C: w, Ppendix, Atchdog – NEXCOM NISE 101 User Manual

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NISE 101 User Manual

Appendix C: Watchdog Timer Setting

ppendix

C: W

AtChdog

imer

etting

The NISB101’s onboard watchdog timer uses an 8-bit counter; therefore it
has 256 resolution and the time range is from 1 to 255 seconds with a
resolution of per second or 1 to 255 minutes with a resolution of per
minute.

When the timer is setting and time-out occurs, it will trigger the hardware
reset signal and a system reset will happen.

The NISB101’s onboard watchdog timer function is carried out by the
ITE IT8712F I/O chip. If you want to use this function in your program, you
have to know how to read/write the IT8712F configuration register. The
onboard IT8712F I/O chip’s decode address is 02Eh, its index port and data
port is 02Fh. The read/write register methods are write register number to
index port, then read/write data from/to data port.

The following describes how to program the IT8712F register and the
procedure of using watchdog function.

To program the IT8712F register:

1. Unlock the IT8712F I/O chip and enter the configuration mode.

2. Select Logical Device.

3. Select the register number.

4. Read/Write data from/to register.

5. Lock the IT8712F I/O chip and exit from the configuration mode.

To Unlock/Lock IT8712F and Enter/Exit the configuration mode is to write a
specific value to I/O Port 02Eh.

Unlock IT8712F: contiue write value 87h, 01h, 55h, 55h to I/O port 02Eh.
Lock IT8712F: write value 02h to I/O port 02Fh.

Program watchdog procedure:

1. Unlock the IT8712F I/O chip and enter the configuration mode.

write unlock value (87h,01h,55h,55h) to port 02Eh

ex: outportb(0x2E, 0x87);

outportb(0x2E, 0x01);

outportb(0x2E, 0x55);

2. Select the logical device to 7

write value (07h) to register number 07h

ex: outportb(0x02E, 0x07);

outportb(0x02F, 0x07);