Not reading any device code

[Ttelmah]

It looks like he has taken a circuit built to run at 3.3v, and powered it
up to 5v, without realising that the processor wiring has to change between
the 3.3v version and the 5v chip version. As gaugeguy says, this will almost
certainly have killed the processor. The 'core' of this chip is a 3.3v device.
It has the option to run at 5v (for the standard rather than the 'L' part),
but only by using the internal regulator.

[edaou]

Thank you for the responses. It does seem like the answer is that I didn't read the data-sheet properly enough to recognize the requirements for the 5V reference vs the 3.3v references