XC2000 datasheet(104/647 Pages) INFINEON

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XC2000 Derivatives

System Units (Vol. 1 of 2)

Memory Organization

Preliminary

User’s Manual

3-42

V1.0, 2007-06

MemoryX2K, V1.1

To summarize:

•

Read protection is always globally affecting the whole flash memory range. Code

fetches and data reads can be separately controlled.

•

Write protection can be global when the read protection is effective or it can be

specific for each logical sector.

The lower and the middle security layers determine how the 4 effective IMB_IMBCTR

fields are preset, changed and how software can access them. This is discussed in the

following paragraphs.

Initialization of the Effective Security Level

After Application Reset protection is activated so that RPA, WPA, DDF and DCF are set.

During startup the IMB Core determines the stored security level as described in “The

Lower Layer “Physical State”” on Page 3-39 and sets IMB_FSR.PROIN and

IMB_FSR.PROINER and IMB_PROCONx as described in “The Middle Layer “Flash

State”” on Page 3-39. The IMB Core further initializes the IMB_IMBCTR fields RPA and

WPA according to the rules of Table 3-4.

The bits DDF and DCF of the IMB_IMBCTR are not initialized by the IMB Core. During

system startup they are initialized depending on the startup condition. If code fetching

starts in the flash memory then they are set to the inactive state. In all other cases they

are activated to prevent read access to the flash memory without proving password

knowledge.

Changing the Effective Security Level

During run-time the effective security level can be changed. This can be done by directly

writing to the IMB_IMBCTR register or indirectly by changing the bits of the middle layer

by commands as “Disable Write Protection” or even double indirectly by changing the

content of the security pages which changes bits in the middle layer and influences the

effective security level.

Writing directly to IMB_IMBCTR:

•

DCF and DDF can be deactivated only if RPA is inactive. They can always be

activated.

Indirectly by using a command sequence:

•

A successful “Disable Read Protection” sets RPRODIS and clears RPA.

1 | #

Global write protection.

1 | #

Sector specific write protection depending on

IMB_PROCONx.

Table 3-6

Effective Write Security (cont’d)

WPA

RPA

Security Level

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