CY7C656xx
Document Number: 38-08037 Rev. *M
Page 12 of 25
Configuration Options
Systems using CY7C656xx have the option of using a fuse
ROM, which is preset at the factory to configure the hub.
Otherwise, it must have an external EEPROM for the device to
have a unique VID, PID, and DID. The CY7C656xx can commu-
nicate with SPI EEPROM that are either double byte addressed
or single byte with the ninth bit within the instruction byte, such
as the 24LC040 parts use. The 25LC080 EEPROM uses the
double byte address format. Therefore, the CY7C656xx can
communicate with these parts. The '010s and '020s use the
same command format that is used to interface with the ‘040 and
hence these can also be used to interface with the CY7C656xx.
If the attached EEPROM is blank (0xFF) the hub enumerates as
a vendor class device. In this configuration, the hub connects to
the Cypress driver to allow programming of the EEPROM. When
the EEPROM is programmed, a power cycle configures the chip
as a hub class device.
0xD0 Load
With this EEPROM format, only a unique VID, PID, and DID must
be present in the external SPI EEPROM. The contents of the
EEPROM must contain this information in the following format:
0xD2 Load
Byte 0: 0xD2
Needs to be programmed with 0xD2
Byte 1: VID (LSB)
Least Significant Byte of Vendor ID
Byte 2: VID (MSB)
Most Significant Byte of Vendor ID
Byte 3: PID (LSB)
Least Significant Byte of Product ID
Byte 4: PID (MSB)]
Most Significant Byte of Product ID
Byte 5: Reserved
Reserved
Byte 6: DID (MSB)]
Most Significant Byte of Device ID
Byte 7: EnabledOvercurrentTimer[3:0],
DisabledOvercurrentTimer[3:0]
Count time in ms for filtering overcurrent detection. Bits 7–4
are for an enabled port, and bits 3–0 are for a disabled port.
Both range from 0 ms to 15 ms. See section Port Indicators
on page 5. Default: 8 ms = 0x88.
Byte 8: ActivePorts[3:0], RemovablePorts[3:0]
Bits 7–4 are the ActivePorts[3:0] bits that indicates if the cor-
responding port is usable. For example, a two-port hub that
uses ports 1 and 4 would set this field to 0x09. The total num-
ber of ports reported in the Hub Descriptor: bNbrPorts field is
calculated from this. Bits 3–0 are the RemovablePorts[3:0]
bits that indicates whether the corresponding logical port is
removable (set to high). Logical port numbers are from 1 to n
where n is the total number of active ports. If port 2 is disabled
then physical ports 1, 3, and 4 map to logical ports 1, 2, and
3. These bit values are reported appropriately in the
HubDescriptor:DeviceRemovable field. Default: 0xFF.
Byte 9: MaximumPower
This value is reported in the ConfigurationDescriptor:bMax-
Power field and is the current in 2 mA increments that is re-
quired from the upstream hub. Default: 0x28 = 80 mA for full
speed and 0x57 = 174 mA for high speed.
Byte 10: HubControllerPower
This value is reported in the HubDescriptor:bHubContrCur-
rent field and is the current in milliamperes required by the
hub controller. Default: 0x50 = 80 mA for full speed and 0xAE
= 174 mA for high speed.
Byte 11: PowerOnTimer
This
value
is
reported
in
the
HubDescriptor:
bPwrOn2PwrGood field and is the time in 2 ms intervals from
the SetPortPower command until the power on the corre-
sponding downstream port is good. Default: 0x32 = 100 ms.
Byte
Value
0
0xD0
1
VID (LSB)
2
VID (MSB)
3
PID (LSB)
4
PID (MSB)
5
reserved
6
DID (MSB)
Byte
Value (MSB->LSB)
0
0xD2
1VID (LSB)
2
VID (MSB)
3PID (LSB)
4
PID (MSB)
5
reserved
6
DID (MSB)
7
EnabledOverCurrentTimer[3:0],
DisableOvercurrentTimer[3:0]
8
ActivePorts[3:0], RemovablePorts[3:0]
9MaxPower
10
HubControllerPower
11
PowerOnTimer
12
IllegalHubDescriptor, CompoundDevice,
FullspeedOnly, NoPortIndicators, Reserved,
GangPowered, Reserved, Reserved
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