AS8267 datasheet(83/136 Pages) AMSCO

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Data Sheet AS8267 / AS8268

Revision 1.0, 19-Jun-07

Page 83 of 136

8.7

FLASH Memory

The AS8267 / AS8268 provide a 32kByte Flash Memory for program and data. This Flash is organised in 512

pages with 64Bytes each. When the memory is erased all bytes are 0x00.

To speed up writing to the Flash Memory, a page write mode is available. A page program writes the data in the addressed

memory page. It is also possible to write parts of a page or a single byte. Data that has not been addressed

remains unchanged. Before data can be written to the memory, the addressed page or the whole memory must

be erased. A mass erase sets all bit cells in the memory to logic ‘0’. A page erase sets all bit cells of an

addressed page to logic ‘0’.

The Flash memory can be accessed via System Control in UART1 or the SPI_Flash commands.

FLASH Registers

Address

Reset Value

Note

FLASH_STAT

9700h

0rra.0000

FLASH_ATTACK

9701h

000s.ssss

Note:

rr and s.ssss status bits are copied from Flash memory during boot sequence

‘a‘ is dependent of LOCK bit after reset. If LOCK bit is set then ‘a‘ becomes 0 (access denied) otherwise ‘a‘ becomes 1

and access is granted.

FLASH Status Register

MSB

LSB

CPU_PE

LOCK

ATK_EN

ACCESS_EN

REQ

WEL

WIP

Bit

Symbol

Function

CPU_PE

CPU page erase, triggers a page erase process of the Flash on next CPU write access.

Must be cleared by CPU afterwards (Not to be used by UART1) (read/write)

LOCK

Locks the Flash memory against unauthorized read access from outside using

SET_PW(f7h) or SET_PW1(f8h) command via UART1. Stored in Flash memory (non-

volatile) (read only)

ATK_EN

Enables the attack counter using SET_PW1 (f8h) command via UART1. Stored in Flash

memory (non-volatile) (read only)

ACCESS_EN Grant access to Flash if password entered correctly (read only)

Not used

REQ

External Flash Request (Not to be used by CPU due to dead lock!) (read/write)

WEL

Write enable latch (only writeable by SPI “WREN” command)

WIP

Write in progress (read only)

Note:

The WIP bit is set as soon as a Write, Page Erase or Mass Erase command is sent and reset when the Flash is ready again.

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