Table of Contents
Advertisement
6.4.2 Software Watchdog Timer
The software watchdog timer module has a 3-bit prescaler that is not accessible to users: a
watchdog-compare register (WRR), a read-only 16-bit watchdog counter register (WCN),
and a 4-bit watchdog-control/status register (WCR).
6.4.2.1 WATCHDOG-COMPARE REGISTER. The 16-bit compare register contains the
"compare" value for the watchdog time-out. It appears as a memory-mapped read-write reg-
ister to users.The reset value of the register is $FFFF.
15
14
13
12
Address: $(FF)FFF61A
COMPARE VALUE
When the counter counts up to the value in this register, it generates a system reset . This
register resets to $FFFF. The programmed value in the register will not be affected if the
force-interrupt mode is set in the control register.
6.4.2.2 WATCHDOG COUNTER REGISTER. The watchdog counter register is a 16-bit up-
counter and appears as a memory-mapped register that may be read at any time.
15
14
13
12
Address: $(FF)FFF61C
COUNT
This is the current count value.
A read cycle to the counter register causes the current value of the watchdog timer to be
read. Reading the watchdog timer does not affect the counting operation.
A write cycle to the counter register causes the counter and prescaler to be reset. A write
cycle should be executed on a regular basis so that the watchdog timer is never allowed to
reach the reference value during normal program operation.
6.4.2.3 WATCHDOG-CONTROL/STATUS REGISTER (WCR).
15
14
13
12
Address: $(FF)FFF618
MOTOROLA
MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
11
10
9
COMPARE VALUE
Figure 6-9. Watchdog-Compare Register
11
10
9
Figure 6-10. Watchdog Counter Register
11
10
9
UNUSED
Figure 6-11. Watchdog-Control/Status Register
8
7
6
5
8
7
6
5
COUNT
8
7
6
5
4
3
2
1
Reset Value: $FFFF
4
3
2
1
Reset Value: $0000
4
3
2
1
W/DRST LOCK
FI
Reset Value: $0000
Timer
0
0
0
WDEN
6-7
- Quick Links:
- Key Features
- Mc68328 Architecture
Hide quick links:
Advertisement
Table of Contents
