mcf5282 Freescale Semiconductor, Inc, mcf5282 Datasheet - Page 114

• Manufacturer Part Number: mcf5282
• Manufacturer: Freescale Semiconductor, Inc

ColdFire Flash Module (CFM)
6.2
Block Diagram
The CFM module shown in
Figure 6-1
contains the Flash physical blocks, the ColdFire Flash bus and IP
bus interfaces, Flash interface, register blocks, and the BIST engine.
Each 128-Kbyte Flash physical block is arranged as two 32,768-word (16 bits) memory arrays. Each of
these memory arrays is designated as xH or xL, where x represents one of the four Flash physical blocks
(0–3) and H/L represents the high or low 16 bits of each longword of logical memory. Each of these words
may be read as either individual bytes or aligned words. Aligned longword access is provided by
concatenating the outputs of the each of the two memory arrays within the Flash physical block. Simple
reads of bytes, aligned words, and aligned longwords require two 66-MHz clock cycles, although the
processor’s Flash interface includes logic that reduces the effective access time through two-way longword
interleaving and speculative reads.
Flash physical blocks are interleaved on longword (4-byte) boundaries. Therefore, all Flash program,
erase, and verify commands operate on adjacent Flash physical blocks and are initiated with a single
aligned 32-bit write to the appropriate array location. Any other write operation will cause a cycle
termination transfer error. Page erase operates simultaneously on two interleaving erase pages in adjacent
Flash physical blocks. Each Flash physical block is organized as 1024 rows of 128 bytes with a single erase
page consisting of 8 rows (1024 bytes). Since page erase operates simultaneously on two interleaving and
adjacent physical Flash blocks, each erase row is comprised of four 16-bit entries in each of two memory
arrays within each of two Flash physical blocks. The first row of Flash is made up of 0H_0L_1H_1L [0]
through 0H_0L_1H_1L [31], where each [n] represents four 16-bit words from each memory array in each
of two physical blocks, for a total of 256 bytes. Since a single erase page consists of 8 rows of 256 bytes,
or 2048 bytes, the first erase page is physically located at 0H_0L_1H_1L [0] through 0H_0L_1H_1L
[255]. Mass erase operates simultaneously on two adjacent Flash physical blocks in their entirety and
erases a total of 256 Kbytes of Flash space. Therefore, it takes two mass erase operations, one on mass
erase block 0 and one on mass erase block 1, to erase the full 512K CFM Flash on the MCF5282 and
MCF5216.
An erased Flash bit reads 1 and a programmed Flash bit reads 0. The CFM features a sense amplifier
timeout (SATO) block that automatically reduces current consumption during reads at low system clock
frequencies.
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3
6-2
Freescale Semiconductor