NXP Semiconductors K22F series, Reference Manual, Page: 629 / 1407

Chapter 29
Flash Memory Module (FTFA)
29.1 Introduction
NOTE
For the chip-specific implementation details of this module's
instances, see the chip configuration information.
The flash memory module includes the following accessible memory regions:
• Program flash memory for vector space and code store
Flash memory is ideal for single-supply applications, permitting in-the-field erase and
reprogramming operations without the need for any external high voltage power sources.
The flash memory module includes a memory controller that executes commands to
modify flash memory contents. An erased bit reads '1' and a programmed bit reads '0'.
The programming operation is unidirectional; it can only move bits from the '1' state
(erased) to the '0' state (programmed). Only the erase operation restores bits from '0' to
'1'; bits cannot be programmed from a '0' to a '1'.
CAUTION
A flash memory location must be in the erased state before
being programmed. Cumulative programming of bits (back-to-
back program operations without an intervening erase) within a
flash memory location is not allowed. Re-programming of
existing 0s to 0 is not allowed as this overstresses the device.
The standard shipping condition for flash memory is erased
with security disabled. Data loss over time may occur due to
degradation of the erased ('1') states and/or programmed ('0')
states. Therefore, it is recommended that each flash block or
sector be re-erased immediately prior to factory programming
to ensure that the full data retention capability is achieved.
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 629