MK12DX256VLK5 POR problem

[larrydemuth]

I'm using the above micro and it doesn't seem to come out of reset on a power up. I can load and debug code using JTAG (JTAG reset works). But when I power cycle the board the micro seems stuck in reset. The board has a reset button connected to RESET_b and this will reset the micro and everything is fine. What would cause the micro to not come out of POR on power up?

I've been using other Kinetis micros for many (many) years and never had this problem. I'm stumped!

Vcc = 2.9V so should be high enough.

[larrydemuth]

Never mind, I found the problem. PTA4 (NMI) was being used as an input from another IC, and the pin was low on power up, causing an NMI interrupt. I set last word in the CFM PROT to 0xfffff9fe to disable NMI and EZPORT, it was 0xfffffffe.

The board now boots on power up.