Category: Technical Articles

November 28, 2011 / / Electronics
USB IR Toy v3

I got the USB IR Toy v3 as a free PCB from Dangerous Prototypes a few weeks back, but until recently I haven’t had much time to track down all the parts for it. Given that this is a v3 and not a v2, there isn’t a simple shopping cart of parts at Mouser kicking around. So, I decided to make one!

November 28, 2011 / / Electronics
The new copper tape in place

I’ve been getting great use out of my modded Evil Mad Scientist Laboratories Bulbdial clock (you might remember, I modded it with a touch sensitive strip to turn the display on and off), but it’s been having some problems lately. Because I couldn’t solder to the aluminum tape I previously used, the contacts taped in place were getting loose, causing the clock to flicker on and off. The loose contacts also made functionality very sporadic. The solution was to swap the aluminum strips out with the copper foil I bought a while back from Sparkfun for a whopping $3. 

November 20, 2011 / / Coding
STM32F4-Discovery

ST Micro in the last few weeks was the first to market with the brand new ARM Cortex-M4 32-bit microcontroller core. The really interesting new feature is the ‘F’ in the name – this is the first low-cost, low-ish-power light duty microcontroller to include a built in, single cycle per instruction 32-bit floating point unit. In typical ST fashion, the development board is awesome – it’s got a built in ST-LINK/V2 programmer and in-circuit debugger on the top half. The bottom half contains the M4 and a host of fun peripherals to play with, including a 3-axis MEMS accelerometer, an audio DAC with class D output driver, a bunch of LEDs, and all GPIOs broken out to .1″ headers.

August 18, 2010 / / Electronics

This may seem tirade-ish, and if so I’m sorry. This was spurred by the story posted here at TUAW. Basically, there’s a little USB pass through dongle that you can buy to eliminate your iPad “not charging” woes. TUAW kind of misses the boat on bothering to explain or understand it, so here’s how it works, in comment-on-the-article form (so read the article first):

August 14, 2010 / / Electronics
front view
My custom board

A few people asked about this. I’ve seen breadboards with binding posts before, but usually they’re nothing special, just some banana plugs near the board that you can screw a jumper wire into. I wanted something a little more full featured, so I whipped this up.

August 13, 2010 / / Electronics
Bulbdial clock with breadboard and multimeter
Let’s make it touch sensitive!

UPDATE: People keep asking about the breadboard setup. Fair enough. I’ll throw together a quick overview when I get home today.
UPDATE: here it is: http://www.alexwhittemore.com/?p=462

The Bulbdial clock from Evil Mad Scientist is probably the coolest clock idea I’ve ever seen. Even cooler are my parents, who got the kit for my birthday.  The basic idea is that three rings of LEDs cast shadows onto a clock face to form H/M/S hands, somewhat like a sundial, with the hands slowly animating around. A lot of thought clearly went into making this kit, and it’s very nicely done, but there’s a major drawback: I want to use it on my bed side table, where I usually keep a clock, but it’s too bright for me to fall asleep! Of course, that’s been thought of too: in the normal view mode, the three buttons at the bottom of the clock are brightness up, down, and “mute,” which turns off the LEDs entirely. But they’re hard to get to buried underneath the frame of the clock, and it makes muting the display cumbersome in the dark. Let’s fix that!

August 11, 2010 / / Electronics
Crappy Buds
Crappy Buds

Say what you will, but iPhones are pretty awesome, and so are the headsets that come with them. At least up until you put them in your ears. The inline controls are awesome, but the speakers are uncomfortable, lacking in low end punch, and do nothing for sound isolation. Other, much better headphones exist, but for under a gajillion dollars, none come with the same kind of inline controls. Here’s how to have the best of both worlds.

August 7, 2010 / / Coding
August 5, 2010 / / Coding
Jailbreak Development for iOS4!

Vital Stats:
iOS 4.0.1
Xcode 3.2.3
Mac OSX 10.6.4 Snow Leopard
iPhones 3G, 3GS, 4 (I finally have the whole lineup!)

PROBLEM: I still can’t get iPhone 4 working. If you have one, please try it and help me out! UPDATE: Found the cause of the problem to be certain status bar libraries installed alongside other apps. I’m not sure why they cause the problem, but see full notes at the bottom of the post.

The Goal: As usual, we want to be able to click “build and go” in Xcode and get the app we’re working on to load to the phone and start up. Also, we want to be able to debug from within Xcode itself. After all, Xcode is cool, and terminal+makefiles+gcc+gdb is lame.

August 2, 2010 / / Electronics
LaunchPad
Meet the LaunchPad

I’ve been playing with the TI LaunchPad the last day or two since I’ve been home in the US. I ordered two when they launched, but I was abroad and only just started playing with them, and I have some first impressions to share.