SM8958B Datasheet, PDF (18/49 Pages) SyncMOS Technologies,Inc – 256 bytes SRAM as standard 8052

SM8958B
8-Bit Micro-controller
32KB Flash
& 1KB RAM embedded
3.2 Data Memory
The SM8958B has 256B +768B on-chip SRAM. 256B of it are the same as general 8052 internal memory structure
while the expanded 768 Bytes on-chip SRAM can be accessed by external memory addressing method ( by
instruction MOVX). As shown in Fig. 3-2.
02FF
FF
FF
Higher 128 Bytes (Accessed by SFR (Accessed by direct addressing
indirect addressing mode only)
mode only)
80
80
7F
Lower 128 Bytes (Accessed by
direct & indirect addressing mode )
00
Fig. 3-2: RAM architecture
Expanded 768 Bytes
(Accessed by direct
external addressing mode
by instruction MOVX)
0000
3.3 Data memory - lower 128 byte (00h to 7Fh)
Data memory 00h to FFh is the same as 8052.
The address 00h to 7Fh can be accessed by direct and indirect addressing modes.
Address 00h to 1Fh is register area.
Address 20h to 2Fh is memory bit area.
Address 30h to 7Fh is for general memory area.
3.4 Data memory - higher 128 byte (80h to FFh)
The address 80h to FFh can be accessed by indirect addressing mode.
Address 80h to FFh is data area.
3.5 Data memory - Expanded 768 bytes ($0000 to $02FF)
From external address 0000h to 02FFh is the on-chip expanded SRAM area, total 768 Bytes. This area can be
accessed by external direct addressing mode (by instruction MOVX).
Mnemonic Description Dir. Bit 7
SCONF
RCON
DBANK
System
Configuration
BFh
Register
Internal RAM
Control Register
85h
Data Bank
Control Register
86h
WDR
-
BSE
Bit 6 Bit 5 Bit 4
Expanded RAM
-
-
PDWU
E
Bit 3
-
-
-
-
-
-
-
-
BS3
Bit 2 Bit 1 Bit 0 RST
-
OME ALEI 02H
-
RAMS
1
RAMS
0
00H
BS2 BS1 BS0 01H
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M085
Ver D SM8958B 08/07/2015
- 18 -