CS5530 datasheet(63/241 Pages) NSC

63 / 241 page

Revision 4.1

www.national.com

Functional Description (Continued)

Table 3-19. Floppy Disk Idle Timer and Trap Related Registers

Bit

Description

F0 Index 81h

Power Management Enable Register 2 (R/W)

Reset Value = 00h

Floppy Disk Idle Timer Enable: Turn on Floppy Disk Idle Timer Count Register (F0 Index 9Ah) and generate an SMI

when the timer expires: 0 = Disable; 1 = Enable.

If an access occurs in the address ranges (listed below) the timer is reloaded with the programmed count.

Primary floppy disk: I/O Port 3F2h-3F5h, 3F7h,

Secondary floppy disk: I/O Port 372h-375h, 377h

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 85h/F5h[1].

F0 Index 82h

Power Management Enable Register 3 (R/W)

Reset Value = 00h

Floppy Disk Trap: 0 = Disable; 1 = Enable.

If this bit is enabled and an access occurs in the address ranges (listed below) an SMI is generated.

Primary floppy disk: I/O Port 3F2h-3F5h, 3F7h,

Secondary floppy disk: I/O Port 372h-375h, 377h

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 86h/F6h[1].

F0 Index 93h

Miscellaneous Device Control Register (R/W)

Reset Value = 00h

Floppy Drive Port Select: All system resources used to power manage the floppy drive use the primary or secondary

FDC addresses for decode: 0 = Secondary; 1 = Primary.

F0 Index 9Ah-9Bh

Floppy Disk Idle Timer Count Register (R/W)

Reset Value = 0000h

15:0

Floppy Disk Idle Timer Count: This idle timer is used to determine when the floppy disk drive is not in use so that it can

be powered down. The 16-bit value programmed here represents the period of floppy disk drive inactivity after which the

system is alerted via an SMI. The timer is automatically reloaded with the count value whenever an access occurs to the

configured floppy drive’s data port (I/O Port 3F5h or 375h). The counter uses a 1 second timebase.

To enable this timer set F0 Index 81h[1] = 1.

Top level SMI status is reported at F1BAR+Memory Offset 00h/02h[0].

Second level SMI status is reported at F0 Index 85h/F5h[1].

CS5530 Datasheet(PDF) 63 Page - National Semiconductor (TI)