SAM7S512_14 Datasheet, PDF (109/775 Pages) ATMEL Corporation – ARM-based Flash MCU

19.2.3 Write Operations
The internal memory area reserved for the embedded Flash can also be written through a write-only latch buffer.
Write operations take into account only the 8 lowest address bits and thus wrap around within the internal memory
area address space and appear to be repeated 1024 times within it.
Write operations can be prevented by programming the Memory Protection Unit of the product.
Writing 8-bit and 16-bit data is not allowed and may lead to unpredictable data corruption.
Write operations are performed in the number of wait states equal to the number of wait states for read operations
+ 1, except for FWS = 3 (see “MC Flash Mode Register” on page 115).
19.2.4 Flash Commands
The EFC offers a command set to manage programming the memory flash, locking and unlocking lock sectors,
consecutive programming and locking, and full Flash erasing.
Table 19-2. Set of Commands
Command
Write page
Set Lock Bit
Write Page and Lock
Clear Lock Bit
Erase all
Set General-purpose NVM Bit
Clear General-purpose NVM Bit
Set Security Bit
Value
0x01
0x02
0x03
0x04
0x08
0x0B
0x0D
0x0F
Mnemonic
WP
SLB
WPL
CLB
EA
SGPB
CGPB
SSB
To run one of these commands, the field FCMD of the MC_FCR register has to be written with the command num-
ber. As soon as the MC_FCR register is written, the FRDY flag is automatically cleared. Once the current
command is achieved, then the FRDY flag is automatically set. If an interrupt has been enabled by setting the bit
FRDY in MC_FMR, the interrupt line of the Memory Controller is activated.
All the commands are protected by the same keyword, which has to be written in the eight highest bits of the
MC_FCR register.
Writing MC_FCR with data that does not contain the correct key and/or with an invalid command has no effect on
the memory plane; however, the PROGE flag is set in the MC_FSR register. This flag is automatically cleared by a
read access to the MC_FSR register.
When the current command writes or erases a page in a locked region, the command has no effect on the whole
memory plane; however, the LOCKE flag is set in the MC_FSR register. This flag is automatically cleared by a read
access to the MC_FSR register.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
109