links