S912XHY128F0VLM Datasheet, PDF (619/802 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Chapter 19
128 KByte Flash Module (S12XFTMR128K1V1)
19.1 Introduction
The module implements the following:
• Kbytes of P-Flash (Program Flash) memory
• Kbytes of D-Flash (Data Flash) memory
The Flash memory is ideal for single-supply applications allowing for field reprogramming without
requiring external high voltage sources for program or erase operations. The Flash module includes a
memory controller that executes commands to modify Flash memory contents. The user interface to the
memory controller consists of the indexed Flash Common Command Object (FCCOB) register which is
written to with the command, global address, data, and any required command parameters. The memory
controller must complete the execution of a command before the FCCOB register can be written to with a
new command.
CAUTION
A Flash word or phrase must be in the erased state before being
programmed. Cumulative programming of bits within a Flash word or
phrase is not allowed.
The Flash memory may be read as bytes, aligned words, or misaligned words. Read access time is one bus
cycle for bytes and aligned words, and two bus cycles for misaligned words. For Flash memory, an erased
bit reads 1 and a programmed bit reads 0.
It is not possible to read from a Flash block while any command is executing on that specific Flash block.
It is possible to read from a Flash block while a command is executing on a different Flash block.
Both P-Flash and D-Flash memories are implemented with Error Correction Codes (ECC) that can resolve
single bit faults and detect double bit faults. For P-Flash memory, the ECC implementation requires that
programming be done on an aligned 8 byte basis (a Flash phrase). Since P-Flash memory is always read
by phrase, only one single bit fault in the phrase containing the byte or word accessed will be corrected.
19.1.1 Glossary
Command Write Sequence — An MCU instruction sequence to execute built-in algorithms (including
program and erase) on the Flash memory.
D-Flash Memory — The D-Flash memory constitutes the nonvolatile memory store for data.
MC9S12XHY-Family Reference Manual, Rev. 1.01
Freescale Semiconductor
619
Preliminary