Flash Command Description - NXP Semiconductors freescale KV4 Series Reference Manual

Table of Contents

Functional Description

Erased ('1') and programmed ('0') bit states can degrade due to elapsed time and data

cycling (number of times a bit is erased and re-programmed). The lifetime of the erased

states is relative to the last erase operation. The lifetime of the programmed states is

measured from the last program time.

The 'user' and 'factory' levels become, in effect, a minimum safety margin; i.e. if the reads

pass at the tighter tolerances of the 'user' and 'factory' margins, then the 'normal' reads

have at least this much safety margin before they experience data loss.

The 'user' margin is a small delta to the normal read reference level. 'User' margin levels

can be employed to check that flash memory contents have adequate margin for normal

level read operations. If unexpected read results are encountered when checking flash

memory contents at the 'user' margin levels, loss of information might soon occur during

'normal' readout.

The 'factory' margin is a bigger deviation from the norm, a more stringent read criteria

that should only be attempted immediately (or very soon) after completion of an erase or

program command, early in the cycling life. 'Factory' margin levels can be used to check

that flash memory contents have adequate margin for long-term data retention at the

normal level setting. If unexpected results are encountered when checking flash memory

contents at 'factory' margin levels, the flash memory contents should be erased and

reprogrammed.

Factory margin levels must only be used during verify of the

initial factory programming.

32.4.10 Flash Command Description

This section describes all flash commands that can be launched by a command write

The flash memory module sets the FSTAT[ACCERR] bit and aborts the command

execution if any of the following illegal conditions occur:

• There is an unrecognized command code in the FCCOB FCMD field.

• There is an error in a FCCOB field for the specific commands. Refer to the error

handling table provided for each command.

Ensure that FSTAT[ACCERR] and FSTAT[FPVIOL] are cleared prior to starting the

command write sequence. As described in

new command cannot be launched while these error flags are set.

Launch the Command by Clearing

KV4x Reference Manual, Rev. 2, 02/2015

Freescale Semiconductor, Inc.