As unbelievable as it may sound, I have not been able to find an answer to this in the data sheet or forums.
My question is if I burn the fuses on an Atmega328p, can the fuses be written over later, or are they one time programmable?
Thanks for the help
It is not unbelievable. I don't fully understand the fuse bits, but I do know that you can rewrite them just like you can upload new sketches. However, you need to be very careful setting fuse bits because they configure how the chip operates, and thus how you can connect to reprogram it. For example, setting a fuse bit to use an external oscillator when none exists makes it so that you can't use the chip at all unless you wire up an external oscillator.
Maybe this is not the best tutorial, but it's where I got started: Beginning Embedded Electronics - 3 - SparkFun Electronics
it talks about oscillators, then goes on to explain fuse bits and gives a resource (AVR® Fuse Calculator – The Engbedded Blog) for calculating the fuses for your chip.
Also I believe the Atmega168 they use in the tutorial has the exact same fuse bits.
Hope that helps.