obligatory obscure reference

… because I’m currently doing a lot of hacking to try and finish up my first-semester project in the mTID program at CMU. I have a backlog of half-finished posts that will get finished after the semester is over.

Technorati Tags: design, mtid, school

I wish this were in The Onion and not the Pittsburgh Post-Gazette:

A national children’s advocacy group is pushing to get Pittsburgh removed from the Street View of Google’s map search until the technology is refined so pedophiles can’t use it to pinpoint children’s homes, schools and playgrounds.

Street View, an addition to Google Maps that uses vehicle cameras to take 360-degree, street-level views of neighborhoods, allows users to virtually cruise down a street and across a city. In the process, the tool shows pictures of children, toys and family cars that could tip a would-be predator to an area where children could be found and potentially victimized, according to the group, Stop Internet Predators.
[...]

OMFG! I bet you could use Street View to find cars to steal! Or burglars could find houses with plate glass front windows surrounded by bushes that are easy to break into! Rapists could find bushes to hide in!

I mean, it’s not like people can drive around neighborhoods and find those things in real time, is it?

Sadly, this ignorance about crime is nothing new.

Quintilian, INSTITUTIO ORATORIA, II, xvi (first century AD):

“Doctors have been caught using poisons, and those who falsely assume the
name of philosopher have occasionally been detected in the gravest crimes.
Let us give up eating, it often makes us ill; let us never go inside
houses, for sometimes they collapse on their occupants; let never a sword
be forged for a soldier, since it might be used by a robber.”

Technorati Tags: google, idiocy, privacy

After ~5 minutes looking on the interwebs, I gave up and just made my own EAGLE library file for the Arduino Nano. I haven’t used it to make a board yet, so I’m going to call this the “alpha” version until I do. Use as you like, just don’t blame me if it’s broken.

jet’s EAGLE lib o’ doom

Technorati Tags: Arduino, EAGLE, pcb

Ok, first cut at a spreadsheet comparing Arduino types. I still need to add the LEDuino and probably some new columns, so consider this an alpha at best.

CSV, PDF, and Excel(-ish) formats.

Technorati Tags: arduino

As part of figuring out which Arduino to use, I’m making a chart of the various characteristics of Arduino boards.

So far I have the obvious — # I/O pins, form factor, required power, etc. Anything in particular that you (collective) would find useful in such a chart that I might not think of? For example, do you care about weight? Physical dimensions without pins?

Let me know in email or in comments.

Technorati Tags: Arduino, survey

I’ve had a HP Business Inkjet 1200n for 4-5 years now and it’s been a great printer. For only $250 I got duplex, ethernet, color and dual trays.

Apple’s OSX, however has not played well with it. Starting with 10.4, there’s been a low-level problem in CUPS (the free software Apple uses for printing and has since “bought”) on OSX/Intel that I’ve never been able to diagnose and Apple hasn’t cared to fix it either. So, to print from our MacBooks we’ve had to use a G5 as a print server. Not the end of the world, but annoying.

I finally upgraded everything to 10.5. and whammo, I can no longer print from the G5. After a few hours of mucking around, I discovered what you could either call the “right way” or a “workaround”. It’s certainly not something you’d think to try, but it works for me:

1. Go into Printer and Fax preferences and delete any existing HP printer using the “-” button.
2. Start adding a printer using the “+” button.
3. Pick “More Printers” and wait for it to grind.
4. Pick “HP IP Printing” from the scoll bar.
5. Pick “Manual”
6. Enter the printer’s IP address and click “Add”.

That should bring up a dialog correctly identifying your HP printer.

Technorati Tags: HP Business Inkjet 1200, OSX, printer

Wondering if this has happened to anyone else….

I applied the most recent Apple Security Update on a PowerBook G4 15″, and after reboot, there’s a pixel-wide vertical stripe on the display. I’ve tried resetting the PRAM, rebooting, booting from install discs, booting into 9.2, letting it cool off, etc. Nothing has made it go away.

I guess it could be a coincidence, but someone else had the same thing happen and posted about it on the Apple discussion forum. I can understand a software upgrade triggering a disk failure by trying to use parts of a hard drive that are damaged, but how could it manage to trash a graphics adapter or display?

Technorati Tags: powerbook, security update, vertical stripe

Ok, this was stupid fun and really easy. I’m relearning the Morse code — I originally learned it using the excellent ARRL CDs. As part of re-learning it, I thought it would be fun to see if I could learn it visually as well, by looking at a blinking LED. It kinda makes my brain hurt, but it actually might be doable.

So here it is, my simple Morse Code arduino sketch.

I think I might try parsing Morse next, it’s a much more interesting problem…

Technorati Tags: arduino, morse

Ok, this was a bit more fun and geeky. The SHT15 is a temperature/humidity sensor made by Sensirion. I bought mine from Sparkfun, and at $42 it’s a bit pricey, but it’s pre-mounted on a breakout board saving me a nasty soldering job.

The SHT15 isn’t as fragile as a lot of other electrical components — you can get it wet, put it in the sun, etc. I’ll probably just mount it at the end of some very long leads and not bother putting any sort of protective case on it.

Being the rocket scientist that I am, I didn’t download the specs until I decided to actually write code. Turns out that the SHT15 uses a serial protocol developed by Sensirion; but they were kind enough to post some sample code for the 8051 so it wasn’t too hard to get working on the Arduino.

If you’re trying to get this working, take a look at my Arduino sketch. Writing code to read serial protocols using clock and data pins isn’t for the newcomer, but it isn’t terribly difficult if you know a bit of C, bit-wise operations, and have sample code to reference along with the timing diagrams.

Technorati Tags: arduino, hacking, sht15

Reading the ADXL 3xx is pretty straightforward — give it power, run lines from the x,y,z pins to three analog pins, and do analogRead()s on the pins.

What’s a bit trickier is dealing with the sensor values. Resting flat on my desk, the x, y, and z values all vary on each read. It’s only by one or two steps, but it’s still noisy and could introduce a lot of jitter into your code. One way of eliminating/reducing noise is to take a running average of sensor readings, then use those to make your decisions.

Here’s an example Arduino sketch that reads the sensors, computes a running average, then displays the previous average, average, and current raw value for each axis.

A couple of related notes:

• The power you give the ADXL needs to be the same as the reference voltage on your Arduino. If you power the ADXL directly from the Arduino, then everything is fine. If you power it from another source, you might need to use the external power reference features on the Arduino.
• While you put power to the ST pin, the ADXL will force all three outputs to the middle value. This is useful for calibrating the ADXL by reading what it things its middle values are for each axis. However, it’s not something the average person will probably care much about, I find it useful as a “is it really working” test while I’m debugging a circuit.

Technorati Tags: adxl, arduino