Fujitsu MHU2100AT, Product Manual

Page: 88 / 278

Interface
5-12 C141-E202-01EN
- Bit 7: Busy (BSY) bit. This bit is set whenever the Command register is
accessed. Then this bit is cleared when the command is completed.
However, even if a command is being executed, this bit is 0 while data
transfer is being requested (DRQ bit = 1).When BSY bit is 1, the host
system should not write the command block registers. If the host
system reads any command block register when BSY bit is 1, the
contents of the Status register are posted. This bit is set by the device
under following conditions:
(a) Within 400 ns after RESET- is negated or SRST is set in the
Device Control register, the BSY bit is set. the BSY bit is cleared,
when the reset process is completed.
The BSY bit is set for no longer than 15 seconds after the IDD
accepts reset.
(b) Within 400 ns from the host system starts writing to the
Command register.
(c) Within 5
µ
s following transfer of 512 bytes data during execution
of the READ SECTOR(S), WRITE SECTOR(S), or WRITE
BUFFER command.
Within 5
µ
s following transfer of 512 bytes of data and the
appropriate number of ECC bytes during execution of READ
LONG or WRITE LONG command.
- Bit 6: Device Ready (DRDY) bit. This bit indicates that the device is
capable to respond to a command.
The IDD checks its status when it receives a command. If an error is
detected (not ready state), the IDD clears this bit to 0. This is cleared
to 0 at power-on and it is cleared until the rotational speed of the
spindle motor reaches the steady speed.
- Bit 5: The Device Write Fault (DF) bit. This bit indicates that a device fault
(write fault) condition has been detected.
If a write fault is detected during command execution, this bit is
latched and retained until the device accepts the next command or
reset.
- Bit 4: Device Seek Complete (DSC) bit. This bit indicates that the device
heads are positioned over a track.
In the IDD, this bit is always set to 1 after the spin-up control is
completed.
- Bit 3: Data Request (DRQ) bit. This bit indicates that the device is ready to
transfer data of word unit or byte unit between the host system and the
device.
- Bit 2: Always 0.
- Bit 1: Always 0.
- Bit 0: Error (ERR) bit. This bit indicates that an error was detected while the
previous command was being executed. The Error register indicates
the additional information of the cause for the error.