LPC47M182 datasheet(53/223 Pages) SMSC

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Advanced I/O Controller with Motherboard GLUE Logic

Datasheet

SMSC LPC47M182

Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)

DATASHEET

Table 6.15 - Status Register 3

BIT NO.

SYMBOL

NAME

DESCRIPTION

Unused. This bit is always "0".

Write

Protected

Indicates the status of the WRTPRT pin.

Unused. This bit is always "1".

Track 0

Indicates the status of the TRK0 pin.

Unused. This bit is always "1".

Head Address Indicates the status of the HDSEL pin.

1,0

DS1,0

Drive Select

Indicates the status of the DS1, DS0 pins.

RESET

There are three sources of system reset on the FDC: the nPCI_RESET pin, a reset generated via a bit in

the DOR, and a reset generated via a bit in the DSR. At power on, a Power On Reset initializes the FDC.

All resets take the FDC out of the power down state.

All operations are terminated upon a nPCI_RESET, and the FDC enters an idle state. A reset while a disk

write is in progress will corrupt the data and CRC.

On exiting the reset state, various internal registers are cleared, including the Configure command

information, and the FDC waits for a new command. Drive polling will start unless disabled by a new

Configure command.

nPCI_RESET Pin (Hardware Reset)

The nPCI_RESET pin is a global reset and clears all registers except those programmed by the Specify

command. The DOR reset bit is enabled and must be cleared by the host to exit the reset state.

DOR Reset vs. DSR Reset (Software Reset)

These two resets are functionally the same. Both will reset the FDC core, which affects drive status

information and the FIFO circuits. The DSR reset clears itself automatically while the DOR reset requires

the host to manually clear it. DOR reset has precedence over the DSR reset. The DOR reset is set

automatically upon a pin reset. The user must manually clear this reset bit in the DOR to exit the reset

state.

6.5

MODES OF OPERATION

The FDC has three modes of operation, PC/AT mode, PS/2 mode and Model 30 mode. These are

determined by the state of the Interface Mode bits in FDC logical device -CRF0[3,2].

6.5.1

PC/AT mode

The PC/AT register set is enabled, the DMA enable bit of the DOR becomes valid (controls the interrupt

and DMA functions), and DENSEL is an active high signal.

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