User`s manual

ENDAT-2794A USERS MANUAL

UNICORN COMPUTER CORP.

2-4. Watch Dog Timer

Watch dog Timer (WDT) is a special design for system monitoring to secure the

system work normally. WDT has an independent clock from the oscillator and could

set time and clear/refresh WDT counter function. When time is up, WDT will send

hardware RESET signal to reset system.

Timeout Value Range

-1 to 255

-Second or Minute

Sample code (using TurboC/C++ 3.0):

2-5. Digital I/O

Pin define:

J5: DIGITAL I/O Pin Header (2 x 7 with 2.0mm)

Pin No. Function Pin No. Function

1 +5V 2 +5V

3 DIO-O0 4 DIO-I0

5 DIO-O1 6 DIO-I1

7 GND 8 GND

9 DIO-O2 10 DIO-I2

11 DIO-O3 12 DIO-I3

13 +3.3V 14 +3.3V

Voltage tolerance: +/- 5% with 0V to +5V.

outportb(0x4e,0x87); //Unlock register

outportb(0x4e,0x07); //Set Logic Device number pointer

outportb(0x4f,0x07); //Set Logic Device number

outportb(0x4e,0xF5);

outportb(0x4f,0x40);

outportb(0x4e,0xF6);

outportb(0x4f,0x00);//0-7 Bit :Time out value for watch dog timer

outportb(0x4e,0xF5);

outportb(0x4f,0x20);//Bit 5:If this bit is set to 1, the counting of watch dog time is enabled (bit

1:0 are select output pulse width of RESET signal: 0 for 1 ms, 1 for 25 ms, 2 for 125ms and 3 for

5 seconds)