HD44780 Instruction Set

There are a lot of LCD modules that use the HD44780 controller. This is a chip that accepts parallel data (8 bits) to control an LCD character display. In my recent twitter2LCD project I needed to determine some of the control instructions such as how to make text scroll and how to control the position of the cursor. There are quite a few places where the complete instruction set is posted, but they are geared more toward seasoned digital electronics users. The main insight I can offer is that if you are using a serial-enabled LCD (as I was), you have to convert the 8 control bits into a byte and send that byte after a specific control character. For the Sparkfun LCD-09393 and related SerLCD modules, the control byte is “0xFE.” This byte grabs the attention of the onboard controller and tells it that the following byte is an instruction and not a character.

Zotero Review

I’ve been a big fan of bibliography software and I’ve written before about how much I like BibDesk for this role. That said, my workflow just wasn’t complete until I gave Zotero another try recently. The software has come a long way since I first looked at it, and now I am happy to say that it is my primary tool for tracking resources while I’m searching through articles. Two features finally sold me on zotero: the meta-data is scraped correctly (identified and stored) from the web resource in all of the journals I have tried, and I can easily sync my library and my stored PDF files between multiple computers. File sync is free through zotero.org (up to 100 MB) but I have a WebDAV server at work so I use that for unlimited storage. As a major bonus, I also like the feature that will automatically download and link the full-text PDF file (if you have access to it). These three things combine to make a great tool.

Twitter to LCD – with scrolling text

I’ve been having some fun with a Sparkfun Serial-enabled LCD screen (LCD-09393, $24.95). This little package will write out whatever you send along a serial data line. So this means you can add an LCD to a project with only three wires:  +V, GND, and RX (serial receive). In the real world, I’m hoping to use these LCDs in some lab instruments that we’ll be building in the spring semester. In particular, I’m looking at an arduino-based frequency counter. I also want to explore an arduino-based PID controller for various lab projects (temp. control, etc.).

My first test, however, was just getting the LCD to work. And then, I wanted to make it show my Twitter status. I’ve been using twitter (DrDawes) to post my office status and give students updates as to where I am or when I may be around again. This has been helpful since my research lab is in another building and I tend to be available but it may not look like it since I’m not in the physics building. This way if I want to step over to the lab, I can simply send an update, and save people the trouble of tracking me down. The rub is that not everyone has twitter, and sometimes people just come to my office anyway. That said, my goal is to post a 16×2 LCD screen on my door so that my availability status (formerly written on a whiteboard, or post-it) can be more 21st century.

Nice Octave Plots

One thing I look for in a numerical package is the ability to make nice plots (typically PDF) of what I’m working on. I know I could almost always work on my data, export it, and make a great graph… but in keeping with the 80/20 rule I want to be able to do most of my plots without a lot of extra work. This is especially true if I’m making a one-off plot for class notes. For publications, I’d be happy to hand draw the figure in blood while standing on my head if I had to. The bottom line is: it’s 2009, making a nice looking PDF plot should be easy.

Here is an example along with some quick tips I’ve found along the way. Hopefully these are easier to find for you than they were for me (digging through docs and searching through listservs). Remember, Octave is scriptable so you can save this in a plot template or a function, and make your plots even easier.

Build a Laser Tripwire

Courtesy of fatllama@Flickr

I gave my final in Electronics on Tuesday (Dec. 15), and it went so well,  I can’t stop thinking about it. The format was something I haven’t tried before: 1.5 hours of written test (individual) and 1 hour of group problem solving. The problem they had to solve was to construct a laser tripwire alarm.

There are seven students in the class, so putting them all in one big group is feasible, but I was worried about students not participating or being pushed out of the project by other students. It turns out that I had nothing to worry about, they delegated and divided perfectly, coming back together to get over some hurdles and then breaking apart again to complete their roles. They passed with 12 minutes to spare, and even left it set up as a demo at their project showcase party. My only hope is that future classes work together as well as this group did.

LDAP search of Active Directory

Our campus operates an MS Exchange server so there is a university-wide address book hosted for all to use. As a mac/linux/unix user, this is sub-optimal for me, but I know I have the tools to work around it. The challenge is matching command-line options with the server’s expectations. This probably won’t work for you verbatim, but if you find yourself in a similar situation, it may get you closer to something that works. I’m happy to try to help if you post a comment or question.

Exchange LDAP in Thunderbird

I have struggled for a while to use our campus resources from my mac(s) at home and at work. In particular, I haven’t had much luck getting any email program to successfully auto-complete email addresses using LDAP. To clarify, the campus has an exchange server that is running Exchange 2007 (as near as I can tell). I know the server name, port, and have determined some other bits from various posts elsewhere. The single biggest issue is that the LDAP server has an expired certificate, so that was the final roadblock that I recently overcame.

Physics Education Resources

It has been a while since my last list post, and I feel like focusing more on my mission for this blog. With this in mind, I would like to share a list of my favorite resources for physics teaching and physics education research (PER). Hopefully some of these are familiar, and if you use others, let me know in the comments section.

• MIT Open Courseware
  • A growing collection of course materials from MIT. I find these to be most useful as a reference to see what other students are seeing in Physics. There can be a lot of flexibility in a curriculum and as a young professor, I like to see what other people are doing in their courses. There are a lot of reasons that I can’t use these courses verbatim, but it’s nice to see what is happening at a leading institution.
• Concept Tests (PER@C)
  • One of the easiest things you can do for your course in Physics is to check student conceptual understanding. It is most insightful to pre- and post-test and it’s important not to use these as for-credit exams. This is a test of your abilities as a teacher more than a test of your students… the sooner you come to terms with this idea the better.
• NCSU Concept Test links
  • Another list of concept tests for a wide variety of courses.
• PhET Java-based Concept Simulations
  • Ever thought there had to be a better way to teach a new concept? Sometimes all it takes is a good simulation and giving students a chance to tinker around with some different scenarios. Many of the PhET sims are designed to help students build intuition as a preparation to a more thorough understanding.
• PER Central
  • A general resource for Physics Education Research.

I’m sure there are many other good sites, but these are the ones I end up referring to quite a bit. In the future, I will discuss these topics in other posts, so feel free to contact me with any questions about how I’ve used these resources.

Octave on Mac

GNU Octave

I have been interested in GNU Octave for a while, although never bothered to play much since I had access to recent Matlab releases while I was at Duke. Now that I am managing my own software budget, and trying to keep it to $0, I have a new found appreciation for Open Source Software. Of course, I like regular free-as-in-beer software too, but I’ve always preferred to use work that is licensed in an open way.

For anyone else who has been hesitant, Octave is now mature enough to be a Matlab replacement. You may even be impressed to find comparable toolboxes… also for free (as in speech and beer). I want to get to know Octave enough to use it in the classroom. At Pacific, we use Maple a fair bit and in the introductory courses, Excel is a stand-by for quick one-off data plots. Both of these tools are well suited to some tasks, but lack some of the features that a package like Octave offers. One definite advantage to Octave in the classroom: students who learn Octave will effectively know Matlab and can add that to their resume.

Sustainable Electronics

photo credits: ladyada @flickr

This fall Physics 364 (Electronics) will have a project component. Pacific has chosen Sustainability as a campus-wide theme for this academic year, and with this in mind, I will encourage the class to consider projects that explore the application of technology (electronics, physical computing, etc.) to improving sustainability. This can be challenging as technology is often viewed as a culprit in the current global crisis. One major challenge for the project, is to transcend this view and demonstrate ways technology can help us in a global sense.