LPC47M112 SMSC Corporation, LPC47M112 Datasheet - Page 32

• Manufacturer Part Number: LPC47M112
• Description: ENHANCED SUPER I/O CONTROLLER WITH LPC INTERFACE
• Manufacturer: SMSC Corporation

Enhanced Super I/O Controller with LPC Interface
Datasheet
BIT 0 and 1 DATA RATE SELECT
These bits control the data rate of the floppy controller. See Table 8 for the settings corresponding to the individual data
rates. The data rate select bits are unaffected by a software reset, and are set to 250 Kbps after a hardware reset.
BIT 2 through 4 PRECOMPENSATION SELECT
These three bits select the value of write precompensation that will be applied to the WDATA output signal. Table 7
shows the precompensation values for the combination of these bits settings. Track 0 is the default starting track
number to start precompensation. this starting track number can be changed by the configure command.
BIT 5 UNDEFINED
Should be written as a logic "0".
BIT 6 LOW POWER
A logic "1" written to this bit will put the floppy controller into manual low power mode. The floppy controller clock and
data separator circuits will be turned off. The controller will come out of manual low power mode after a software reset
or access to the Data Register or Main Status Register.
BIT 7 SOFTWARE RESET
This active high bit has the same function as the DOR RESET (DOR bit 2) except that this bit is self clearing.
Note: The DSR is Shadowed in the Floppy Data Rate Select Shadow Register, located at the offset 0x1F in the
runtime register block. Separator circuits will be turned off. The controller will come out of manual low power.
SMSC DS – LPC47M112
DRT1
DRIVE RATE
0
0
0
0
0
0
0
0
1
1
1
1
PRECOMP
432
111
001
010
011
100
101
110
000
DRT0
0
0
0
0
1
1
1
1
0
0
0
0
Table 7 - Precompensation Delays
SEL1
DATA RATE
1
0
0
1
1
0
0
1
1
0
0
1
Default: See Table 10
SEL0
DATASHEET
PRECOMPENSATION DELAY (nsec)
1
0
1
0
1
0
1
0
1
0
1
0
<2Mbps
Table 8 - Data Rates
125.00
166.67
208.33
250.00
Default
41.67
83.34
0.00
1Meg
1Meg
1Meg
2Meg
MFM
500
300
250
500
500
250
500
250
Page 32
DATA RATE
250
150
125
250
250
125
250
125
FM
---
---
---
---
DENSEL
2Mbps
Default
104.2
20.8
41.7
62.5
83.3
125
0
1
1
0
0
1
1
0
0
1
1
0
0
DRATE(1)
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
Rev. 02/02/2005