UM10310_1 © NXP B.V. 2008. All rights reserved.
User manual Rev. 01 — 1 December 2008 104 of 139
NXP Semiconductors UM10310
P89LPC9321 User manual
(3)Tabl e 99 shows sample P89LPC9321 timeout values.tclks 2 57+()
()255 1+()1 1048577=+=Table 97. Watchdog Timer Control register (WDCON - address A7h) bit allocation
Bit 76543210
Symbol PRE2 PRE1 PRE0 - - WDRUN WDTOF WDCLK
Reset111xx11/01
Table 98. Watchdog Timer Control register (WDCON - address A7h) bit description
Bit Symbol Description
0 WDCLK Watchdog input clock select. When set, the watchdog oscillator is selected. When cleared, PCLK is
selected. (If the CPU is powered down, the watchdog is disabled if WDCLK = 0, see Section 15.5). (Note: If
both WDTE and WDSE are set to 1, this bit is forced to 1.) Refer to Section 15.3 for details.
1 WDTOF Watchdog Timer Time-Out Flag. This bit is set when the 8-bit down counter underflows. In watchdog mode,
a feed sequence will clear this bit. It can also be cleared by writing a logic 0 to this bit in software.
2 WDRUN Watchdog Run Control. The watchdog timer is started when WDRUN = 1 and stopped when WDRUN = 0.
This bit is forced to 1 (watchdog running) and cannot be cleared to zero if both WDTE and WDSE are set to
1.
3:4 - reserved
5PRE0
Clock Prescaler Tap Select. Refer to Table99 for details.6PRE1
7PRE2
Table 99. Watchdog timeout vales
PRE2 to PRE0 WDL in decimal) Timeout Period
(in watchdog clock
cycles)
Watchdog Clock Source
400KHz Watchdog
Oscillator Clock
(Nominal)
12 MHz CCLK (6 MHz
CCLK⁄2 Watchdog
Clock)
000 0 33 82.5 μs5.50μs
255 8,193 20.5 ms 1.37m s
001 0 65 162.5 μs 10.8 μs
255 16,385 41.0 ms 2.73 ms
010 0 129 322.5 μs 21.5 μs
255 32,769 81.9 ms 5.46 ms
011 0 257 642.5 μs 42.8 μs
255 65,537 163.8 ms 10.9ms
100 0 513 1.28 ms 85.5 μs
255 131,073 327.7 ms 21.8ms
101 0 1,025 2.56 ms 170.8 μs
255 262,145 655.4 ms 43.7ms
110 0 2,049 5.12 ms 341.5 μs
255 524,289 1.31 s 87.4 ms
111 0 4097 10.2 ms 682.8 μs
255 1,048,577 2.62 s 174.8ms