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LH75400/01/10/11 (Preliminary) User’s Guide
Watchdog Timer
6/17/03
16-3
16.3.1 WDT Register Definitions
16.3.1.1 Control Register
CTRL is the Control Register. The active bits used in this register are Read/Write.
Table 16-2. CTRL Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
TOP
FRZ
///
RSP
EN
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
R
R
R
R
R
R
R
R
RW
RW
RW
RW
RW
R
RW
RW
ADDR
0xFF 0x00
Table 16-3. CTRL Register Definitions
BITS NAME
DESCRIPTION
31:8
///
Reserved
Writing to these bits has no effect. Reading returns 0.
7:4
TOP
Time Out Period
Selects 1 of 16 possible values to load into the counter to de-
termine the time-out period. Example: 0x0 = 2
16
, 0xF = 2
31
HCLK cycles. When
setting or changing the time-out period, the new value will not come into affect un-
til a counter-reset command has been issued or when the WDT times out.
3
FRZ
Freeze EN Bit (set-only)
0 = Do not stop the EN bit from being cleared when the watchdog is enabled.
1 = Stop the EN bit from being cleared when the watchdog is enabled. This
avoids accidental write operations that disable the watchdog, and can only be
cleared by a System Reset.
2
///
Reserved
Writing to these bits has no effect. Reading returns 0.
1
RSP
Time-out Response
Determines the output response on a time-out period.
0 = Only a System Reset is generated on a time-out period.
1 = An interrupt is generated on the first time-out period. If this is not cleared, a
System Reset is generated on the second time-out period.
0
EN
Watchdog Enable/Disable
0 = Watchdog disabled. Counter does not decrement, and no interrupts or
System Resets will be generated by the watchdog.
1 = Watchdog enabled. Allows the counter to decrement, causing interrupts to be
generated if the count is not periodically reset to stop the count value from
reaching zero.