TM4C129XNCZAD Datasheet, PDF (660/2191 Pages) Texas Instruments – Tiva Microcontroller

Internal Memory
Register 3: Flash Memory Control (FMC), offset 0x008
When this register is written, the Flash memory controller initiates the appropriate access cycle for
the location specified by the Flash Memory Address (FMA) register (see page 658). If the access
is a write access, the data contained in the Flash Memory Data (FMD) register (see page 659) is
written to the specified address.
For non-volatile registers, FMPREn, FMPPEn, USER_REGn, and USER_REGn, the respective
register is programmed with the value to be written rather than the FMD register.
This register must be the final register written and initiates the memory operation. The four control
bits in the lower byte of this register are used to initiate memory operations.
Care must be taken not to set multiple control bits as the results of such an operation are
unpredictable.
Flash Memory Control (FMC)
Base 0x400F.D000
Offset 0x008
Type RW, reset 0x0000.0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
WRKEY
Type WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
WO
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
reserved
COMT MERASE ERASE WRITE
Type RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RO
RW
RW
RW
RW
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit/Field
31:16
15:4
Name
WRKEY
reserved
Type
WO
RO
Reset
0x0000
0x00
Description
Flash Memory Write Key
This field contains a write key, which is used to minimize the incidence
of accidental Flash memory writes. The value 0xA442 or the PEKEY
value in the FLPEKEY register must be written into this field for a Flash
memory write to occur. The use of 0xA442 or PEKEY is dependent on
the value of the KEY bit in the BOOTCFG register at 0x1D0.
Writes to the FMC register without this WRKEY value are ignored. A read
of this field returns the value 0.
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
660
June 18, 2014
Texas Instruments-Production Data