S3C84E5/C84E9/P84E9

ADDRESS SPACES

 

 

REGISTER PAGE POINTER (PP)

The S3C8-series architecture supports the logical expansion of the physical 512-byte internal register file (using an 8-bit data bus) into as many as 2 separately addressable register pages. Page addressing is controlled by the register page pointer (PP, DFH). In the S3C84E5/C84E9/P84E9 microcontroller, a paged register file expansion is implemented for data registers, and the register page pointer must be changed to address other pages.

After a reset, the page pointer's source value (lower nibble) and the destination value (upper nibble) are always "0000", automatically selecting page 0 as the source and destination page for register addressing.

Register Page Pointer (PP)

DFH ,Set 1, R/W

 

MSB

.7

.6

.5

.4

 

 

 

.3

 

.2

.1

.0

 

LSB

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Destination register page selection bits:

 

Source register page selection bits:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0000

Destination: Page 0

 

 

 

 

 

0000

Source: Page 0

0001

Destination: Page 1

 

 

 

 

 

0001

Source: Page 1

 

 

 

 

 

 

 

 

 

 

 

NOTE:

A hardware reset operation writes the 4-bit destination and source values shown

 

 

above to the register page pointer. These values should be modified to other

pages.

Figure 2-3. Register Page Pointer (PP)

2-5

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Image 40
Samsung S3C84E5 user manual Register page Pointer PP, Msb Lsb