Freescale Semiconductor MCF51QE128RM manual Features, Lov-Voltage Programming Sequence Example

Chapter 4 Memory

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.

Array read access time is one bus cycle for bytes, aligned words, and aligned longwords. Multiple accesses are needed for misaligned words and longword operands. 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.

CAUTION

A flash block address must be in the erased state before being programmed. Cumulative programming of bits within a flash block address is not allowed except for status field updates required in EEPROM emulation applications.

Flash memory on MCF51QE128/64/32 must be programmed 32-bits at a time when the low-voltage detect flag (LVDF) in the system power management status and control 1 register (SPMSC1) is clear. If SPMSC1[LVDF] is set, the programming sequence must be modified such that odd and even bytes are written separately. The MCF51QE128/64/32 flash memory is organized as two 16-bit wide blocks interleaved to yield a 32-bit data path. When programming flash when LVDF is set, alternate bytes must be set to 0xFF as shown in Table 4-8. Failure to adhere to these guidelines may result in a partially programmed flash array.

Table 4-8. Lov-Voltage Programming Sequence Example

Addresses	Desired Value	Values Programmed
0x00 – 0x03	0x5555_AAAA	0x55FF_AAFF
0x00 – 0x03		0xFF55_FFAA
0x04 – 0x07	0xCCCC_CCCC	0xCCFF_CCFF
0x04 – 0x07		0xFFCC_FFCC
0x08 – 0x0B	0x1234_5678	0x12FF_56FF
0x08 – 0x0B		0xFF34_FF78
0x0C – 0x0F	0x9ABC_DEF0	0x9AFF_DEFF
0x0C – 0x0F		0xFFBC_FFF0

4.4.1Features

Features of the flash memory include:

•Flash size

—MCF51QE128: 131,072 bytes (128 sectors of 1024 bytes each)

—MCF51QE64: 65,536 bytes (64 sectors of 1024 bytes each)

—MCF51QE32: 32,768 bytes (32 sectors of 1024 bytes each)

•Automated program and erase algorithm

•Fast program and sector erase operation

•Burst program command for faster flash array program times

•Single power supply program and erase

MCF51QE128 MCU Series Reference Manual, Rev. 3

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