Datasheet

56F8365 Technical Data, Rev. 9
132 Freescale Semiconductor
For details, see the JTAG Section in the 56F8300 Peripheral User Manual.
Note: Once the lockout recovery sequence has completed, the user must reset both the JTAG TAP controller
(by asserting TRST
) and the device (by asserting external chip reset) to return to normal unsecured
operation.
7.2.4 Product Analysis
The recommended method of unsecuring a programmed device for product analysis of field failures is via
the backdoor key access. The customer would need to supply Technical Support with the backdoor key
and the protocol to access the backdoor routine in the Flash. Additionally, the KEYEN bit that allows
backdoor key access must be set.
An alternative method for performing analysis on a secured hybrid controller would be to mass-erase and
reprogram the Flash with the original code, but to modify the security bytes.
To insure that a customer does not inadvertently lock himself out of the device during programming, it is
recommended that he program the backdoor access key first, his application code second, and the security
bytes within the FM configuration field last.