PCF2129AT NXP [NXP Semiconductors], PCF2129AT Datasheet - Page 29

• Manufacturer Part Number: PCF2129AT
• Description: Integrated RTC, TCXO and quartz crystal
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
PCF2129A_1
Product data sheet
8.10.1 Register Watchdg_tim_ctl
8.10.2 Register Watchdg_tim_val
8.10 Timer functions
The PCF2129A has a watchdog timer function. The timer can be selected by using the
control bit WD_CD in the register Watchdg_tim_ctl.
The watchdog timer has four selectable source clocks. It can be used to detect a
microprocessor with interrupt and reset capability which is out of control (see
Section
To control the timer function and timer output, the registers Control_2, Watchdg_tim_ctl,
and Watchdg_tim_val are used.
Table 30.
[1]
[2]
Table 31.
Bit
7
6
5
4 to 2
1 to 0 TF[1:0]
Bit
7 to 0 WATCHDG_TIM_VAL[7:0]
Default value.
When writing to the register this bit has always to be set logic 0.
Symbol
WD_CD
T
TI_TP
Symbol
8.10.3)
Watchdg_tim_ctl - watchdog timer control register (address 10h) bit description
Watchdg_tim_val - watchdog timer value register (address 11h) bit description
Rev. 01 — 13 January 2010
Value
0
1
0
0
1
-
00
01
10
11
[1]
[2]
[1]
[1]
Value
00 to FF countdown period in seconds:
Description
watchdog timer disabled
watchdog timer enabled;
unused
the interrupt pin INT is configured to generate a
permanent active signal when MSF (register Control_2)
is set
the interrupt pin INT is configured to generate a pulsed
signal when MSF flag is set (see
unused
timer source clock for watchdog timer
the interrupt pin INT is activated when timed out
4.096 kHz
64 Hz
1 Hz
1
⁄
60
Hz
Description
where n is the countdown value
CountdownPeriod
Integrated RTC, TCXO and quartz crystal
=
-------------------------------------------------------------- -
SourceClockFrequency
PCF2129A
Figure
© NXP B.V. 2010. All rights reserved.
19)
n
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