FDC37N769_07 SMSC [SMSC Corporation], FDC37N769_07 Datasheet - Page 52

• Manufacturer Part Number: FDC37N769_07
• Description: 3.3V Super I/O Controller with Infrared Support for Portable Applications
• Manufacturer: SMSC [SMSC Corporation]

Recalibrate
This command causes the read/write head within the FDC to retract to the track 0 position. The FDC clears the
contents of the PCN counter and checks the status of the nTR0 pin from the FDD. As long as the nTR0 pin is low,
the DIR pin remains 0 and step pulses are issued. When the nTR0 pin goes high, the SE bit in Status Register 0 is
set to “1” and the command is terminated. If the nTR0 pin is still low after 79 step pulses have been issued, the
FDC sets the SE and the EC bits of Status Register 0 to “1” and terminates the command. Disks capable of handling
more than 80 tracks per side may require more than one Recalibrate command to return the head back to physical
Track 0.
The Recalibrate command does not have a result phase. The Sense Interrupt Status command must be issued after
the Recalibrate command to effectively terminate it and to provide verification of the head position (PCN). During the
command phase of the recalibrate operation, the FDC is in the BUSY state, but during the execution phase it is in a
NON-BUSY state. At this time, another Recalibrate command may be issued, and in this manner parallel Recalibrate
operations may be done on up to four drives at once.
Upon power up, the software must issue a Recalibrate command to properly initialize all drives and the controller.
Seek
The read/write head within the drive is moved from track to track under the control of the Seek command. The FDC
compares the PCN, which is the current head position, with the NCN and performs the following operation if there is a
difference:
The rate at which step pulses are issued is controlled by SRT (Stepping Rate Time) in the Specify command. After
each step pulse is issued, NCN is compared against PCN, and when NCN = PCN the SE bit in Status Register 0 is
set to “1” and the command is terminated.
During the command phase of the seek or recalibrate operation, the FDC is in the BUSY state, but during the
execution phase it is in the NON-BUSY state. At this time, another Seek or Recalibrate command may be issued,
and in this manner, parallel seek operations may be done on up to four drives at once.
Note that if implied seek is not enabled, the read and write commands should be preceded by:
1)
2)
3)
4)
The Seek command does not have a result phase. Therefore, it is highly recommended that the Sense Interrupt
Status command be issued after the Seek command to terminate it and to provide verification of the head position
(PCN). The H bit (Head Address) in ST0 will always return to a “0”. When exiting POWERDOWN mode, the FDC
clears the PCN value and the status information to zero. Prior to issuing the POWERDOWN command, it is highly
recommended that the user service all pending interrupts through the Sense Interrupt Status command.
Sense Interrupt Status
An interrupt signal on FINT pin is generated by the FDC for one of the following reasons:
1.
2.
3.
The Sense Interrupt Status command resets the interrupt signal and, via the IC code and SE bit of Status Register 0,
identifies the cause of the interrupt
SMSC DS – FDC37N769
PCN < NCN: Direction signal to drive set to
PCN > NCN: Direction signal to drive set to
Seek command - Step to the proper track
Sense Interrupt Status command - Terminate the Seek command
Read ID - Verify head is on proper track
Issue Read/Write command.
Upon entering the Result Phase of:
a.
b.
c.
d.
e.
f.
g.
h.
End of Seek, Relative Seek, or Recalibrate command
FDC requires a data transfer during the execution phase in the non-DMA mode
Read Data command
Read A Track command
Read ID command
Read Deleted Data command
Write Data command
Format A Track command
Write Deleted Data command
Verify command
DATASHEET
“1” (step in) and issues step pulses.
“0” (step out) and issues step pulses.
Page 52 of 137
Rev. 02-16-07