You can select a AVR chip from the dropdown menu at the top of the page. If a chip is marked as "similar", it means that chip has identical fuses and preset collections as the currently selected chip
When you select another chip, the fuse settings from the current chip will be applied to the new chip (even if the chips are not similar).
Presets are known defined settings available for the AVR chip you've selected. Changing a preset setting will automatically apply the changes to the fuse bits.
Manually manipulating the fuse bits will also cause the calculator to find the preset that matches the fuse bit setting.
Be extra careful about anything with a star *, the star * means the setting is related to ISP programming. If ISP programming becomes disabled (by disabling SPI programming, disabling the reset pin, or enabling debugWIRE), you will require special equipment (HV programmer, parallel programmer, or something with debugWIRE) to change them back.
The AVRDUDE commands may be used as arguments with AVRDUDE to program the fuses.
Some bits that are undefined may not be verified as correct, but as they are undefined, that's usually not a problem.
Make sure you don't mess up your chip by disabling the programming features or locking the chip completely.
The information represented by the calculator is not guarenteed to be correct and no responsibility is taken for the correctness of any information represented. Please use this tool at your own risk.
Please submit any bug reports or comments to this blog post
Copyright 2009 Frank Zhao.