LPC47M192 View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
MFG CO.
'LPC47M192' PDF : 228 Pages View PDF
Data Transfer Termination
The FDC supports terminal count explicitly through the TC pin and implicitly through the underrun/overrun and end-
of-track (EOT) functions. For full sector transfers, the EOT parameter can define the last sector to be transferred in
a single or multi-sector transfer.
If the last sector to be transferred is a partial sector, the host can stop transferring the data in mid-sector, and the
FDC will continue to complete the sector as if a TC cycle was received. The only difference between these implicit
functions and TC cycle is that they return “abnormal termination” result status. Such status indications can be
ignored if they were expected.
Note that when the host is sending data to the FIFO of the FDC, the internal sector count will be complete when the
FDC reads the last byte from its side of the FIFO. There may be a delay in the removal of the transfer request signal
of up to the time taken for the FDC to read the last 16 bytes from the FIFO. The host must tolerate this delay.
Result Phase
The generation of the interrupt determines the beginning of the result phase. For each of the commands, a defined
set of result bytes has to be read from the FDC before the result phase is complete. These bytes of data must be
read out for another command to start.
RQM and DIO must both equal “1” before the result bytes may be read. After all the result bytes have been read, the
RQM and DIO bits switch to “1” and “0” respectively, and the CB bit is cleared, indicating that the FDC is ready to
accept the next command.
Command Set/Descriptions
Commands can be written whenever the FDC is in the command phase. Each command has a unique set of needed
parameters and status results. The FDC checks to see that the first byte is a valid command and, if valid, proceeds
with the command. If it is invalid, an interrupt is issued. The user sends a Sense Interrupt Status command which
returns an invalid command error. Refer to Table 16 for explanations of the various symbols used. Table 17 lists the
required parameters and the results associated with each command that the FDC is capable of performing.
Table 16 – Description of Command Symbols
SYMBOL
C
D
D0, D1
DIR
DS0, DS1
DTL
EC
EFIFO
EIS
EOT
SMSC DS – LPC47M192
NAME
Cylinder Address
Data Pattern
Drive Select 0-1
Direction Control
Disk Drive Select
Special Sector
Size
Enable Count
Enable FIFO
Enable Implied
Seek
End of Track
DESCRIPTION
The currently selected address; 0 to 255.
The pattern to be written in each sector data field during formatting.
Designates which drives are perpendicular drives on the
Perpendicular Mode Command. A “1” indicates a perpendicular
drive.
If this bit is 0, then the head will step out from the spindle during a
relative seek. If set to a 1, the head will step in toward the spindle.
DS1
DS0
DRIVE
0
0
Drive 0
0
1
Drive 1
By setting N to zero (00), DTL may be used to control the number of
bytes transferred in disk read/write commands. The sector size (N =
0) is set to 128. If the actual sector (on the diskette) is larger than
DTL, the remainder of the actual sector is read but is not passed to
the host during read commands; during write commands, the
remainder of the actual sector is written with all zero bytes. The CRC
check code is calculated with the actual sector. When N is not zero,
DTL has no meaning and should be set to FF HEX.
When this bit is “1” the “DTL” parameter of the Verify command
becomes SC (number of sectors per track).
This active low bit when a 0, enables the FIFO. A “1” disables the
FIFO (default).
When set, a seek operation will be performed before executing any
read or write command that requires the C parameter in the
command phase. A “0” disables the implied seek.
The final sector number of the current track.
Page 45
Rev. 03/30/05
DATASHEET
Share Link: 
