FDC37C78-HT Standard Microsystems (SMSC), FDC37C78-HT Datasheet - Page 52

• Manufacturer Part Number: FDC37C78-HT
• Manufacturer: Standard Microsystems (SMSC)

Specifications of FDC37C78-HT

• Package Type: TQFP
• Lead Free Status / RoHS Status: Compliant

4) Issue Read/Write command.
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".
mode, the FDC clears the PCN value and the
status information to zero. Prior to issuing the
POWERDOWN
recommended that the user service all pending
interrupts through the Sense Interrupt Status
command.
Sense Interrupt Status
An interrupt signal on IRQ pin is generated by the
FDC for one of the following reasons:
1.Upon entering the Result Phase of:
2. End of Seek, Relative Seek, or Recalibrate
3. FDC requires a data transfer during the
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.
a. Read Data command
b. Read A Track command
c. Read ID command
d. Read Deleted Data command
e. Write Data command
f.
g. Write Deleted Data command
h. Verify command
command
execution phase in the non-DMA mode
SE
0
1
1
Format A Track command
Table 27 - Interrupt Identification
11
00
01
IC
Polling
Normal termination of Seek
or Recalibrate command
Abnormal termination of
Seek or Recalibrate
command
When exiting POWERDOWN
command,
INTERRUPT DUE TO
it
is
highly
52
The Seek, Relative Seek, and Recalibrate
commands have no result phase.
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
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.
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 28. The values are the same for MFM and
FM.
Drive
Status
Note that the spacing
obtains
drive
The Sense
status