MPC5644A Ver la hoja de datos (PDF) - Freescale Semiconductor

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Fabricante

MPC5644A

Microcontroller

Freescale Semiconductor 

and 128- and 256-bit read data interfaces to flash memory. The module contains a prefetch controller which prefetches

sequential lines of data from the flash array into the buffers. Prefetch buffer hits allow no-wait responses.

The flash memory provides the following features:

• Supports a 64-bit data bus for instruction fetch, CPU loads and DMA access. Byte, halfword, word and doubleword

reads are supported. Only aligned word and doubleword writes are supported.

• Fetch Accelerator

— Architected to optimize the performance of the flash

— Configurable read buffering and line prefetch support

— Four-entry 256-bit wide line read buffer

— Prefetch controller

• Hardware and software configurable read and write access protections on a per-master basis

• Interface to the flash array controller pipelined with a depth of one, allowing overlapped accesses to proceed in parallel

for interleaved or pipelined flash array designs

• Configurable access timing usable in a wide range of system frequencies

• Multiple-mapping support and mapping-based block access timing (0-31 additional cycles) usable for emulation of

other memory types

• Software programmable block program/erase restriction control

• Erase of selected block(s)

• Read page size of 128 bits (four words)

• ECC with single-bit correction, double-bit detection

• Program page size of 128 bits (four words) to accelerate programming

• ECC single-bit error corrections are visible to software

• Minimum program size is two consecutive 32-bit words, aligned on a 0-modulo-8 byte address, due to ECC

• Embedded hardware program and erase algorithm

• Erase suspend, program suspend and erase-suspended program

• Shadow information stored in non-volatile shadow block

• Independent program/erase of the shadow block

1.4.9 BAM

The BAM (Boot Assist Module) is a block of read-only memory that is programmed once by Freescale and is identical for all

MPC5644A MCUs. The BAM program is executed every time the MCU is powered-on or reset in normal mode. The BAM

supports different modes of booting. They are:

• Booting from internal flash memory

• Serial boot loading (A program is downloaded into RAM via eSCI or the FlexCAN and then executed)

• Booting from external memory on external bus

The BAM also reads the reset configuration half word (RCHW) from internal flash memory and configures the MPC5644A

hardware accordingly. The BAM provides the following features:

• Sets up MMU to cover all resources and mapping of all physical addresses to logical addresses with minimum address

translation

• Sets up MMU to allow user boot code to execute as either Power Architecture embedded category (default) or as

Freescale VLE code

• Location and detection of user boot code

• Automatic switch to serial boot mode if internal flash is blank or invalid

• Supports user programmable 64-bit password protection for serial boot mode

• Supports serial bootloading via FlexCAN bus and eSCI using Freescale protocol

MPC5644A Microcontroller Data Sheet, Rev. 7

10

Freescale Semiconductor

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