CY7C68310
Document 38-08030 Rev. *H
Page 8 of 34
USB Mass Storage Class Bulk-Only Transport Specification.
The ATACB must be 16 bytes in length. The following table and
text defines the fields of the ATACB.
Table 5-1. ATACB Field Descriptions
Byte
Field Name
Field Description
0
bVSCBSignature
This field indicates to the CY7C68310 that the ATACB contains a vendor-
specific command block. This value of this filed must match the value in
EEPROM address 0x06h for this vendor-specific command to be recognized.
1
bVSCBSubCommand
This field must be set to 0x024h for ATACB commands.
2
bmATACBActionSelect
This field controls the execution of the ATACB according to the bitfield values:
Bit 7 IdentifyPacketDevice - This bit indicates that the data phase of the
command will contain ATAPI (0xA1h) or ATA (0xECh) IDENTIFY device data.
Setting IdentifyPacketDevice when the data phase does not contain IDENTIFY
device data will result in unspecified device behavior.
0 = Data phase does not contain IDENTIFY device data
1= Data phase contains ATAPI or ATA IDENTIFY device data
Bit 6 UDMACommand - This bit enables supported UDMA device transfers.
Setting this bit when a non-UDMA capable device is attached will result in
undetermined behavior.
0 = Do not use UDMA device transfers (only use PIO mode)
1= Use UDMA device transfers
Bit 5 DEVOverride - This bit determines whether the DEV bit value is taken
from the CY7C68310 configuration data or from the ATACB.
0 = The DEV bit will be taken from EEPROM address 0x05h, bit 5
1= The DEV bit will be taken from the ATACB field 0x0B, bit 4
Bit 4:3 DPErrorOverride - These bits control the Device and Phase Error
override feature. These bits shall not be set in conjunction with bmATACBTask-
FileRead.
00 = Data accesses are halted if a device or phase error is detected
01 = Data accesses are halted if a device error is detected, but not a phase error
10 = Data accesses are halted if a phase error is detected, but not a device error
11 = Neither device or phase errors will result in halting of data accesses
Bit 2 PollAltStatOverride - This bit determines whether or not the Alternate
Status register will be polled and the BSY bit will be used to qualify the start of
ATACB operation.
0 = The AltStat register will be polled until BSY=0 before proceeding with the
ATACB operation
1= The ATACB operation will be executed without polling the AltStat register
Bit 1 DeviceSelectionOverride - This bit determines when the device selection
will be performed in relation to the command register write accesses.
0 = Device selection will be performed prior to command register write
accesses
1 = Device selection will be performed following command register write
accesses
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