mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 508

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

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.
18.1.1
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.
D-Flash Sector — The D-Flash sector is the smallest portion of the D-Flash memory that can be erased.
The D-Flash sector consists of four 64 byte rows for a total of 256 bytes.
NVM Command Mode — An NVM mode using the CPU to setup the FCCOB register to pass parameters
required for Flash command execution.
Phrase — An aligned group of four 16-bit words within the P-Flash memory. Each phrase includes eight
ECC bits for single bit fault correction and double bit fault detection within the phrase.
P-Flash Memory — The P-Flash memory constitutes the main nonvolatile memory store for applications.
P-Flash Sector — The P-Flash sector is the smallest portion of the P-Flash memory that can be erased.
Each P-Flash sector contains 1024 bytes.
Program IFR — Nonvolatile information register located in the P-Flash block that contains the Device
ID, Version ID, and the Program Once field. The Program IFR is visible in the global memory map by
setting the PGMIFRON bit in the MMCCTL1 register.
Freescale Semiconductor
Glossary
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.
S12XS Family Reference Manual, Rev. 1.10
CAUTION
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