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Big Data Science Professional

7/31/2015

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I recently finished the first two modules of Arcitura's Big Data School. Consequently, I am now certified as a big data professional. Yay me!

The first two modules cover the definition and scope big data and big data systems architecture at a high-level and in a platform-agnostic way. I appreciate the platform agnosticism. The modules take a few hours to go through before being ready for the exam. I found that if I read through the workbook twice, I was more than adequately prepared for the exam and was able to pass them both with honors. Also, the included CDs seem pretty useless unless you are a particularly aural learner. I found the tone of the speaker to be dull and uninteresting. The books that come with the modules seem interesting -- I only read half of the first one and haven't started the second one. They are not necessary for the exam however.

I plan to continue with modules 4-6 until I earn my Big Data Scientist certification. 
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Think Stats

2/27/2014

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Last week, I finished plowing through Allen Downey's Think Stats. It took me about 5 days to work through it cover-to-cover. This book is great for those who need a crash course in using Python to do statistics. The conceit of the book is that it's a stats book for programmers. Hence, the statistics in it aren't past an upper-lever undergraduate level in difficulty. However, the programming required to work through the problems is at a higher level than I have seen in any other introductory stats book. I found it to be a great way to improve my Python programming. I worked through about 80% of the examples, skipping only those that were either trivial or did not seem relevant to my learning goals. For many of the examples, Downey provides .py files you can download from the book's website. I found that I usually took a different approach to solving problems than he did, but we most often agreed on the solutions. 

Anyway, the book is available as a free download and worth the time.

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MUX Chips Are All Wired Up

11/26/2013

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This is a bit of a mess, but itThe next step is to connect it all to the Arduino and start tweaking the program to work interface with the chess engine.
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Wires wires everywhere and not a drop to drink

11/20/2013

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After about 18 hours of drilling, soldering, and gluing, I have completed the majority of the wiring for the chess board. There are 64 Hall sensors, one for each chess square. Thankfully the Hall sensors can share a common power and ground, which reduces the number of wires. After testing each individual sensor, I liberally smothered the solder points in hot glue to prevent jostling from causing anything to break loose.


The next step is to wire up the multiplexing chips and figure out how to turn the sensing into chess moves. I'm not looking forward to wiring up all the multiplexers. Thankfully, I have the 3rd season of Walking Dead on Netflix to keep me company.
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A LEGO Trebuchet

11/11/2013

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Devin and I made a LEGO trebuchet for his monthly science project. I thought I'd share. The two videos show the first and second incarnation of the trebuchet as explained by Devin. In the second incarnation, we put a hinge on the counterweight and properly attached the sling. 
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How I spent my Friday night

11/8/2013

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Tonight I installed the hall sensors to the underboard for my robotic chess board and began wiring. I ran the ground wires and soldered all the resistors between the Vcc and the output pins on the hall sensors. Good thing there were some people around HackPittsburgh to keep my company. Enjoy the pictures. 
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Driving Many Hall Sensors with a Multiplexer

11/7/2013

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I wanted to post a quick update about the chessboard. I have tested using several Hall sensors simultaneously using a multiplexer (MUX). The multiplexing chip I chose allows for the controlling of 16 sensors while using only 7 pins on the Arduino. Since there are 64 squares on a chessboard, I will need 4 MUX chips. Adding additional chips only requires 5 additional pins per MUX, bringing the grand total to 22 pins, 20 of which needs to need to be I/O. This is approaching the number of pins on my Arduino UNO and I still have to drive three motors to move the chess pieces. I have two simple options at this point, buy an Arduino Mega, which has a near infinite number of pins (54 digital I/O and 16 analog inputs) compared to the UNO (14 I/O, 6 analog), or I can use a fifth MUX to offload some of the pins. Thankfully, the MUX chips I bought are I/O and therefore will allow me to switch through the 16 pins on each of the other 4 chips. Since I already have 5 MUX chips and I don't want to spend the $60 on the Mega, I'll give this a try first. I might try offloading the sensor work to the Raspberry Pi and use the Arduino for only motor control in the end. I haven't tried using sensors with the Pi yet so I don't know how well that will work. Anyway, I made a little video where I'm driving four Hall sensors with the Arduino through a MUX. Everything seems to be working fine. I didn't do all 16 because it would have been a wiring mess on the tiny breadboard and the sensors would be close enough to for multiple to be tripped a once when the magnet is near by. On the chessboard, they will be far enough to avoid magnetic bleeding (a term that might not describe what I mean, but I like it enough to keep it) away and there will be more space to wire everything correctly. The next step is to start wiring together the sensor array, which I will work on this weekend. 
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Quick Chessboard Update

10/30/2013

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I took a little hiatus on the robotic chessboard project I have been working on to better plan out some of my methods. I decided that the sensing of the position of the chess pieces will be done by Hall sensors. I will place a Hall sensor under each square of the board. The kind I bought are essentially switches which turn when one polarity is brought towards the sensor and turns off at the presence of the other magnetic pole. I put small magnets in the bottom of each chess piece. In the first video, you can see that the chess piece activates the hall sensor, which lights the LED. I then use the opposite pole of the magnet, which I glued to a stick, to reset the sensor. (Sorry for the vertical nature of the video. One of these days, I'll remember to consistently hold the phone sideways when recording.)
For the operation of the robotic chessboard, these latching Hall sensors pose a problem. As shown in the above video, the sensors would not turn off when the pieces are removed. Hall sensors that do not latch are nearly twice as expensive at the latching kind. This adds up when 64 are needed. I solve this problem by using a digital pin on the Arduino to control the power input to the Hall sensor instead of the 5V pin. This idea comes from the comments on Sparkfun. As you can see in the second video, the sensor now detects the presence of a magnet.
The next step is learning how to control 64 inputs on the arduino with a mux chip, which allows for control of 16 hall sensors using only 4 pins on the arduino. The next update will hopefully show a full chess board which detects where the pieces are or at least progress in that direction.
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Devin Finished His Lightsaber

10/12/2013

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It turned our really well. He decided to sand the plastic tube at the end and we put some plastic wrap at the far end to catch and diffuse some of the light there. It turned out better than the one I covered in tissue paper. Perhaps I'll redo that one when the 5 year old breaks the tube off. It's only a matter of time. Here are some pictures of the finished lightsabers. 
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A Finished Lightsaber

10/9/2013

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Tonight I went to the hardware store and bought some l-brackets to attached the tube to the base of the lightsaber. The tube is made out of a plastic florescent light cover. Then, I stuffed some tissued paper in the far end and put some plastic wrap over the end. After that, I wrapped the tube in tissue paper. I have included pictures of various steps and the finished product. I also put a 9V holder in the bottom to stop it from rattling around.

I'm trying to keep my 5 year old's hands off it until Halloween because the tube is fragile and he wants to use it for his costume. We'll see how long that lasts. Devin doesn't like the look of the tissue paper so we're going to try something else with his. He's going to take some fine sandpaper to the tube to turn in cloudy and put some aluminum foil over the far end to reflect some of the light back. If that works, maybe I'll redo this lightsaber in the same way. I don't really like the wad of tissue I have glowing at the end.

Anyway, this project has been pretty fun and very simple. I'm really happy with out the handles turned out .
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