LPC47M172 Datasheet, PDF (70/227 Pages) SMSC Corporation – ADVANCED I/O CONTROLLER WITH MOTHERBOARD GLUE LOGIC

Advanced I/O Controller with Motherboard GLUE Logic
Datasheet
Note that if implied seek is not enabled, the read and write commands should be preceded by:
1. Seek command - Step to the proper track
2. Sense Interrupt Status command - Terminate the Seek command
3. Read ID - Verify head is on proper track
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 is 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.
6.19 Sense Interrupt Status
An interrupt signal is generated by the FDC for one of the following reasons:
1. Upon entering the Result Phase of:
a. Read Data command
b. Read A Track command
c. Read ID command
d. Read Deleted Data command
e. Write Data command
f. Format A Track command
g. Write Deleted Data command
h. Verify command
2. End of Seek, Relative Seek, or Recalibrate command
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.
Table 6.25 - Interrupt Identification
SE IC
INTERRUPT DUE TO
0
11 Polling
1
00 Normal termination of Seek
or Recalibrate command
Abnormal termination of
1
01 ^{Seek or Recalibrate}
command
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.
SMSC/Non-SMSC Register Sets (Rev. 02-27-04)
Page 70
DATASHEET
SMSC LPC47M172