
S3C8248/C8245/P8245/C8247/C8249/P8249
ADDRESS SPACES
2-5
REGISTER PAGE POINTER (PP)
The S3C8-series architecture supports the logical expansion of the physical 256-byte internal register file (using
an 8-bit data bus) into as many as 16 separately addressable register pages. Page addressing is controlled by the
register page pointer (PP, DFH). In the S3C8248/C8245/C8247/C8249 microcontroller, a paged register file
expansion is implemented for LCD 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
LSB
MSB
.7
.6
.5
.4
.3
.2
.1
.0
Destination register page selection bits:
0000
Destination: Page 0
Source register page selection bits:
0000
Source: Page 0
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 address other pages.
Figure 2-3. Register Page Pointer (PP)
+
+
PROGRAMMING TIP — Using the Page Pointer for RAM clear (Page 0, Page 1)
LD
PP,#00H
; Destination
←
0, Source
←
0
SRP
#0C0H
LD
R0,#0FFH
; Page 0 RAM clear starts
RAMCL0
CLR
@R0
DJNZ
R0,RAMCL0
CLR
@R0
; R0 = 00H
LD
PP,#10H
; Destination
←
1, Source
←
0
LD
R0,#0FFH
; Page 1 RAM clear starts
RAMCL1
CLR
@R0
DJNZ
R0,RAMCL1
CLR
@R0
; R0 = 00H
NOTE:
You should refer to page 6-39 and use DJNZ instruction properly when DJNZ instruction is used in your program.
Содержание S3C8248
Страница 31: ...ADDRESS SPACES S3C8248 C8245 P8245 C8247 C8249 P8249 2 20 NOTES ...
Страница 107: ...INTERRUPT STRUCTURE S3C8248 C8245 P8245 C8247 C8249 P8249 5 18 NOTES ...
Страница 195: ...INSTRUCTION SET S3C8248 C8245 P8245 C8247 C8249 P8249 6 88 NOTES ...
Страница 221: ...I O PORTS S3C8248 C8245 P8245 C8247 C8249 P8249 9 16 NOTES ...
Страница 245: ...16 BIT TIMER 0 1 S3C8248 C8245 P8245 C8247 C8249 P8249 12 10 NOTES ...
Страница 249: ...WATCH TIMER S3C8248 C8245 P8245 C8247 C8249 P8249 13 4 NOTES ...
Страница 267: ...A D CONVERTER S3C8248 C8245 P8245 C8247 C8249 P8249 15 6 NOTES ...
Страница 299: ...S3P8245 P8249 OTP S3C8248 C8245 P8245 C8247 C8249 P8249 21 8 NOTES ...
Страница 307: ......
Страница 309: ......
Страница 311: ......
Страница 313: ......
Страница 315: ...BOOK SPINE TEXT SAMSUNG Logo S3C8248 C8245 P8245 C8247 C8249 P8249 Microcontrollers User s Manual Rev 3 March 2002 ...