AVR Freaks

Although jumping to 0x00 will restart the program, it does not "reset" all of the registers to their reset values, so that is why that is not recommended.

Since the AVR does not have a reset instruction, so that leaves you with two possible ways to "reset" your chip, one using a bit of hardware or via software using the watchdog timer.

1)Hardware - You know that when the chip is reset all port pins become inputs, so connecting a jumper from any unused port pin to the reset pin will let you "reset" the chip by first setting the data direction register for the port pin to be an output, then writing a "0" to that pin, will force the reset pin low, thus resetting the chip, and when reset the port will also be reset back to an input, so this clears the low on the reset pin.

2)Software - When you want to reset the chip (yes it would be ok to do this in an ISR()), set up the watch dog timer for a short time out, usually the default timeout value, in reset mode, then loop until the reset happens.

ie. use a while(1){}; //loop here until reset by watchdog

Jim