Watchdog 0 And 1 Control Register; Watchdog 0 And 1 Preset Register - GE SBC330 3U VPX Hardware Reference Manual

66 SBC330 3U VPX Single Board Computer
The Watchdog Timer can be extended to generate an interrupt at a given value by
setting the Watchdog Interrupt Value register to a value smaller than the preset
value. Setting a higher value than the preset will never generate an interrupt. This
is useful for informing a user that the system is about to reset. For instance, if a
slow clock and the maximum preset value is selected such that the Watchdog
expires after 52.4 seconds and the normal software is set to service the Watchdog
every
40 seconds, the Watchdog Interrupt Register can be set so that the CPU can issue a
warning to the user that the system will reset in 5 seconds.
The interrupt occurrence is calculated as follows:
(Watchdog timer period – Watchdog interrupt) * clock period
NOTE
The Watchdog interrupt is not yet implemented.

6.16.1 Watchdog 0 and 1 control register

Chip Select CS2
Offset 0x0090 (Watchdog 0)
0x0098 (Watchdog 1)
LAD Bit Reg Bit R/W
15 0 R
14 1 R
13 2 R
12 3 R/W
11 & 10 4 & 5 R/W
9 & 8 6 & 7 R/W

6.16.2 Watchdog 0 and 1 preset register

Chip Select CS2
Offset 0x0094 (Watchdog 0)
0x009C (Watchdog 1)
LAD Bit Reg Bit R/W
15 to 0 0 to 15 R/W
Description
Watchdog status
0 = Watchdog enabled
1 = Watchdog disabled
Watchdog expired
0 = Watchdog not expired
1 = Watchdog expired
Watchdog Interrupt
0 = Watchdog interrupt inactive
1 = Watchdog interrupt active
Fast or Slow Clock Select
0 = Slow clock
1 = Fast clock
Stop & Clear
Write '01' followed by '10' to
service the Watchdog
Run & Load
Write '01' followed by '10' to start
the Watchdog
Description
Watchdog preset value: 0 to 65535
Reset Value
0x0
0x0
0x0
0x0
0x00
0x00
Reset Value
0xFFFF
Publication No. SBC330-0HH/3