SyncMOS Technologies International, Inc.
SM8958A
8-Bits Micro-controller
With 32KB flash & 1KB RAM embedded
There is a 250KHz RC oscillator embedded in chip. Set WDTE = “1” will enable the RC oscillator and the frequency
is independent to the system frequency.
To enable the WDT is done by setting 1 to the bit 7 (WDTE) of WDTC. After WDTE set to 1, the 16-bit counter starts to
count with the RC oscillator. It will generate a reset signal when overflows. The WDTE bit will be cleared to 0
automatically when SM8958A been reset, either hardware reset or WDT reset.
To reset the WDT is done by setting 1 to the CLEAR bit of WDTC before the counter overflow. This will clear the
content of the 16-bit counter and let the counter re-start to count from the beginning.
3.1 Watch Dog Timer Registers:
Watch Dog Timer Registers - WDT Control Register (WDTC, $9F)
bit-7
bit-0
WDTE
R/W
0
R
-
*
CLEAR
R/W
0
Unused
Unused
PS2
R/W
0
PS1
R/W
0
PS0
R/W
0
Read / Write:
Reset value:
-
*
-
*
WDTE : Watch Dog Timer enable bit
CLEAR : Watch Dog Timer reset bit
PS[2:0] : Overflow period select bits
PS [2:0]
Overflow Period (ms)
2.048
000
001
010
011
100
101
110
111
4.096
8.192
16.384
32.768
65.536
131.072
262.144
Watch Dog Key Register - (WDTKEY, $97H)
bit-7
bit-0
WDT
WDT
WDT
WDT
WDT
WDT
WDT
WDT
KEY7
KEY6
KEY5
KEY4
KEY3
KEY2
KEY1
KEY0
Read / Write:
Reset value:
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
R/W
0
Specifications subject to change without notice contact your sales representatives for the most recent information.
Ver 2.1 SM8958A 08/2006
10
SYNCMOS [ SYNCMOS TECHNOLOGIES,INC ]
