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Java Terminals Hardware Interface Description
8 Appendix A: (Hardware) Watchdog
69
EHSxT_BGS5T_HID_v02
2014-05-23
Confidential / Preliminary
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8
Appendix A: (Hardware) Watchdog
The watchdog is part of the Java Terminals and connected to the Java module itself (see also
). It can be used to
•
Safely reset the module in certain conditions
•
Restart the module when it has turned off
•
Configure GPIOs and DSR0/ADC1_IN available at the Weidmueller connector
The complete watchdog functionality can be configured via the serial interface ASC0 (for de-
tails see
). Some configuration commands can also be specified via I
2
C interface
(for details see
).
shows how the watchdog may be accessed.
Figure 17:
Hardware watchdog
8.1
Reset Conditions
The watchdog implements three conditions, under which a reset of the module is automatically
performed:
•
Repetitive: A module reset is performed frequently and repetitive. This reset condition can
be used to force the module to reconnect to the mobile network once in a while. Typical fre-
quencies are 24 hours or more. This feature can be configured via the RST_REP timeout.
•
UART activity: The watchdog can be used to reset the module, when no activity from the
module on the UART interface is recognized for a specified amount of time. To prevent the
reset, the module has to be active frequently on the UART interface. This reset condition
can be configured via the RST_UART timeout, it is deactivated when timeout parameter = 0.
•
GPIO activity: The watchdog can be used to reset the module, when no activity on the des-
ignated GPIO signal is recognized for a specified amount of time. To prevent the reset, the
module has to be active frequently by toggling this GPIO signal. This reset condition can be
configured via the RST_GPIO timeout, it is deactivated when timeout parameter = 0.
When the watchdog is enabled, it will observe the activities on the UART and GPIO interfaces,
depending on timeout parameter setting and perform frequent resets, if it is configured to do so.
Hardware watchdog
Resets/Restarts the Java
module under certain
conditions and
configures GPIOs
RS-232
connector
Weidmueller
connector
Java module
TXD0 line (ASC0 with
baud rate = 1200bps) for
watchdog configuration
I
2
C interface lines or RS-485
lines (with RS-232-to-RS-485
adapter) for watchdog
configuration
ASC0 interface (baud rate not equal 1200bps) for watchdog configuration via I
2
C command
AT^SSPI for
watchdog onfiguration
Java Terminal
