NXP Semiconductors Kinetis KE1xZ256, Reference Manual

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Before launching a command, the ACCERR and FPVIOL bits in the FSTAT register
must be zero and the CCIF flag must read 1 to verify that any previous command has
completed. If CCIF is zero, the previous command execution is still active, a new
command write sequence cannot be started, and all writes to the FCCOB registers are
ignored.
Attempts to launch an FTFE command in VLP mode will be ignored.
16.5.9.1.1 Load the FCCOB Registers
The user must load the FCCOB registers with all parameters required by the desired
FTFE command. The individual registers that make up the FCCOB data set can be
written in any order.
16.5.9.1.2 Launch the Command by Clearing CCIF
Once all relevant command parameters have been loaded, the user launches the command
by clearing the FSTAT[CCIF] bit by writing a '1' to it. The CCIF flag remains zero until
the FTFE command completes.
The FSTAT register contains a blocking mechanism, which prevents a new command
from launching (can't clear CCIF) if the previous command resulted in an access error
(FSTAT[ACCERR]=1) or a protection violation (FSTAT[FPVIOL]=1). In error
scenarios, two writes to FSTAT are required to initiate the next command: the first write
clears the error flags, the second write clears CCIF.
16.5.9.1.3 Command Execution and Error Reporting
The command processing has several steps:
1. The FTFE reads the command code and performs a series of parameter checks and
protection checks, if applicable, which are unique to each command.
If the parameter check fails, the FSTAT[ACCERR] (access error) flag is set.
ACCERR reports invalid instruction codes and out-of bounds addresses. Usually,
access errors suggest that the command was not set-up with valid parameters in the
FCCOB register group.
Program and erase commands also check the address to determine if the operation is
requested to execute on protected areas. If the protection check fails, the
FSTAT[FPVIOL] (protection error) flag is set.
Chapter 16 Flash Memory Module (FTFE)
Kinetis KE1xZ256 Sub-Family Reference Manual, Rev. 3, 07/2018
NXP Semiconductors 319