Tic Tac Clock


Here’s an excuse to eat a bunch of Tic Tac candies: once the container is empty it makes a nice little enclosure for your next project. This particular offering introduces a point-to-point clock project that’s a ton of fun.

[Danny Chouinard] did a lot with very little. You can get the gist of the circuit just by looking at the photos above. it uses a 3×5 Charlieplexed LED display (this is given away by the fact that there’s only a few resistors on the board. A bit difficult to see, but between the resistors and the ATtiny84 there is a clock crystal, and on the back is a little piezo buzzer. The one thing that isn’t completely obvious is the power source. Two AAAA batteries, salvaged from a 9V battery, are able to keep the unit running at an estimated 2 years of moderate use.

The video after the break is worth a look though. It shows the various characters and information that can be flashed on the LED matrix. At first it’s hard to tell that the single user input button is being pressed by [Danny's] thumb.

If you don’t want to build a clock, there are still plenty of reasons to eat a whole container of these mints. You could replace them with a PIC programmer or a discreet camera.

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ATtiny84 Powered Minimalist LED Clock

LED Clock ATtiny84

We feature a lot of clock builds on HaD, and the reason is that they are cool. Even simple ones are cool. Not everyone can say they built a clock. [Chris] took a ride on the DIY Clock train and came up with this LED-based clock that is controlled by an ATtiny84 chip.

The clock has 24 LEDs total, 1 for each hour and 1 for every 5 minute increment. The 24 LEDs are arranged in 2 concentric rings. To display the hour, both LEDs at the same angle are lit up. To show the minutes, just the inner LED is lit. The main image above shows 6:40.

If you are familiar with the ATtiny84 you know that it only has 12 in/out pins, which is significantly less than the amount of LEDs that need controlling. [Chris] decided to use some 74HC595 shift registers to increase the IO pins on the ATtiny. The entire build is installed on a protoboard with quite a bit of point-to-point wiring. A simple tinted plastic case finishes the project and gives it a modern look.

[Chris] made the code for his clock available in case any readers are interested in making one.

LED Clock ATtiny84


Simple NFC Tag

[Nicholas] built a simple NFC tag using an ATtiny84 microcontroller, four resistors, three capacitors, a diode, and an antenna. It implements ISO 14443-3, a standard for identification cards, and can communicate with the NFC chip sets found in most new smartphones.

This standard uses on-off keying for communication, which makes the hardware slightly more complex than the AVR RFID tag that we saw a few years back. The antenna and a variable capacitor form an LC circuit tuned at 13.56 MHz, which is the carrier frequency for the protocol. The diode acts as an envelope detector, letting the microcontroller recover the signal.

It may not be fully compliant with the standard, but [Nicolas] successfully tested out the device with his Lumia 620 phone. The firmware is available on Google Code so you can program your own tag data into main.c, build the firmware, and send some NFC packets. You can also check out a demo of the device after the break.

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Haunted Dollhouse Microcontroller Networking for World Maker Faire


It’s pretty awesome to get see the number of projects presented at World Maker Faire. But we still love digging into the gritty details that only an in-depth build post can deliver. Here we get both. You can see the circuits pictured above in the Circuit Castle exhibit at WMF this weekend, and you can read about how the microcontroller network was built in [Jim's] article.

As the title states, this is a network built for a dollhouse. Each slave device performs a different task; adding color, sound, motion, and interactivity using some sensors.  The post discusses the i2c (or TWI to get around licensing issues as [Jim] mentions) communications used to talk to the ATtiny85 chips on the slave boards. Because the eight-pin package leaves few I/O pins to work with an ATtiny84 was also added. It brings 14-pins to the party, including multiple ADC inputs for reading sensors.

If this ends up being too much of a read for you jog to the “Update 9/17/13″ to get the general overview of progress. Like any project on a timeline, not everything works quite as well as they would have liked it to. But it’s the journey that makes something like this so fun — a fully working project would signal an end to the enjoyment, right?

[via Workshop 88]

Doorbell to Internet bridge also useful for other home automation

This wireless doorbell hack can send a text message when someone rings. Adding the hardware to the chime unit turned out to be quite simple. It shows potential for a slew of other applications.

[Martin] started the project with a breakout board he had designed for an RFM12B wireless transceiver board. This board is popular because of its low-cost, small size, and ease of operation. [Martin's] breakout is barely larger than the RFM module itself, and merely adds an ATtiny84 to the mix. In the case of this doorbell project he uses a pin interrupt to detect when the doorbell’s LED is illuminated. This wakes the chip from sleep and sends a message back to the receiver that something has happened.

The receiver can do anything it wants with that data. In this case it uses an email-to-SMS service to send [Martin] a text message. But the home automation applications are vast for this simple hardware. We have a water heater that is not near a floor drain so we use a simple leak detector to sound an alarm if there is ever a problem (the water heater sits in a shallow tray). That works if we’re home at the time. Using [Martin's] solution could extend that alarm’s reach worldwide.

[via Hacked Gadgets]

Autonomous Bassline Generator

We’ve been watching this project ever since [Dann] emailed us about the first prototype back in September. This bassline generator has a lot of functions we like, such as an adjustable melody seed, light-sensitive controls, and device interactivity. Line up a row of them and they’ll sync up the beat, building layers of sound on top of each other (see the first video after the break).

The system is built around an ATtiny84, putting its pulse width modulation channels to work for sound generation. [Dann] has some kits available but he’s also posted everything – the schematics, PCB layout, and code – if you want to throw one together on a breadboard.

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