Circuit Design For Multiple UART Connections

June 28, 2011 by Mike Szczys 28 Comments

[Bill Porter] has a tip for designing circuits that have multiple connections to a single microcontroller UART. This stemmed from a review of a friend’s circuit design that used the UART in the project, but also called for an FTDI chip in order to reprogram via USB and a bootloader. Unlike the schematic above, the circuit called for straight connections without any resistors. With that design, a conflict will occur if two devices are connected and attempting to communicate at the same time.

The fix is easy. [Bill] discusses how to prioritize the connection by adding the pair of current limiting resistors seen above. This helps to ensure that damage will not occur, and that the FTDI chip will take precedence. Now the external hardware will not preclude the FTDI chip from accessing and programming via the bootloader. The tutorial is intended for those rolling their own boards out of an Arduino-based prototype, but it will work in any situation where you need multiple connections to a single set of UART pins.

Teamspeak Button Uses Tattoo Machine Foot Switch

June 27, 2011 by Brian Benchoff 11 Comments

As an avid gamer, [Pat Norton] uses Teamspeak with his friends when playing World of Warcraft. [Pat]’s friends were annoyed with the voice-activated option for Teamspeak and the constant squeaking of dog toys, and [Pat] was annoyed with the questionable usability of a push-to-talk key. Dissatisfied with his options, [Pat] built footswitch-controlled teamspeak button using a Teensyduino and a broken tattoo machine foot switch.

The Teensyduino is an incredibly small Arduino compatible board that was perfect for this project. Since the teensyduino can operate as a USB Human Interface Device, it’s very easy to have the board appear as another keyboard to the computer. After borrowing some code from the hardware button of a DIY photobooth, [Pat] hooked up the foot switch to two pins of the board. From there, it was very to adapt the code so the foot switch would act as a third ‘Control’ button. The results look very professional, like a factory-made game controller. We’ve seen a few foot switch keyboard devices before, and while this probably isn’t the most efficient way to have a foot switch button control something on a computer, it’s certainly the smallest we’ve seen.

Digitized Retro LCD Games Played Using An Arduino As A Controller

June 26, 2011 by Mike Szczys 12 Comments

This one’s a bit abstract. Remember those LCD games that became quite popular sometime in the 1990’s? You know, the ones that had only one game, usually a character that could be moved back and forth to catch, hit, or block objects falling from the sky or being thrown by some villain? [Tobie Nortje] sure remembers them and has built an Arduino controller to play virtual versions of the games.

He started off by finding a website that is digitizing the old games. That is to say, they’ve taken images of each state of the LCD, then implemented the game play using those images and an approximation of the original physics. Unlike NES or Sega Master System games the ROMs of these devices can’t just be dumped because of the specialized screen. Instead, a virtual version of the hardware has been built into a web interface.

[Tobie’s] part of the hack is to use an Arduino and a few buttons as the controller. It’s easy to set up and we think the breadboarded controller approximates the size and weight of an LCD game pretty well. Check out the video after the break and let us know what you think in the comments.

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Twitter Notifier Lets Us Know How Awesome We Are

June 22, 2011 by Mike Nathan 14 Comments

Let’s admit it, you’re just a little bit vain. Heck, we’re all just a little bit vain when you really think about it. Instructables user [pdxnat] was self-absorbed enough that he constructed an LED “mood light” that alerts him each time someone mentions his user name on Twitter.

The build is pretty simple, with most of the work being done on his PC. His Arduino is wired to a simple RGB LED that calmly cycles through various colors until someone mentions his name on Twitter. At that point, the client software running on his PC passes a message to the Arduino over a serial interface, causing it to wildly pulse the LED. Once it catches his eye, he stops the alert cycle with the press of the reset button, returning the LED to its previous state. As a bonus, he decided to write the Twitter-polling application in both Processing and Python, enabling fans of either language to easily replicate his work.

It’s a pretty cool idea, and it would be great to see someone expand it to include other online services to provide a greater overall feel for how awesome they really are.

Keep reading to see a quick video of the notifier in action.

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Roomba Shares All Of Its Daily Activity On The Web

June 21, 2011 by Mike Nathan 10 Comments

Instructables user [matchlighter] wanted to see what he could program his Roomba to do, so he decided he would make his little cleaning machine report its status on Twitter whenever something happened.

He popped open the Roomba’s case to access its serial connector, crafting a simple interface cable from some spare Cat5 he had sitting around. He added a small voltage regulator between the Roomba and his Arduino in order to protect it from the high power output present while the Roomba is charging. Once the proper bits were in place, he hooked the Roomba’s serial interface to the Arduino and attached a SparkFun WiFly shield to allow for wireless communications. After a bit of coding, the Roomba was sharing its activities with the entire world on Twitter.

Not only did he want the Roomba to tweet, but he decided that he also wanted the ability to control it from the web. He created a simple interface using a handy library he found online and was sending cleaning commands to the Roomba in short order.

While there is no video of the Roomba in action, you can check out what it is up to here, and there’s plenty of code to be had on his Instructables page.

Arduinos…. In…. Spaaaaaace…..

June 20, 2011 by Brian Benchoff 37 Comments

Since 2007, [Adam Kemp] has been leading a team of students from Thomas Jefferson High School, guiding them through the process of designing and building a small satellite that NASA selected for launch early next year.

The CubeSat, officially named TJ³Sat, uses commercial, off-the-shelf components for nearly all its systems. The team ran into a problem interfacing the FM430 Flight Module (PDF warning), so [Adam] designed an Arduino-based replacement. Based on an ATMEGA328, the entire board is a drop-in replacement for the FM430 Flight Module. On July 1st, the TJ³Sat will begin testing at Orbital Sciences Corp. to make sure the entire satellite is up to snuff.

The TJ³Sat’s payload will take data from the ground controllers and using a TextSpeak module convert serial data into spoken voice. This audio will then be transmitted over amateur radio frequencies and will be picked up by hams all over the world. We’d like to wish the students at Thomas Jefferson High a hearty congratulations for being the first High School to build a satellite and hope the testing and launch go as planned.

The Perfect Beer Every Time

June 18, 2011 by Nick Schulze 26 Comments

The Pour Master Pro is a beer pouring robot, designed and built by a team of beer/robot lovers as their entry to the Red Bull’s Creation Contest. Pour Master keeps it simple (opposed to some of the other bar bots we have seen), it uses a modified kegerator and tap for the beer, and a few sensors which it uses to maintain its state and pour the perfect beer. The standard tower on the kegerator was replaced with a rack and pinion driven tower constructed using the Vex Robotics Design System, this allows the Pour Master to set its height to the size of any glass using a limit switch and a set of ultrasonic rangefinders.

For a perfect pour the beer must not spill over the side of the glass and needs a decent 3/4″ head, to manage this the Pour Master uses the ultrasonic rangefinder to detect the thickness and height of the head. The entire thing is controlled by an Arduino running a finite state machine which provides state feedback to the user with an LCD display. Check out the video after the break for their competition entry, now all you need is one robot to make the beer and why not another to drink it.

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