Z8 Encore! XP
®
4K Series
Product Specification
87
WDTUNLK—Watch-Dog Timer Unlock
The user software must write the correct unlocking sequence to this register before it is
allowed to modify the contents of the watch-dog timer reload registers.
Watch-Dog Timer Reload Upper, High and Low Byte Registers
The Watch-Dog Timer Reload Upper, High and Low Byte (WDTU, WDTH, WDTL) reg-
isters (Tables
form the 24-bit reload value that is loaded into the Watch-
Dog Timer when a WDT instruction executes. The 24-bit reload value is {WDTU[7:0],
WDTH[7:0], WDTL[7:0]}. Writing to these registers sets the appropriate Reload Value.
Reading from these registers returns the current Watch-Dog Timer count value.
Caution:
The 24-bit WDT Reload Value must not be set to a value less than
000004H
.
Table 59. Watch-Dog Timer Reload Upper Byte Register (WDTU)
BITS
FIELD
RESET
R/W
ADDR
7
6
5
4
WDTU
FFH
R/W*
FF1H
3
2
1
0
R/W* - Read returns the current WDT count value. Write sets the appropriate Reload Value.
WDTU—WDT Reload Upper Byte
Most significant byte (MSB), Bits[23:16], of the 24-bit WDT reload value.
Table 60. Watch-Dog Timer Reload High Byte Register (WDTH)
BITS
FIELD
RESET
R/W
ADDR
7
6
5
4
WDTH
FFH
R/W*
FF2H
3
2
1
0
R/W* - Read returns the current WDT count value. Write sets the appropriate Reload Value.
WDTH—WDT Reload High Byte
Middle byte, Bits[15:8], of the 24-bit WDT reload value.
PS022815-0206
Watch-Dog Timer
ZILOG [ ZILOG, INC. ]
