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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
480 of 571
NXP Semiconductors
UM10316
Chapter 28: LPC29xx Flash/EEPROM
•
Sector security
Remark:
It is not possible to erase the index sector. As a result the sector is write-only
and enabled features cannot be disabled again.
In the following sections these features and the procedures to enable them are described
in detail.
Remark:
As the index sector shares the address space of the regular sectors it is not
possible to access it via code in flash. Accessing is only possible via code outside flash
memory (e.g. internal RAM).
Remark:
Take care when writing locations in the index sector. The sector cannot be
erased, and using unspecified values or locations might result in a corrupted or
malfunctioning device which cannot be recovered.
2.6.1 Index sector programming
During index sector programming it is necessary to disable ECC. In the FTCR register, set
bits 29 and 28 to disable ECC. The other bits in FTCTR should not be changed (0). The
following code example shows how to disable ECC and unprotect the index sector:
/* unprotect index sector */
FMC_INX_SECTOR = UNPROTECT;
FCTR = (FS_ISS| FS_LOADREQ | FS_WPB | FS_WEB | FS_WRE | FS_CS);
FTCTR=(FTCTR |(1<<29)|(1<<28)); /* disable error correction! */
/* re enable ECC */
FTCTR=(FTCTR & 0xCFFFFFFF);
2.6.2 Index sector customer info
The index sector can also be used to program customer-specific information. Index sector
page 5 (32 flash words) can be programmed at the customer’s discretion. The range
available for this purpose is shown in
2.6.3 JTAG security
Two levels of security can be implemented in the LPC29xx:
1. Soft Security: To enable JTAG security, program 128 bits of the index sector address
starting at 0x2000 0A30 with 0x7FFF FFFF. JTAG access is now disabled but can be
re-enabled by software. In this case software must enable JTAG during startup before
the counter in the security block reaches 0. Otherwise the JTAG remains disabled.
2. Hard Security: JTAG access disabled and unable to re-enable.
The JTAG is disabled if the index sector is appropriately programmed. The setting for the
JTAG security in the flash index sector is reflected in the CFID register (see
).
To re-enable JTAG and override this JTAG security setting, it is necessary to have a piece
of code in the Flash (in the user program or application) that sets bit 0 in the SEC_DIS
Table 411. Customer-specific information
Index Sector Page #
(FS_ISS bit set)
Customer Info
Address Range
5
0x2000 0A40
0x2000 0BFF