LPC47M182 SMSC Corporation, LPC47M182 Datasheet - Page 53

• Manufacturer Part Number: LPC47M182
• Description: ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC
• Manufacturer: SMSC Corporation

Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
6.5
6.5.1
SMSC LPC47M182
BIT NO.
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.
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].
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.
1,0
7
6
5
4
3
2
WP
T0
HD
DS1,0
SYMBOL
Write
Protected
Track 0
Head Address Indicates the status of the HDSEL pin.
Drive Select
Table 6.15 - Status Register 3
NAME
DATASHEET
Unused. This bit is always "0".
Indicates the status of the WRTPRT pin.
Unused. This bit is always "1".
Indicates the status of the TRK0 pin.
Unused. This bit is always "1".
Indicates the status of the DS1, DS0 pins.
53
Revision 1.8 SMSC/Non-SMSC Register Sets (02-24-05)
DESCRIPTION