Clocking (or Overclocking) an AVR

Some guys build hot rods in their garage. Some guys overclock their PCs to ridiculously high clock frequencies (ahem… we might occasionally be guilty of this). [Nerd Ralph] decided to push an ATTiny13a to over twice its rated frequency.

It didn’t seem very difficult. [Ralph] used a 44.2 MHz can oscillator and set the device to use an external clock. He tested with a bit-banged UART and it worked as long as he kept the supply voltage at 5V. He also talks about some other ways to hack out an external oscillator to get higher than stock frequencies.

We wouldn’t suggest depending on an overclock on an important or commercial project. There could be long term effects or subtle issues. Naturally, you can’t depend on every part working the same at an untested frequency, either. But we’d be really interested in hear how you would test this overclocked chip for adverse effects.

Now, if you are just doing this for sport, a little liquid nitrogen will push your Arduino to 65 MHz (see the video after the break). We’ve covered pushing a 20MHz AVR to 30MHz before, but that’s a little less ratio than [Ralph] achieved.

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Tiny audio switcher eliminates repetitive plug swapping


[Phil] uses both his computer’s speakers and a set of headphones while working at his desk, but he was growing tired of constantly having to remove the headset from his sound card in order to insert the speaker plug. He’s been meaning to rig something up to make it easier to switch outputs, but never seemed to get around to it until he recently saw this LAN-enabled audio switcher we featured.

His USB-controlled switch features a single audio input and two audio outputs, which he mounted on a nicely done homemade double-sided PCB. The switch can be toggled using any terminal program, sending commands to the on-board ATtiny13A via an FT232R USB to serial UART chip.

The switch’s operation is really quite simple, merely requiring [Phil] to type in the desired audio channel into the terminal. The ATiny and a small relay do the rest, directing the audio to the proper output.

Hacked LED Christmas Lights

[Robert] wanted more out of his GE Color Effects G-35 LED Christmas lights. He reverse engineered and then hacked the protocol the lights use to communicate so that he can control each bulb. A 26-bit frame contains a 6-bit address, an 8-bit brightness value, and a 12-bit color value. The daisy chain topology of the data bus allows for modular bulbs with addresses enumerated during the startup of the string of lights. With this information, a 5 volt capable microcontroller is able to control a whole string of these lights with a refresh rate of up to 24Hz. In this case, [Robert] used an ATtiny13A microcontroller to control the string of lights. You can see a video of them in action after the break.

Also taken apart and analyzed, were the wireless transmitter and receiver that came with the lights, revealing a cheap ISM band receiver and transmitter module pair. Perhaps they will be useful for another project. We look forward to seeing people put these hacked lights to use throughout the year.

[via Make]

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