Freescale Semiconductor MCF51QE128RM manual 0x0 0x1 0x2 0x3 0x00000408, 0x0000040C, Nvprot, Nvopt

Chapter 4 Memory

Table 4-4. Reserved Flash Memory Addresses

Address	MSB1				LSB2
	(0x0)	(0x1)		(0x2)	(0x3)
0x(00)00_0408			Reserved
0x(00)00_040C	Reserved	NVPROT		Reserved	NVOPT

1MSB = most significant byte

2LSB = least significant byte

Table 4-5. Reserved Flash Memory Addresses

Address	Register	7		6	5	4		3	2	1		0
0x(00)00_03FC–	Reserved	—		—	—	—		—	—	—		—
0x(00)00_03FD
0x(00)00_03FE	Storage of	0		0	0	0		0	0	0		FTRIM
	FTRIM
0x(00)00_03FF	Storage of						TRIM
	ICSTRM
0x(00)00_0400–					8-Byte Backdoor Comparison Key
0x(00)00_0407
0x(00)00_0408–	Reserved	—		—	—	—		—	—	—		—
0x(00)00_040C
0x(00)00_040D	NVPROT					FPS						FPOPEN
0x(00)00_040E	Reserved	—		—	—	—		—	—	—		—
0x(00)00_040F	NVOPT		KEYEN		0	0		0	0		SEC

The factory trim values are stored in the flash information row (IFR)1 and are automatically loaded into the ICSTRM and ICSSC registers after any reset. The oscillator trim values stored in TRIM and FTRIM can be reprogrammed by third party programmers and must be copied into the corresponding ICS registers (ICSTRM and ICSSC) by user code to override the factory trim.

NOTE

When the MCU is in active BDM, the trim value in the IFR is not loaded. Instead, the ICSTRM register resets to 0x80 and ICSSC[FTRIM] resets to zero.

Provided the key enable (KEYEN) bit is set, the 8-byte comparison key can be used to temporarily disengage memory security. This key mechanism can be accessed only through user code running in secure memory (A security key cannot be entered directly through background debug commands). This security key can be disabled completely by clearing the KEYEN bit. If the security key is disabled, the only way

1.IFR — Nonvolatile information memory that can only be accessed during production test. During production test, system initialization, configuration, and test information is stored in the IFR. This information cannot be read or modified in normal user or background debug modes.

MCF51QE128 MCU Series Reference Manual, Rev. 3

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