Appendix a: programming watchdog timer, Appendix a, Programming watchdog timer – Lanner LEC-3012 User Manual

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Programming Watchdog Timer

Embedded and Industrial Computing

Appendix A

Appendix A:

Programming Watchdog

Timer

A watchdog timer is a piece of hardware that can be used

to automatically detect system anomalies and reset the

system (or one pair of network ports in bypassed state;

However, only one function can be activated at a time.)

in case there are any problems. Generally speaking, a

watchdog timer is based on a counter that counts down

from an initial value to zero. The software selects the

counter’s initial value and periodically restarts it. Should

the counter reach zero before the software restarts it,

the software is presumed to be malfunctioning and the

processor’s reset signal is asserted. Thus, the processor

will be restarted as if a human operator had cycled the

power.
For sample watchdog code, see wd_bp folder under Driver

and Utility on the Driver and Manual CD

Executing the commands through the Command Line:
1. wd_tst --swtsr (Set Watchdog Timeout State to Reset)
2. wd_tst --swt xxx (Set Watchdog Timer 1-255 seconds)
3. wd_tst[*] --start (Start Watchdog Timer)
4. wd_tst --stop (Stop Watchdog Timer)
The following procedures are required for running the

watchdog program on DOS, Linux and FreeBSD.

Note:

For DOS environment, use DJGPP as compiler

and the makefile: Makefile.dos.

For Linux, support kernel versions are 2.4.x and

2.6.x. Use the makefile:Makefile.linux.

For FreeBSD, support version is FreeBSD 8.0.

Use the makefile: Makefile.

Build

To build program source code on Linux platform, use the

following steps as a guideline:

Copy the proper makefile from the Driver and Manual

CD to your system

Set the access mode with these two parameters

by editing the Makefile.linux directly: DIRECT_IO_

ACCESS= [0|1] (enter either 1 or 0) and LANNER_

DRIVER= [0|1] (enter either 1 or 0). 1 is for direct access

and no driver is needed. You will only need to execute

the program directly. However, when it equaled to 0,

driver installation is needed. Refer to the following

Install section for more details.
Type make to build source code:

3.
make Makefile (Note: omit the file extensions)
After compiled, the executable program (bpwd_tst) and

the driver (bpwd_drv.ko) will be in the bin subdirectory.

Install

The installation procedures depend on the access mode

that you have set by using the above mentioned method.
If you have set DIRECT_IO_ACCESS=1, driver installation is

not necessary. Proceed to the next section on execute
If you have set DIRECT_IO_ACCESS=0, Lanner driver needs

to be installed. Install the driver and create a node in the /

dev directory as shown in the following example:
For Linux:
Insert module and create node in /dev as below

example:
#insmod wd_drv.[k]o
#mknod /dev/wd_drv c 241 0

For FreeBSD:
Insert module as below example:
#kldload -v ./wd_drv.ko

Execute

# wd_tst --swtsr (Set Watchdog Timeout State to reset

function)
# wd_tst --swtsr (Set Watchdog Timeout State to Reset

function)
# wd_tst --swt xxx (Set Watchdog Timer 1-255 seconds)
# wd_tst[*] --start (Start Watchdog Timer)
# wd_tst --stop (Stop Watchdog Timer)

Note:

wd_tst --start will not be available if

DIRECT_IO_ACCESS=1, use the command: “./