z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 102

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Table 56. Watchdog Timer Control Register (WDTCTL)
Watchdog Timer Control Register Definitions
BITS
FIELD
RESET
R/W
ADDR
PS026308-1207
Caution:
Watchdog Timer Control Register
Watchdog Timer Reload Upper, High, and Low Byte Registers
W
7
X
occurs, the lock state machine resets and no further writes occurs unless the sequence is
restarted. The value in the Watchdog Timer reload registers is loaded into the counter
when the Watchdog Timer is first enabled and every time a WDT instruction is executed.
The Watchdog Timer control (WDTCTL) register is a write-only control register. Writing
the unlock sequence:
Watchdog Timer reload byte registers (WDTU, WDTH, and WDTL) to allow changes to
the time-out period. These Write operations to the WDTCTL register address have no
effect on the bits in the WDTCTL register. The locking mechanism prevents spurious
writes to the reload registers.
This register address is shared with the read-only reset status register.
WDTUNLK—Watchdog Timer unlock
The user software must write the correct unlocking sequence to this register before it is
allowed to modify the contents of the Watchdog Timer reload registers.
The Watchdog Timer reload upper, high and low byte (WDTU, WDTH, WDTL) registers
(Table 57
WDTH[7:0], WDTL[7:0]} that is loaded into the Watchdog Timer, when a WDT
instruction is executed. Writing to these registers sets the appropriate reload value.
Reading from these registers returns the current Watchdog Timer count value.
The 24-bit WDT reload value must not be set to a value less than
through
W
X
6
Table 59
55H
W
X
5
,
AAH
on page 91) form the 24-bit reload value{WDTU[7:0],
to the WDTCTL register address unlocks the three
W
X
4
WDTUNLK
FF0H
W
X
3
Z8 Encore!
W
X
2
Product Specification
W
X
1
®
000004H
F083A Series
Watchdog Timer
.
W
X
0
90