Power Management 8-6
8.05 WATCHDOG TIMER
The Watchdog Timer is extremely useful in embedded systems where human supervision
is not required.
Following a reset, the Watchdog is always disabled. If a hardware or software failure
occurs such that the Watchdog is not refreshed, a reset pulse is generated by the Watchdog
to restart the processor.
Jumper W20 must be installed to permit activation of the Watchdog. If jumper W20 is
removed, the Watchdog is disabled.
An user-defined program such as the one appearing below, must also be used in order to
enable and refresh the Watchdog.
INDEXREGISTER = 0x24;
DATAREGISTER = 0x26;
word Data;
outport( INDEXREGISTER , 0x111 );
Set bit 15 of Select Register to Low;
Data = inport( DATAREGISTER );
that sets the GPIO3 pin to Enabled.
Data = Data &(~0x8000);
Mask on bit 15.
outport( INDEXREGISTER , 0x111 );
outport( DATAREGISTER , Data );
outport( INDEXREGISTER , 0x007 );
Set bit 15 Gen. Purp. Ctrl Reg. to High;
Data = inport( DATAREGISTER );
that puts the GPIO3 pin in Output.
Data = Data | 0x8000;
Mask on bit 15.
outport( INDEXREGISTER , 0x007 );
outport( DATAREGISTER , Data );
Every 1.6 second (at least), toggle the bit 11 of the GPIO3 pin.
outport( INDEXREGISTER , 0x007 );
Toggle GPIO3 pin for the Watchdog;
Data = inport( DATAREGISTER );
that puts the GPIO3 pin High or Low.
Data = Data ^ 0x800;
Toggle bit 11 with XOR.
outport( INDEXREGISTER , 0x007 );
outport( DATAREGISTER , Data );
To disable the Watchdog, just put the bit 15 of the General Purpose Control
Register Low.
Summary of Contents for VIPer808
Page 21: ...Installing Memory 2 3 DIAGRAM 2 1 Assembly Top...
Page 22: ...Installing Memory 2 5 DIAGRAM 2 2 Assembly Bottom...
Page 26: ...Setting Jumpers 3 3 DIAGRAM 3 1 VIPer808 Jumper Locations with Default Settings...
Page 28: ...Setting Jumpers 3 6 TABLE 3 1a Jumper Settings W1 W4 W13 W14...
Page 29: ...Setting Jumpers 3 7 TABLE 3 1b AMD DX2 DX4 CPU Jumper Settings W1 W15 W15C...
Page 30: ...Setting Jumpers 3 8 TABLE 3 1c AMD 5x86 CPU Jumper Settings W1 W15 W15C...
Page 31: ...Setting Jumpers 3 9 TABLE 3 1d Intel CPU Jumper Settings W1 W15 W15C...
Page 32: ...Setting Jumpers 3 10 TABLE 3 1e SGS CPU Jumper Settings W1 W15 W15C...
Page 33: ...Setting Jumpers 3 11 TABLE 3 1f Jumper Settings W18 W20 W23...
Page 92: ...Memory I O Maps B 1 APPENDIX B MEMORY I O MAPS B 01 MEMORY MAPS DIAGRAM B 1 Memory Map Diagram...
Page 96: ...Mechanical Layout Block Diagram C 3 DIAGRAM C 1 Mechanical Specifications...
