C8051F360 datasheet(138/288 Pages) SILABS

138 / 288 page

C8051F360/1/2/3/4/5/6/7/8/9

138

Rev. 1.0

13.2. Security Options

The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-

ware as well as to prevent the viewing of proprietary program code and constants. The Program Store

Write Enable (bit PSWE in register PSCTL) and the Program Store Erase Enable (bit PSEE in register

PSCTL) bits protect the Flash memory from accidental modification by software. PSWE must be explicitly

set to ‘1’ before software can modify the Flash memory; both PSWE and PSEE must be set to ‘1’ before

software can erase Flash memory. Additional security features prevent proprietary program code and data

constants from being read or altered across the C2 interface.

A Security Lock Byte located at the last byte of Flash user space offers protection of the Flash program

memory from access (reads, writes, or erases) by unprotected code or the C2 interface. The Flash security

mechanism allows the user to lock n 1024-byte Flash pages, starting at page 0 (addresses 0x0000 to

0x03FF), where n is the 1’s complement number represented by the Security Lock Byte. Note that the

page containing the Flash Security Lock Byte is unlocked when no other Flash pages are locked

(all bits of the Lock Byte are ‘1’) and locked when any other Flash pages are locked (any bit of the

Lock Byte is ‘0’). See the example below for an C8051F360.

Access limit set

according to the Flash

security lock byte

0x0000

0x3FFF

Lock Byte

Reserved

0x3FFE

0x4000

Flash memory organized

in 1024-byte pages

0x3C00

Unlocked Flash Pages

Locked when any

other Flash pages are

locked

0x0000

0x7BFF

Lock Byte

Reserved

0x7BFE

0x7C00

0x7800

Unlocked Flash Pages

‘F360/1/2/3/4/5/6/7

'F368/9

Figure 13.1. Flash Program Memory Map

Security Lock Byte:

11111101b

1’s Complement:

00000010b

Flash pages locked:

3 (First two Flash pages + Lock Byte Page)

Addresses locked:

0x0000 to 0x07FF (first two Flash pages) and

0x7800 to 0x7BFF (Lock Byte Page)

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