Power Management 8-4
8.04 POWER FAIL DETECTION CIRCUIT
The Power Failure Detector always monitors:
•
The backup battery to warn of a low battery condition, and
•
The +5V power supply to detect when it falls below 4.75V.
If either of the two above conditions occur, the PFO (Power Fail Output signal) goes low.
In the case of the +5V power supply, a reset will result as explained in the previous
section (8.03.2). In the case of the low battery, what happens will depend on the setting of
the W21 jumper and user-defined algorithm.
The W21 jumper, when shorted, will generate a NMI (Non Maskable Interrupt), through
the IOCHK* line, when the PFO goes low. In turn, this NMI may be serviced by an
interrupt handler to locate the source and notify the user or the system.
If the W21 jumper is left open, no NMI is generated, however an algorithm could be used
to detect a low battery condition and respond accordingly. An example of such an user-
defined program appears below.
INDEXREGISTER = 0x24;
DATAREGISTER = 0x26;
boolean Good;
word Data;
outport( INDEXREGISTER , 0x111 );
Set bit 13 Pin Select Register to Low;
Data = inport( DATAREGISTER );
that sets the GPIO1 pin to Enabled.
Data = Data &(~0x2000);
Mask on bit 13.
outport( INDEXREGISTER , 0x111 );
outport( DATAREGISTER , Data );
outport( INDEXREGISTER , 0x007 );
Set bit 15 Gen. Purp.Ctrl Reg. to High;
Data = inport( DATAREGISTER );
that puts the GPIO1 pin in Input.
Data = Data &(~0x2000);
Mask on bit 15.
outport( INDEXREGISTER , 0x007 );
outport( DATAREGISTER , Data );
Read the PF0 signal …
outport( INDEXREGISTER , 0x007 );
Read the GPIO1 signal (Pwr Fail 0utput).
Data = inport( DATAREGISTER );
If Good is True then the battery is OK,
If (Data & 0x200) Good = True;
else the battery voltage is Low.
else Good = False;
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...
