LPC47B37X View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
MFG CO.
LPC47B37X
SMSC -> Microchip
'LPC47B37X' PDF : 254 Pages View PDF
The Seek, Relative Seek, and Recalibrate commands have no result phase. The Sense Interrupt Status
command must be issued immediately after these commands to terminate them and to provide verification
of the head position (PCN). The H (Head Address) bit in ST0 will always return a "0". If a Sense Interrupt
Status is not issued, the drive will continue to be BUSY and may affect the operation of the next command.
Sense Drive Status
Sense Drive Status obtains drive status information. It has not execution phase and goes directly to the
result phase from the command phase. Status Register 3 contains the drive status information.
Specify
The Specify command sets the initial values for each of the three internal times. The HUT (Head
Unload Time) defines the time from the end of the execution phase of one of the read/write commands
to the head unload state. The SRT (Step Rate Time) defines the time interval between adjacent step
pulses. Note that the spacing between the first and second step pulses may be shorter than the
remaining step pulses. The HLT (Head Load Time) defines the time between when the Head Load
signal goes high and the read/write operation starts. The values change with the data rate speed
selection and are documented in Table 26. The values are the same for MFM and FM.
The choice of DMA or non-DMA operations is made by the ND bit. When this bit is "1", the non-DMA
mode is selected, and when ND is "0", the DMA mode is selected. In DMA mode, data transfers are
signaled by the DMA request cycles. Non-DMA mode uses the RQM bit and the interrupt to signal data
transfers.
Configure
The Configure command is issued to select the special features of the FDC. A Configure command
need not be issued if the default values of the FDC meet the system requirements.
Table 26 - Drive Control Delays (ms)
HUT
SRT
2M 1M 500K 300K 250K 2M 1M 500K 300K 250K
0 64 128 256 426 512 4
8
16 26.7 32
14
8
16 26.7 32 3.75 7.5 15 25 30
.. ..
..
..
..
..
..
..
..
..
..
E 56 112 224 373 448 0.5
1
2 3.33 4
F 60 120 240 400 480 0.25 0.5
1 1.67 2
2M
00
64
01
0.5
02
1
..
..
7F
63
7F
63.5
HLT
1M
500K
300K
250K
128
256
426
512
1
2
3.3
4
2
4
6.7
8
..
..
..
.
126
252
420
504
127
254
423
508
65
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