PMCDIO64
Copyright
2000 BVM Ltd.
15
7.3.7
Watchdog Trigger Register
The 8-bit read/write Watchdog Trigger Register must be written to with bit 0 set to 0 and 1 alternately
within
±
25% of the watchdog refresh time when the watchdog function is enabled in the Status &
Control Register - see section "7.3.6 Status & Control Register (on page 14)".
7.3.8
Watchdog Timer Register
The 8-bit read/write Watchdog Timer Register is used to set the refresh period. The watchdog timer
runs from its own independent 32.768kHz oscillator and has a programmable refresh period between
125ms and 2sec. On reset the watchdog is not running and has a refresh period of 125ms. The
watchdog timer is started by the first write to the watchdog trigger register. Bits 2 - 0 set the refresh
period, bits 7 - 3 are undefined on a read and should be written as zero for future compatibility.
Note that once the internal watchdog is running, this register is read only - writing to the register will
cause the watchdog to trigger.
Bits
2 - 0
Watchdog Refresh Period
0
125ms
1
250ms
2
500ms
3
1.0sec
4
2.0sec
5
2.0sec
6
2.0sec
7
2.0sec
7.3.9
Watchdog Status Register
The 8-bit read only Watchdog Status Register is used to determine the status of the watchdog. When
bit 0 is read as 1 the watchdog function is enabled, when bit 1 is read as 1 the watchdog function has
been started, bits 7 - 2 are undefined when read.
Note that writing to this register whilst the internal watchdog is running will cause the watchdog to
trigger.
Bits
1 - 0
Watchdog Status
0
Not Started
1
Illegal State
2
Tripped
3
Running
7.4 Interrupts
PCI INTA# is generated when a change-of-state occurs after being enabled or a watchdog time-out
occurs after the watchdog is enabled. The interrupt will be removed when the change flags are cleared
- see section "7.3.6.8 Interrupt On Change-of-State Status (Bit 15: IOCST) (on page 14)" and when
the watchdog interrupt is disabled - see section "7.3.6.1 Watchdog Interrupt Enable (Bit 3: WINEN) (on
page 14)".
7.5 Windows
®
Driver Disc
BVM can supply a disc containing the driver files and example source code for Windows
®
98, NT4.0
and 2000 along with BVM installation files. The BVM installation files will ensure that the correct driver
configuration is selected upon installation.
