Programming Model

Watchdog Timer Control Register

The watchdog timer control logic in the MC2 chip is used with the "No VMEbus Interface" option. This function is duplicated at the same bit locations in the VMEchip2 at location $FFF40060. The VMEchip2 has the additional option of selecting SYSRESET (i.e., VMEbus reset). It is permissible to enable the watchdog timer in both the VMEchip2 and the MC2 chip.

3

ADR/SIZ

 

 

 

$FFF42044 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

23

22

21

20

19

 

18

17

16

 

 

 

 

 

 

 

 

 

 

NAME

 

WDCS

WDCC

WDTO

WDBFE

 

 

WDRSE

WDEN

 

 

 

 

 

 

 

 

 

 

OPER

R

C

C

R

R/W

 

R

R/W

R/W

 

 

 

 

 

 

 

 

 

 

RESET

0

0 P

0 P

0 P

0 PL

 

0

0 PL

0 PL

 

 

 

 

 

 

 

 

 

 

WDEN When this bit is high, the watchdog timer is enabled. When this bit is low, the watchdog timer is not enabled.

WDRSE When this bit is high, and a watchdog time-out occurs, a LRESET is generated. When this bit is low, a watchdog time-out does not cause a reset.

WDBFE When this bit is high and the watchdog timer has timed out, the MC2 chip asserts the BRDFAIL signal pin. When this bit is low, the watchdog timer does not contribute to the BRDFAIL signal on the MC2 chip.

WDTO When this status bit is high, a watchdog time-out has occurred. When this status bit is low, a watchdog time-out has not occurred. This bit is cleared by writing a one to the WDCS bit in this register.

WDCC When this bit is set high, the watchdog counter is reset. The counter must be reset within the time-out period or a watchdog time-out occurs.

WDCS When this bit is set high, the watchdog time-out status bit (WDTO bit in this register) is cleared.

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Image 231
Motorola MVME172 manual Watchdog Timer Control Register