Planes on a Snake

Posted on January 31, 2012 by joat

This past weekend was the 4th annual Global Game Jam, and we hosted a site in the triangle again. I was an organizer this year, but I still had plenty of time to jam, creating Planes on a Snake with my team. The theme was a picture of an ouroboros, which we interpreted by setting a shmup on the back of the world serpent.

Brief Play Description

A rift in spacetime has resulted in a large number of World War II era planes getting stuck on the world snake.
Join the frequent fliers club of Ouroboros Airlines, racking up points while taking advantage of the torus nature of your new environment.


(video contains some strong language)

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Speeding up LPD8806 show() without hardware SPI

Posted on January 17, 2012 by joat

If you’re using LPD8806 LED strips and you can’t use the hardware SPI port (e.g., when using an Ethernet board), there are two other options in the Adafruit library: the default mode and ‘slowmo’ mode. The default mode is decent, but the flexibility of being able to choose the pins at runtime comes with a cost.

However, you can still get a decent speedup by defining your pin usage at compile time in a replacement show() function. I measured the time required to update an 86 LED strip using each method on an EtherTen board (Atmega328 @ 16 MHz, same as the Uno):

30.23 ms - Adafruit 'slowmo' method (digitalWrite)
7.76 ms - Adafruit default method (port pointers)
1.54 ms - Compile-time method
1.43 ms - Adafruit hardware SPI method

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Reducing code size on Arduino Ethernet boards

Posted on January 16, 2012 by joat

The Ethernet library grew in size several KB from 0022 to 1.0, which is a big deal when you only have 32 KB to play with. You can save about 2 KB by compiling out DNS support:

Wrap the following pieces of code in #if WITH_DNS

  • Dns.cpp and Dns.h:
    The entire file
  • EthernetClient.h and EthernetClient.cpp:
    int connect(const char* host, uint16_t port)
  • EthernetUDP.h and EthernetUDP.cpp:
    int beginPacket(const char *host, uint16_t port)
  • Client.h:
    virtual int connect(const char *host, uint16_t port)
  • Udp.h:
    virtual int beginPacket(const char *host, uint16_t port)

Add #include "EthernetUDP.h" to EthernetUDP.cpp, since it’s currently relying on the indirect include from Dns.h.

Posted in Arduino, Electronics | Tagged , , , | 2 Comments

Faster Arduino development

Posted on January 16, 2012 by joat

I’ve been using Arduino boards for a bunch of random projects lately. They may not be as inexpensive or as small as throwing together a microcontroller and a resonator on a piece of perf board, but they’re a lot faster when making one-offs: lots of shields with ready-to-go libraries, quick programming / test cycle, etc…

One major downside is that the official Arduino IDE has a super-awful text editor, but there is a solution. Visual Micro has a plugin called Arduino for Visual Studio that makes everything ‘just work’ in the VS IDE, even VAX. Install the Arduino 1.0 IDE, then install the plugin, and all you have to do is point the plugin to your Arduino directory the next time you run devenv. It handles the rest, setting up syntax highlighting for .ino/.pde files, adds a toolbar to pick the board type and COM port, etc… To top it all off, it compiles about 10 times faster than the official IDE (0.2 – 0.5 s versus 5-10s); so much faster that it seems like there is a bug in the current version of the Arduino IDE.

Long story short, if you are doing any Arduino development and have VS 2008 or VS 2010 (the express edition won’t work since it doesn’t have support for plugins), you should download it now for a massive productivity boost.

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Return of the fooding

Posted on January 16, 2012 by joat

Weekly fooding has finally started back up.

The evening had some new converts to green beans almondine, and the spiral baked ham turned out very nice. I followed a recipe from Emeril Lagasse, making a cherry-orange glaze, and cooking with Coca Cola in the pan to prevent the ham drying out.

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Global Game Jam 2012

Posted on January 5, 2012 by joat

I’m happy to announce that we will be hosting a Global Game Jam site in the NC Triangle area again this year, January 27th to the 29th at Joystick Labs in downtown Durham. Sign up now at http://globalgamejam.org/sites/2012/triangle-game-jam.

More information will follow shortly, but the format will likely be very similar to past years:

  • Getting started around 6:00 PM on Friday, announcing the theme, brainstorming ideas, and forming teams, etc…
  • Full day of work on Saturday
  • Finishing up on Sunday by 3:00 PM, showing off the games to each other afterwards.

This is the 4th year of the Global Game Jam; to get a better idea of some of the cool things possible in a weekend, check out some of the games made in the triangle area in past years:

Cross-posted from the Triangle Game Jam site

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Christmas gifts: Candles

Posted on December 19, 2011 by joat

One of the things I made for Christmas gifts this year were candles. In addition to the typical cylinder and square candles, I made some candles in the form of the Gears omen and a lime.

Making candles with a homemade mold

For my first time making molds, and first time pouring candles, I’m really happy with how things came out.

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CNC machined Scrabble board

Posted on December 4, 2011 by joat

A neat little Scrabble board that I made and took on my vacation trip:

Custom travel Scrabble board

A word to the wise: orange and red Sharpies are nearly indistinguishable from each other on a frosted plexiglass medium.

Posted in Projects, Travel | 1 Comment

Robotender Mk3

Posted on October 30, 2011 by joat

Finished Robotender Mk3 just in time for my halloween party (with literally minutes to spare). This one is a pretty radical departure from the previous designs, using a robotic arm instead of pressurized dispensing. I managed to pick up a Scorbot ER-III arm and controller off of eBay. They were originally used for teaching robotics and motion planning at universities, and are generally pretty used-and-abused (two motors were almost falling out of their mounts on this one), but it runs quite nicely after everything was cleaned and tightened up.

Robotender Mk3, wide view

It’s a little slow compared to the Mk1, but it’s a lot of fun to watch, can hold more bottles, and is easier to maintain. It uses custom bottle carriers that hold 710 mL soda bottles, and can hold up to 24 such bottles. There is a digital scale hooked up to the computer as well, which gets zeroed once a bottle reaches the pour site, letting it determine how much liquid has been poured much more accurately than the simple time-based approach used in Mk1.

Pouring an ingredient

I took a number of pictures during construction on this one, so I may do a build log post later.

Next steps:

  • I’m going to look into building a new motor controller for it, so I can get better feedback and drive it faster while still keeping a solid grip on bottles (can’t currently ignore the gripper stall state for fear of missing any other motor stalls, meaning I have to do a slow 1/10th speed backout on the gripper to get the max grab force I can).
  • The bottle holders are on their 6th iteration already, but positive grip is still a bit of a problem, so I’m probably going to redesign the bottle holders with a triangular slot and make some triangular nylon plates for the gripper. This might also allow me to be a little less precise in the back-off, and speed it up without a new motor controller.
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Infected Omen Light Box

Posted on September 20, 2011 by joat

I pulled an all-nighter and designed/fabricated a LED edge lighting box plus etched plate in advance of the Gears 3 launch. The original plan was to slide an unused junk android tablet in and show some numbers from the stats dashboard in that central window, but I wasn’t able to get the tablet on the secure network at work, so now it’s just a pretty light box sitting on my desk. I almost slid my iPad in, but the slot I machined for the tablet is about 0.5 in too short for an iPad, though it had 0.75 in of slack for the target tablet.

The light gently pulsates / undulates around the border (driven by an Arduino), aiming to look a bit like the corrupted omen on the title screen.

The LED strip I used are LPD8806 driven strips from Adafruit, and they are a dream to use compared to the older Christmas light strand style strips I’ve used in the past. Each LED is individually addressable via a SPI-like interface to set a 21 bpp RGB color, and they have their own internal PWM clock, so you can fire and forget, no need to keep clocking them.

Also, Gears of War 3 is out, you should play it!

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