LM3S6753 Datasheet, PDF (157/625 Pages) Texas Instruments – Stellaris LM3S6753 Microcontroller

Stellaris® LM3S6753 Microcontroller
8.3.1.2
8.3.1.3
8.3.2
To perform an erase of a 1-KB page
1. Write the page address to the FMA register.
2. Write the flash write key and the ERASE bit (a value of 0xA442.0002) to the FMC register.
3. Poll the FMC register until the ERASE bit is cleared.
To perform a mass erase of the flash
1. Write the flash write key and the MERASE bit (a value of 0xA442.0004) to the FMC register.
2. Poll the FMC register until the MERASE bit is cleared.
Nonvolatile Register Programming
This section discusses how to update registers that are resident within the Flash memory itself.
These registers exist in a separate space from the main Flash memory array and are not affected
by an ERASE or MASS ERASE operation. The bits in these registers can be changed from 1 to 0
with a write operation. Prior to being committed, the register contents are unaffected by any reset
condition except power-on reset, which returns the register contents to the original value. By
committing the register values using the COMT bit in the FMC register, the register contents become
nonvolatile and are therefore retained following power cycling. Once the register contents are
committed, the contents are permanent, and they cannot be restored to their factory default values.
With the exception of the USER_DBG register, the settings in these registers can be tested before
committing them to Flash memory. For the USER_DBG register, the data to be written is loaded
into the FMD register before it is committed. The FMD register is read only and does not allow the
USER_DBG operation to be tried before committing it to nonvolatile memory.
Important: These registers can only have bits changed from 1 to 0 by user programming. Once
committed, these registers cannot be restored to their factory default values.
In addition, the USER_REG0, USER_REG1, USER_REG2, USER_REG3, and USER_DBG registers
each use bit 31 (NW) to indicate that they have not been committed and bits in the register may be
changed from 1 to 0. These five registers can only be committed once whereas the Flash memory
protection registers may be committed multiple times. Table 8-2 on page 157 provides the FMA
address required for commitment of each of the registers and the source of the data to be written
when the FMC register is written with a value of 0xA442.0008. After writing the COMT bit, the user
may poll the FMC register to wait for the commit operation to complete.
Table 8-2. User-Programmable Flash Memory Resident Registers
Register to be Committed
FMPRE0
FMPRE1
FMPPE0
FMPPE1
USER_REG0
USER_REG1
USER_REG2
USER_REG3
USER_DBG
FMA Value
0x0000.0000
0x0000.0002
0x0000.0001
0x0000.0003
0x8000.0000
0x8000.0001
0x8000.0002
0x8000.0003
0x7510.0000
Data Source
FMPRE0
FMPRE1
FMPPE0
FMPPE1
USER_REG0
USER_REG1
USER_REG2
USER_REG3
FMD
April 05, 2010
157
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