PIC16C74B-04I/P【PDF 12/184 页】IC MCU OTP 4KX14 A/D PWM 40DIP

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109

SAM7S Series [DATASHEET]

6175M–ATARM–26-Oct-12

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.

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.

Table 19-2.

Set of Commands

Command

Value

Mnemonic

Write page

0x01

Set Lock Bit

0x02

SLB

Write Page and Lock

0x03

WPL

Clear Lock Bit

0x04

CLB

Erase all

0x08

Set General-purpose NVM Bit

0x0B

SGPB

Clear General-purpose NVM Bit

0x0D

CGPB

Set Security Bit

0x0F

SSB

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