Saturday, June 4, 2011

Programmers Anonymous notes, 1000

 "While other visitors gazed at the workings of the beautiful instrument with the sort of expression, and I dare say the sort of feeling, that some savages are said to have shown on first seeing a looking-glass or hearing a gun - if indeed, they had a strong an idea of its marvelousness - Miss Byron, young as she was, understood its working, and saw the great beauty of the invention.Augustus De Morgan commenting on Ada Lovelace (then Miss Byron) on the occasion of Ada's first introduction to Charles Babbage's difference engine, on June 5, 1833. (from Lovelace met Babbage on this day 1833)

Tiny blinking lights:

We wrote, installed and tested a program that controls an embedded processor (an Arduino Mega 2560), a general purpose computer on a chip. The program caused the device to signal "Hello world!" in a way I understand; tiny blinking lights. A brilliant twinkling, because if you can blink some lights any way you want, just about anything can be controlled.

Far more sophisticated computers are now common -- for example any cell phone. But this one is designed to be inexpensive, easy to program, open source with open hardware design, and has flexible I/O with external digital or analog electronic devices. This particular microcontoller is also hooked up to a physical interface (hardware parts) and firmware designed for serial communication with Android controlled devices. It is suitable for use as the executive control system of a robot brain. The whole package is a beta version of the Android Open Accessory Development Kit (ADK) (also see Why Google Choosing Arduino Matters and is This the End of “Made for iPod” (TM)?).

An ADK Arduino device might be called an "Android accessory", because it can be controlled by an Android device (like a smart-phone running an Android operating system). Here is a short video of the DemoKit Android application showing bi-directional communication between a handheld Android device and an ADK device. 

But because the ADK device is configured as a USB host controller, it is the Arduino that controls the Android device. So an Android device is actually an accessory to the ADK device.

This example doesn't communicate with Android at all, running alone on the ADK Arduino device.

Here's the ADK device's top side (left), the device with a red and blue light blinking, and the device swept across the camera frame to show that the lights are on for brief periods and with changing relative color (each circle is illuminated by two LEDs, red and blue):

Blinking lights are a central element of physics (a photon is the smallest and briefest blinking light) and a wide range of technologies (for example telecommunication and video monitors). They happen to be close to my heart and work. I've spent a lot of time in the last decade blinking lights in front of people and seeing how their brains blink back. Conceptually everything from motors, to packets, to robots, to the nervous system of animals is composed of, among other things, tiny blinking lights.

Anyone is welcome to borrow this kit for tinkering. The Arduino part is cheap, available, and all that is required, except for extra LEDs, motors, etc.. If you make a robot for me I'll buy you an extra microcontroller and board in exchange.

Did I mention that the hardware and firmware is open source? While this kit, designed and commissioned by Google, is expensive and not currently available, anyone is free to make compatible devices. And they already have. For example, Seeeduino ADK Provides Inexpensive Android Open Accessory Kit Alternative for $80.

Collatz conjecture proven?:

A while back (see Collatz conjecture and binary palindromes) we looked at patterns in the 3n + 1 problem. A while back Paul Erdős famously said of the Collatz conjecture that "Mathematics is not yet ready for such problems". Now Gerhard Opfer, a (former) student of Lothar Collatz, has submitted a paper purporting to prove the conjecture. I don't understand the methods or the proof, and it hasn't been peer reviewed yet. Here's a brief news item about the result, "Deceptive puzzle may be solved after 74 years". 

Sissy's Magical Ponycorn Adventure

Spherical cat in space (or Lady's lunar emulation):

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