Demystifying PID Control With A Look At The New Arduino PID Library

July 21, 2011 by Mike Szczys 18 Comments

We’ve been hiding away in air-conditioned comfort to wait out the hot weather afflicting most of the US right now. Luckily we’re keeping busy with the great links coming into our tips box.

[Brett] sent us a note about his work on the new Arduino PID library. He is the author of the original library and recently decided it was time for a ground-up rewrite. But along the way he took the time to explain PID control and the choices he made during development.

We see a lot of PID controllers around here, like this router based espresso machine add-on. Proportional-Integral-Derivative Controllers are a way to make sure the control you intended to get from your devices is actually achieved in practice. They monitor a process and accumulate results over time in order to account for future events. From what we’ve just described you can see why the subject needs to be demystified.

Get yourself elbow-deep into [Brett’s] article. He does a great job of discussing each issue, and uses a multitude of easily understandable graphs to show the hurdles each portion of code is meant to overcome.

Controlling An Infuriating Game With An Accelerometer

July 21, 2011 by Brian Benchoff 7 Comments

[Daniel] just made a motion controlled game controller to go with his infuriating game. Thankfully, [Daniel] posted the source for this game so first time players already know the level select codes.

The controller is based on an Arduino Uno with what looks to be a Sparkfun 2-axis accelerometer providing the tilt sensing. A similarly sourced half-inch force sensitive resistor and temperature sensor control the ‘jump pads’ in the game. A small vibrating pager motor strapped onto the controller as a rumble pack.

Continue reading “Controlling An Infuriating Game With An Accelerometer” →

Klout Klok Tracks Your Popularity, Time

July 21, 2011 by Brian Benchoff 7 Comments

[Fabien Royer] has been playing around with Netduinos and he just came up with a really awesome project that will display the time and social media popularity. It’s a very nice build, and we’d guess that his social media influence is going to go up very shortly.

Klout is a service that connects to your Facebook or Twitter profile and tells you how much influence you have on a scale of ~~1 to 100~~ (possibly 10 to 100. see this). To build the Klout Klock [Fabian] used a Netduino Plus, a good choice because of the integrated ethernet port. The Netduino connects to the Klout API to either satiate vanity or admit prestige. The display is an adafruit TFT screen.

Continue reading “Klout Klok Tracks Your Popularity, Time” →

Roomba Used To Map Indoor Air Quality

July 20, 2011 by Mike Nathan 11 Comments

roomba_based_air_quality_tester

The next time you set off for a long day in the coal mines, forget the canary – bring your Roomba along instead!

While we are pretty sure that canaries are no longer used in the mining industry, this Roomba hack could make a suitable replacement if they were. A team from the Public Laboratory for Open Technology and Science (PLOTS) recently showed off a Roomba which they modified to test an area’s air quality. Using an Arduino and a volatile organic chemical (VOC) detecting air quality sensor, the Roomba goes about its normal business, lighting an LED any time it encounters overly contaminated air. When captured via a long exposure image, the process creates a “bad air” map of sorts, with the polluted areas highlighted by the glow of the LED.

While the Roomba currently only detects VOCs, the team plans on adding additional sensors in the near future to expand its functionality. The Roomba is merely a proof of concept at the moment, but we imagine that similar technology will be adapted for use in unmanned explorations of chemically hostile environments, if that hasn’t happened already.

[via DVice] [Image via TechnologyReview]

Output Up To 768 PWM Signals From One Arduino

July 20, 2011 by Mike Szczys 46 Comments

Here’s an Arduino library that will let you drive a very large number of LEDs. [Elco Jacobs], an electrical engineering student, is the author of the library. He has a work-study job that has him helping out others with their electrical projects and he was constantly being solicited for methods to control droves of light emitting diodes. This was the motivation that led him to produce the dazzling 16 RGB LED example seen in the video after the break.

His setup doesn’t use expensive LED drivers, but instead utilizes 595 shift registers which are both common and cheap. He calculates that it is possible to control up to 96 of these shift registers, each driving 8 LEDs, with reasonably satisfying results. This is thanks to his well-optimized code that manages to drive the clock pin of the registers at 1.33 MHz. This optimization is done by writing each command in assembly, which allows him to precisely count the cycles. Each individual pin takes 12-13 cycles to address, totally 9984 cycles at worst when addressing the maximum number of outputs.

[Elco] thinks this is as fast as he can make the routine run, but he is asking for help with testing. If you think you know how to squeeze out a few more cycles, make sure you join in on his forum thread.

Continue reading “Output Up To 768 PWM Signals From One Arduino” →

Beat707 LE: A Button Pad-based Standalone MIDI Sequencer

July 20, 2011 by Mike Nathan 10 Comments

[Guilherme] picked up a SparkFun Button Pad and was taking a closer look at the device when he noticed that it was based off the ATMega328 microcontroller. Since he loves working with MIDI, he thought that the Button Pad would make a slick yet compact standalone MIDI controller.

Since his ultimate goal was to create a completely standalone controller aside from the power plug and MIDI interface, it forced him to work quite closely with the ATMega chip. He and his partners spent a good deal of time working through some serial communications issues so as not to block the LEDs or MIDI block timer during operation. Ensuring that the Arduino doesn’t block any other functions is obviously important when you are building a MIDI timer, and it seems [Guilherme] was successful in his quest.

The MIDI controller works quite nicely as you can see in the videos below, great job!

Continue reading “Beat707 LE: A Button Pad-based Standalone MIDI Sequencer” →

Chilean Teen Builds Automatic Earthquake Alarm

July 19, 2011 by Mike Nathan 27 Comments

When an earthquake is about to strike in Chile, who do you think is first to sound the alarm? You might be surprised that it’s not the government, but rather a 14 year old boy.

After living through an earthquake in 2010 and seeing the devastation this spring in Japan, Chilean teenager [Sebastian Alegria] decided that he wanted to construct something similar to Japan’s earthquake warning system. He purchased an off the shelf earthquake detector for less than $100, and connected it to his computer via an Arduino.

Now, whenever seismic activity is detected, his sensor tweets an alert letting his 29,000+ followers know that a perceptible earthquake is 5 to 30 seconds away. Apparently the Chilean government is working on a similar system that is still at least a year away, so in the meantime his fellow citizens rely on [Sebastian] instead.

While it might seem like a relatively easy hack to pull off compared to other earthquake detectors, we’re impressed by [Sebastian’s] creativity, and his will to help others. He’s been pounding away at computers since he was about 4 years old and has several other popular Twitter-based projects under his belt already, so we won’t be surprised if we hear from him again in the future.