Cinterion
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Java Terminals Hardware Interface Description
8.3 Configuration via ASC0 Interface
69
EHSxT_BGS5T_HID_v02 2014-05-23
Confidential / Preliminary
Page 56 of 70
8.3 Configuration via ASC0 Interface
The complete hardware watchdog functionality can be configured via the serial interface ASC0
as described in this section.
The watchdog listens on the module's TXD0 line exclusively at the low baudrate 1200bps, and
gives no feedback. This means that if using the watchdog this low baud rate is reserved and
should not be configured for the module‘s asynchronous serial interface ASC0. The TXD0 line
can be accessed either via RS-232 interface or via RS-485 interface (in conjunction with an
RS232-to-RS485 adapter).
So, to control and configure the watchdog, a terminal program MUST be set to 1200bps, before
a command (see Section 8.3.1) can be sent to the watchdog. Once completed, the terminal
program should be changed to higher baud rates again to enable proper communication with
the module.
Please note that some configuration commands can also be configured via I
2
C interface (see
Section 8.4 for details).
8.3.1 Command Specification
The general watchdog command syntax is as follows:
WD=<command>,<argument>,<checksum><NL>
Where
• <command> specifies the command name
•
<argument> gives the numeric argument
• <checksum> is the sum of the digits of the argument. (e.g. the argument 124 produces a
checksum 7, because 1+2+4=7).
Whenever a non-volatile command is executed, it is saved in the watchdog's flash memory. At
watchdog start, the last state is loaded from flash memory.
If a config command was successfully executed by the watchdog, the green ON led flashes two
times. The watchdog commands are implemented as text commands. In case a command error
occours - e.g., a checksum failure - the green ON led flashes 4 times.
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