A really, really tiny microcontroller board

trinket

Here’s something very cool from the wonderful world of Adafruit: The Trinket, an Arduino compatible microcontroller platform that’s not only small enough to fit in your pocket, it’s small enough to lose in your pocket.

Like the similarly specced Digispark, the Trinket features an ATTiny85 microcontroller with 5 IO pins. Unlike the Digispark, the Trinket is a bit more substantial, featuring 3.3 and 5 Volt regulators along with a real USB port and mounting holes. As this is based on the ‘tiny85, it’s possible to connect this up to I2C and SPI sensors and peripherals

One thing to note about the Trinket is the fact that it’s so cheap. Either version of the Trinket goes for about $8, inexpensive enough to simply leave in a project when you’re done with it. Given the cool stuff we’ve already seen created with the Digispark, including a homebrew stepper motor and an Internet meme and lame pun assessment tool, we can’t wait to see what’s made with the Trinket,

Bluetooth stepper motor driver

bluetooth-stepper-motor-driver

[Dan] salvaged some parts from an old printer a while back and finally found some time to play with them. One of the things he was most interested in is the geared stepper motor seen above. He was able to get it running with an Arduino in no time so he decided to take the project a little bit further. What he ended up with is a stepper motor driver which can be controlled over Bluetooth.

The motor can’t be driven directly, but with a simple motor driver like the L293 chip [Dan] used it’s not hard to interface them with your control hardware of choice. From there he added an ATtiny85 which will take care of the stepping protocol necessary to move the motor. The Bluetooth module he’s using functions as a serial device, making it really simple to interface with the uC. [Dan] uses a pin header to connect the module, so switching to a different type of serial device in the future will be quick and painless.

After the break you can see him sending step commands to the driver board.

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Working 3D printed stepper motor

Stepper Small 1

Most 3D printers use stepper motors to control the movement of the extruder head. If you could actually print those motors it would be one more big step toward self-replicating hardware. Now obviously [Chris Hawkins'] working 3d printed stepper motor wasn’t built 100% through 3D printing, but the majority of the parts were. All that he had to add was the electronic driver pieces, magnets, wire, and a few nails.

The coils are made up of nails wrapped in magnet wire. The rotor is a 3D printed framework which accepts neodymium rare earth magnets. The axle is pointed which reduces the friction where it meets the cone-shaped support on either side of the frame. The IC on the upper right is a transistor array that facilitates switching the 20V driving the coils. The board on the lower right is a Digispark, which is an ATtiny85 breakout board that includes a USB edge connector for programming and a linear regulator which is how he gets away with feeding 20V as the source.

Don’t miss the demo video after the break where you can see the motor stepping 7.5 degrees at a time.

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Business card draws [ch00f]‘s logo

card

[ch00f] is at it again, expanding the horizons of the art of PCB business cards. This one draws his logo on any computer over a USB port.

The physical design of the card is heavily inspired by [Frank Zhao]‘s card; both use an ATtiny85 and the V-USB package to handle the USB protocol and communications. Instead of typing words into a text editor like [Frank]‘s, [ch00f]‘s card draws the ch00ftech logo in MS Paint or other image editor.

There was a problem with simply emulating the mouse to draw a logo on the screen, though; because different computers have different mouse settings for acceleration, the ch00ftech logo was nearly always distorted. [ch00f] fixed that by emulating an absolute input device, basically turning his business card into a single-function pen tablet.

The logo was traced by hand and put into a few arrays in the firmware. Surprisingly, the logo didn’t take up much space – only 4k of the tiny85’s flash is used. There’s a lot more space for a more complicated drawing, but for now the simple ch00ftech logo (video after the break) will do.

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Sonic Screwdriver meets TV-B-Gone

sonic

[furrysalamander] has a friend that is a really big Doctor Who fan. It happens that this friend has a birthday coming up, and [furrysalamander] wanted to get her something amazing. A Sonic Screwdriver is always a great gift, but [furrysalamander] wanted to put his personal touch on it. He ended up adding a TV-B-Gone to [10]‘s screwdriver, turning a fictional deus ex machina into a functional device.

The body of the Sonic comes from this replica of [10]‘s screwdriver from Think Geek. Inside, the screwdriver has space for a battery a circuit board to control the lights and sound normally expected of a sonic screwdriver. [furrysalamander] added a freeform circuit composed of an ATtiny85, a transistor, LED, and a few resistors to add the ability to turn just about any TV off.

Of course [furrysalamander] needed to program the ATtiny with the TV-B-Gone firmware, and lacking any AVR development tools he used a Raspberry Pi’s GPIO pins to write the firmware to the microcontroller. That’s something we’ve seen before, but [furrysalamander] is a champ for including the process in his Instructable.

The end result is a Sonic Screwdriver that doesn’t work on wood and can’t break a deadlock seal. It turns off TVs just fine, though, and looks great to boot. You can check out a demo of [furrysalamander]‘s sonic in action after the break.

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A pair of automatic fish feeders

a-pair-of-automatic-fish-feeders

Sometime the hacking topics come in waves. For instance, we were tipped off about this pair of automatic fish feeders just an hour apart from each other. Maybe it’s that time of year when people are about to go on Holiday and want to make sure their marine pets don’t go hungry?

The feeder on the left is a true hack. It’s built from a pair of servos and a pill bottle. An ATtiny85 drives the motors. One is mounted to the other, allowing the cap which catches and distributes the food to move along two axes. When it rotates into place under the pill bottle it bumps against a stick to open a flapper releasing more food.

On the right is a feeder that precisely doses the food. That’s because it includes a separate chamber for each feed. A worm gear drives the hopper, with screw heads pressing against a leaf switch for position feedback. This one is well designed and built to last.

An attempt to replace multiple RFID cards with a single hacked-together tag

rfid-multipass

It’s kind of a convoluted title, but [Hudson's] attempt to replace multiple HID Prox cards with one AVR chip didn’t fully pan out. The project started when he wanted to reduce the number of RFID access cards he carries for work down to just one. The cards use the HID Proximity protocol which is just a bit different from the protocols used in most of the hobby RFID projects we see. He ended up taking an AVR assembly file that worked with a different protocol and edited it for his needs.

The device above is the complete replacement tag [Hudson] used. It’s just an AVR ATtiny85 and a coil made of enameled wire. The coil pics up current from the card reader’s magnetic field, and powers the chip through the leakage on the input pins (we’ve seen this trick a few times before). The idea he had was to store multiple codes on the device and send them all in a row. He was able to get the tag to work for just one code, but the particulars of the HID Prox reader make it difficult if not impossible to send multiple codes. The card must send the same code twice in a row, then be removed from the magnetic field before the reader will poll for another combination.

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