Magically repair AVR chips

If you’ve ever spent time working with AVR microcontrollers you’ve probably set the fuse bits incorrectly at least once. The ATmega fusebit doctor will automatically repair the fuse bits and get you back in business until your next mishap. The ATmega8 that powers the device has the chip signatures for the ATmega family stored inside so it will automatically detect which chip you’re trying to ‘unbrick’. From there it looks up the correct fuse bits and resurrects the sick microcontroller. This is useful in recovering a chip that has serial programming disabled, used the reset pin as I/O, or just enabled an external clock without the necessary hardware to deliver on that feature.

This magic is taken care of by using High Voltage Parallel Programming. We’ve seen HVPP used in the Arduino rescue shield and it is a valuable feature of the AVR Dragon, our favorite AVR programmer, as well as others. Still, you can hardly beat the ease of plugging a dead chip into this board and pressing one button. Oh, did you brick a member of the ATtiny family? There’s a rescue board for those too.

[Thanks Stewe]

Scratchbot: Whiskers to the rescue

Scratchbot is designed as a rescue bot, going places where there is low visibility. It’s defining feature is the fact that it uses “whiskers” to feel for things. We feel like this is a little gimmicky. If it is a low visibility situation, wouldn’t IR or audio, possibly sonar be a more effective? How would it differentiate between different physical obstacles? Are the whiskers really new? Aren’t they really just bump sensors? Maybe they have something a little more complicated going on. There was another recent bot that utilized whiskers and compared different tactile profiles to determine what it was touching.

AVR HV rescue shield


While playing with an ATmega168, [Jeff] programmed the RSTDISBL fuse bit. This pretty much makes the chip useless in most cases. [Jeff] didn’t want to give up on it though, so he built a system to program it using the rarely used high voltage parallel programming mode. He used an Arduino, a few lines of code and a few spare parts to make it. After sharing the idea with some fellow programmers, he decided to make an Arduino shield specifically for this purpose. You can use this to reset almost any fuse to rescue a chip. If you are a die hard AVR person and never started using Arduino instead, the STK500 actually has this built in.


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