Dan White

Trouble programming FSEC to the recommended secure state

Discussion created by Dan White on Dec 29, 2006
Latest reply on Jan 3, 2007 by Dan White
CPU: MC9S12XDT256
 
I am enabling security in my application by programming the address $FF0F to $BD. The problem is that my programmer (P&E Cyclone Pro) fails verification and says that address reads as $BC. According to the CPU user manual, the preferred state of the SEC (least significant) bits to enable security is 01 even though it says that 00 is also secure. If I change my code to set the security byte to $BC, then it passes verification. So, I may leave it that way even though it is not "preferrred". I can't find anywhere in to user manual or app notes that says this one bit can't be left erased or can't be read back.
 
Does anyone have a clue why this one byte won't verify?
 

Outcomes