41
Western Digital Hard Disk Drive OEM Specification
9
General Operation Descriptions
9.1
Reset Response
There are three types of reset in ATA as follows:
Power On Reset (POR)
The device executes a series of electrical circuitry diagnostics.
COMRESET
COMRESET is issued in Serial ATA bus.
The device resets the interface circuitry as well as Soft Reset.
Soft Reset (Software Reset
) SRST bit in the Device Control Register is set, and then is reset.
The device resets the interface circuitry according to the Set Features requirement.
The actions of each reset are shown in Table 32.
POR
COMRESET Soft Reset
Aborting Host interface
-
o
o
Aborting Device operation
-
(*1)
(*1)
Initialization of hardware
o
x
x
Internal diagnostic
o
x
x
Spinning spindle
(*6)
x
x
Initialization of registers (*2)
o
o
o
Reverting programmed parameters to default
o
(*3)
(*3)
- Number of CHS
(set by Initialize Device Parameter)
- Multiple mode
- Write cache
- Read look-ahead
- ECC bytes
Disable Standby timer
o
x
x
Power mode
(*5)
(*4)
(*4)
o ---- Execute
x ---- Not execute
Table 32 Reset Response
Table Notes
(*1)
Execute after the data in write cache has been written.
(*2)
Default value on POR is shown in Table 34 Default Register Values on page 42.
(*3)
The Set Features command with Feature register = CCh enables the device to revert these parameters to
the power on defaults.
(*4)
In the case of Sleep mode, the device goes to Standby mode. In other case, the device does not change
current mode.
(*5)
Idle when Power-Up in Standby feature set is disabled. Standby when Power-Up in Standby feature set is
enabled.
(*6)
Spinning up when Power-Up in Standby feature set is disabled. Standby when Power-Up in Standby feature
set is enabled.
