SM89516 Datasheet, PDF (7/19 Pages) SyncMOS Technologies,Inc – 8-Bits Micro-controller With 64KB flash & 1KB RAM embedded

SyncMOS Technologies International, Inc.
Internal RAM Control Register (RCON, $85)
SM89516
8-Bits Micro-controller
With 64KB flash & 1KB RAM embedded
Read / Write:
Reset value:
bit-7
bit-0
Unused
-
*
Unused
-
*
Unused
-
*
Unused
-
*
Unused
-
*
Unused
-
*
RAMS1
R/W
0
RAMS0
R/W
0
SM89516A has 768 byte on-chip RAM which can be accessed by external memory addressing method only. (By
instruction MOVX). The address space of instruction MOVX @Rn is determined by bit 1 and bit 0 (RAMS1, RAMS0)
of RCON. The default setting of RAMS1, RAMS0 bits is 00 (page0).
RAMS1
0
0
1
RAMS0
0
1
0
MOVX @Ri i=0,1 mapping to expended RAM address
$0000 ~ $00FF
$0100 ~ $01FF
$0200 ~ $02FF
The port 0, port2, port3.6 and port3.7 can be used as general purpose I/O pin while port0 is open-drain structure.
System Control Register (SCONF, $BF)
bit-7
bit-0
Read / Write:
Reset value:
WDR
R/W
0
Unused
-
*
Unused
-
*
Unused
-
*
Unused
-
*
Unused
-
*
OME
R/W
1
ALEI
R/W
0
WDR: Watch Dog Timer Reset. When system reset by Watch Dog Timer overflow, WDR will be set to 1
OME: 768 bytes on-chip RAM enable bit
ALEI: ALE output inhibit bit, to reduce EMI
The bit 7(WDR) of SCONF is Watch Dog Timer Reset bit. It will be set to 1 when reset signal generated
by WDT overflow. User should check WDR bit whenever un-predicted reset happened.
1.3 I/O Pin Configuration
The ports 1, 2 and 3 of standard 8051 have internal pull-up resistor, and port 0 has open-drain outputs. Each I/O pin
can be used independently as an input or an output. For I/O ports to be used as an input pin, the port bit latch must
contain a ‘1’ which turns off the output driver FET. Then for port 1, 2 and 3 port pin is pulled high by a weak internal
pull-up, and can be pulled low by an external source. The port 0 has open-drain outputs which means its pull-ups are
not active during normal port operation. Writing ‘1’ to the port 0 bit latch will causing bit floating so that it can be used as
a high-impedance input.
The port 4 used as GPIO will has the same function as port 1, 2 and 3.
Specifications subject to change without notice contact your sales representatives for the most recent information.
Ver 2.1 SM89516 08/2006
7