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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Flash Program Memory
Flash Program Memory
Flash Memory Read/Write Operations
The flash memory can be read from and written to using register operations. To ensure protection
of application data certain protection measures have to be first carried out before any read and
write operations are executed on the Flash Memory.
Unlocking the Flash Memory
Before writing data to the Flash Memory it must first be unlocked. This is implemented by writing
a correct data sequence to the Flash Memory Unlock key register, FMKEY. It is recommended
to write the data sequence to the FMKEY register in 4 consecutive instructions. The following
flowchart illustrates the unlock procedure.
START
FMKEY = 0x��;
FMKEY = 0xAA;
FMKEY = 0x00;
FMKEY = 0xFF;
Bit UNLOCK is 1
Fo� example� 4 consec�tive
statements in C lang�age
END
Bit UNLOCK is 0
Flash memo�� is in
locked state
Flash memo�� is in
�nlocked state
Unlock Procedure Flowchart