Self-balancing Arduino Does It Without An IMU

September 26, 2013 by Mike Szczys 15 Comments

The miniscule size of this self-balancing robot makes it a cool project. It actually uses the motor and wheels from a small toy car. But when you look into how the balancing act is performed it gets way more interesting. The larger versions of this trick pretty much all use Inertial Measurement Units (IMUs) which are usually made up of an accelerometer and a gyroscopic sensor. This has neither.

The black PCB seen to the right of the robot is an IR reflectance sensor. It shines an IR led at the floor and picks up what reflects back. [Sean] added this hack because the gyro sensor he ordered hasn’t arrived yet. The board has a trimpot which is used to adjust the sensitivity. You have to tweak it until it stands on its own. See for yourself after the break.

Self balancing robot builds are a great way to teach yourself about Proportional-Integral-Derivate (PID) algorithms used in a lot of these projects.

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Arduino-based Temp Control Via SMS

September 25, 2013 by Marsh 7 Comments

smsTempController

As connected as we are, reliable and affordable internet is still a luxury in the far reaches. [kohleick’s] country home is not just remote; with temperatures dropping to -30C in the winter, it’s practically Arctic. His solution for controlling the thermostat from afar was to take advantage of the GSM network and implement a SMS-based heater controller. The unit typically operates in “antifreeze mode,” but sending a simple text message prior to visiting causes the heater to kick it up to a more comfortable setting for your arrival. Daily logs report the system’s status, and an alert will trigger when temperatures fall below a set limit, thus indicating potential faults with the heater.

The build uses a Freeduino paired with an external GSM modem for communication and an LCD to display current status and menus, which users access via three buttons on the side of the picture frame. [kohleick] connected two temperature sensors: one directly to the Freeduino’s shield and a second outside the house. After the temperature sensors detect deviance from the set point, or upon SMS instruction, the Freeduino will crank up the heat through a 5V relay attached to the home’s boiler. Head over to the Instructables page linked above for a bill of materials, schematics, and the code. The Siemens GSM modem in this build is nothing to worry about, but be careful if you try to reproduce this project with an Arduino GSM shield, or your house might really heat up.

Automatic Bluetooth Module Programmer

September 24, 2013 by Mike Szczys 9 Comments

automatic-bluetooth-programming

Before we dive in don’t be confused by the title. This doesn’t flash firmware to the device. But it does automate the process of setting up the Bluetooth to serial module for use in your projects.

We’re often confused by the lack of a standard way of describing these inexpensive modules. We would look at this can call it an HC-05, but we’re not sure if that’s right or not. [James Daniel] calls it a JY-MCU board. If you have a handle on the differences (or lack of) please let us know in the comments. Either way we know that these boards can be frustrating to work with. They can be found with a wide variety of different firmwares, which can make the configuration process a bit different for each.

[James’] solution connects the device to an Arduino running a sketch that he wrote. Connect the device, launch the terminal monitor in the Arduino IDE, then give it your desired settings. The sketch will poll the Bluetooth module to see what speed it is set to run at. It will then establish which firmware version the board is running, displaying this info in the terminal. It then uses that information to program the board with your desired settings.

In this case [James] is using one of the modules to drive his 3D printer without being tethered to his laptop.

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Safety Warning: Arduino GSM Shield May Cause Fires

September 24, 2013 by Adam Fabio 133 Comments

Be careful with those Arduino GSM cards. As [James] reports, they may turn into fire starters. One person has reported a small explosion and fire already on the Arduino forums.
Now before we go any further – You may be asking yourself who the heck [James] is, and what gives him the ability to second guess the Arduino team. Well, here is [James’] blog disclaimer: “James is a Senior Technical Expert for Technology and Applications at KEMET Electronics, a capacitor manufacturer. The content of this post are his and in no way reflects opinions of his employer.”

Senior Technical Expert? That’s a good enough reason for us to believe him.

[James] states the problem is a tantalum capacitor used to decouple the GSM radio power supply from the main Arduino supply.
Tantalum capacitors are great for their low ESR properties. However, they have a well known downside of getting very hot, or even exploding when stressed. It’s not the Tantalum Anode that is burning. The Manganese Dioxide used as a cathode in some Tantalum capacitors is the culprit. Continue reading “Safety Warning: Arduino GSM Shield May Cause Fires” →

Talkbot: An Arduino-driven Robot For Beginners

September 21, 2013 by Marsh 5 Comments

talkbotguts

It isn’t exactly WALL-E, but [Bithead’s] affordable introduction to robots — Talkbot — is made out of a trash can. This little guy runs off an Arduino and comes packed with features, including a voice chip, a motor shield, and a pair of bump sensors. Talkbot will cruise around until a bump sensor slams into an obstacle. One of his prerecorded messages will then play through the speaker while he backs up, turns, and tries to find a clearer path.

According to [Bithead’s] build log, tracking down the right bargain voice chip was a bit of a hassle; he skipped over the text-to-speech options only to be stalled by vendor issues. He finally settled on a clone of Sparkfun’s WTV020SD chip sourced from eBay, which allows you to access pre-recorded WAV files stored on a Micro-SD card. The robot’s body comes straight off the hardware store shelf, with PVC pipe for arms and a polystyrene base to hold all the parts. At the bargain price of $110, [Bithead’s] students will have a true hacker experience cobbling the Talkbot together rather than using a prefab kit.

Be sure to see Talkbot in a video below, performing either his green-eyed “friendly mode” or red-eyed “grumpy mode,” which dictates how pleasantly he responds to obstacles. Need something more advanced? Check out the tentacle robot, just in time for Halloween.

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FLASH.IT: The RGB LED Climbing Wall

September 19, 2013 by Marsh 11 Comments

rockWallLEDs2

[Chris] and his friends were kicking around ideas for a Burning Man project, and this is the one that stuck: a rock climbing wall with RGB LEDs embedded in the holds. The holds themselves were custom made; the group started by making silicone molds of varying shapes and sizes, then added the electronics and poured in polyurethane resin to create the casting. The boards for these LEDs are equipped with a central hole that pairs up with a peg in the silicone mold. [Chris] also solved an annoying spinning problem by affixing a bolt to the far end of the LED board: once embedded in the polyurethane, the bolt provides resistance that the thin board cannot. The finished holds bolt onto the wall with all their wires neatly sticking out of the back to be hooked up to a central controller.

The Instrucables page suggests a few ways to get the lights working, including grabbing the nearest Arduino and relying on the Neopixel Library from Adafruit. [Chris] went the extra mile for Burning Man, however, designing Arduino-software-compatible controller boards capable of communicating via DMX, which expanded the system from a simple display to one capable of more complex lighting control. Stop by the Github for schematics and PCB layouts, and stick around for a video of the wall after the break. If the thrill-seeking outdoorsman inside you yearns for more, check out WALL-O-TRON from earlier this summer.

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Hacking A Disco Laser

September 18, 2013 by James Hobson 18 Comments

hacked laser disco

[Mark] was looking for a cheap disco laser projector for parties, and he found one. Unfortunately for him, the advertised features were a bit lacking. The “sound activation mode” was merely an on off circuit, as opposed to it actually being controlled by the music — he set out to fix this.

Taking the unit apart revealed a very convenient design for hacking. All of the components were connected to the main PCB by connectors, meaning the laser driver board was completely separate! He replaced the PCB completely using a prototyping board, an Arduino pro mini, a microphone with a simple preamp, a rotary encoder, and a MSGEQ7 chip to analyse the levels. Oh, and a MOSFET to control the motor via PWM output. It even ended up being close to the same size as the original!

If you happen to have one of these projectors and want to fix it too, he’s posted the source code and circuit diagram on github.

After the break, check out the before and after video. It’s still a cheap disco laser projector, but at least it works as advertised now!

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