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GUIDELINES FOR MIGRATING ST72C254 APPLICATIONS TO ST72F264

4.2 REGISTER MODIFICATIONS

4.2.1 CRSR Register

The CRSR (Clock, Reset and Supply Register) register has been replaced by the SICSR

(System Integrity Control/Status Register) register (see Figure 5.). This SICSR register con-

tains the bits related to the AVD feature.

Figure 5. CRSR Register Changes

4.2.2 SPI/SS pin

The SPI SS pin alternate function is controlled from the MISCR2 like previously, but these

control bits have also been duplicated into the SPICSR register in three unused locations.

Figure 6. SS pin control

Both registers can be used to control the SS pin.

SICSR (0025h)

System Integrity Control/Status Register

70

0

AVDI

E

AVD

F

LVD

RF

00

0

WDG

RF

CRSR (0025h)

Clock Reset and Supply Register

70

000

LVD

RF

0

CS-

SIE

CSS

D

WDG

RF

70

0

000

MOD SOD

SSM

SSI

SPICSR (0023h)

SPI Control/Status Register

70

SPIF

WCO

L

OR

MOD

F

0

SOD

SSM

SSI

MISCR2 (0040h)