FabiaTech FB2710, User Manual

Page: 72 / 85

FabiaTech Corporation
‰
Watchdog Timer Enabled
To enable the watchdog timer, you have to output a byte of timer factor to the
watchdog register whose address is 2eh and data port is 2fH. The following is a
Demo program, which demonstrates how to enable the watchdog timer and set
the time-out period at 28 seconds.
;------------------------------------------------------------------------------------------
; Enter the extended function mode
;------------------------------------------------------------------------------------------
outportb (0x2e,0x87); // Enter to extended function mode
outportb(0x2e,0x01);
outportb(0x2e,0x55);
outportb(0x2e,0x55);
;--------------------------------------------------------------------------------------------------------------
; Logical device 7, configuration registers Index 72h-Bit 7, 73H (LSB)/74H (MSB)
;--------------------------------------------------------------------------------------------------------------
outportb(0x2e,0x72); // Index 72h- Time and Watchdog Register
outportb(0x2f,0x90); // Set Bit 7 is 1: Second and Bit4: Enabled Watchdog.
//outportb(0x2f,0x10); // Set Bit 7 is 0: Minute.
outportb(0x2e,0x74); // Set Timer Value counter1 0100~FF00 (MSB)
outportb(0x2f,0x00);
outportb(0x2e,0x73);
// Set Timer Value counter0 0001~00FF (LSB)
outportb(0x2f,0x28); // Set timeout interval as 28seconds and start counting
;------------------------------------------------------------------------------------------
; Exit the extended function mode
;------------------------------------------------------------------------------------------
outportb(0x2e,0x02);
outportb(0x2f,0x02);
‰
Watchdog Timer Trigger
After you enable the watchdog timer, your program must write the same factor as
enabling to the watchdog register at least once every time-out period to its
previous setting. You can change the time-out period by writing another timer
factor to the watchdog register at any time, and you must trigger the watchdog
before the new time-out period in next trigger.
‰
Watchdog Timer Disabled
To disable the watchdog timer, simply write a 00H to the watchdog register.
;--------------------------------------------------------------------------------------------------------------
; Logical device 7, configuration registers Index 72h Bit 4
;--------------------------------------------------------------------------------------------------------------
outportb(0x2e,0x72);
// Index 72h- Time and Watchdog Register
outportb(0x2f,0x00); // Set Bit4 to 0 Disabled Watchdog.
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