Bypass and WDT
•
25
5.2 WDT control
5.2.1
WDT control
Four signals, which are the GPIO pins of the PCI-to-PCI chip, control
the WDT. The function names are listed as the following table:
Functions
Default Action command
GPIO0
Enable WDT
H
GPIO1
Disable WDT
H
GPIO2
Reload WDT
H
GPIO3
Force to Normal State
H
The power up status of those control signals are set as “input” pins
therefore the default logic is pulled high. To enable, disable or reload
the WDT, the program must set those bits to low then high to generate
the rising edge trigger. If the reload of WDT value is larger than time
out value, then the communication state will switch to
Bypass State
automatically. The GPIO3 pin is effective only if
JP4~7
setting
Default
State
to
Bypass State
.
5.2.2
WDT Time-out Value
The WDT time-out value is switch selectable by a 4-status switch SW1.
The time out value is selectable as 1, 2, 4, or 8 seconds.
1
4
3
2
N
O
SW1
Time out value = 1 second
1
4
3
2
N
O
SW1
1
4
3
2
N
O
SW1
1
4
3
2
N
O
SW1
Time out value = 2 second
Time out value = 4 second
Time out value = 8 second
Содержание PCI-8213
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