Information

Chapter 28
Flash Memory Module (FTFL)
28.1 Introduction
NOTE
For the chip-specific implementation details of this module's
instances see the chip configuration chapter.
The FTFL module includes the following accessible memory regions:
• Program flash memory for vector space and code store
• Programming acceleration RAM to speed flash programming
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 FTFL 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')
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 603