USB2512A Standard Microsystems Corp., USB2512A Datasheet - Page 26

• Manufacturer Part Number: USB2512A
• Description: Usb2512a Usb 2.0 High-speed 2-port Hub Controller
• Manufacturer: Standard Microsystems Corp.

Revision 1.96 (07-11-08)
4.3.2
4.3.3
4.3.4
Byte Count = N
Byte Count = N
S
1
S
1
Slave Address
8
8
Slave Address
Block Read
A Block Read differs from a block write in that the repeated start condition exists to satisfy the I
specification’s requirement for a change in the transfer direction.
Invalid Protocol Response Behavior
Registers that are accessed with an invalid protocol are not updated. A register is only updated
following a valid protocol. The only valid protocols are Write Block and Read Block, which are
described above.
The Hub only responds to the hardware selected Slave Address.
Attempting to communicate with the Hub over SMBus with an invalid slave address or invalid protocol
results in no response, and the SMBus Slave Interface returns to the idle state.
The only valid registers that are accessible by the SMBus slave address are the registers defined in
the Registers Section. See
General Call Address Response
The Hub does not respond to a general call address of 0000_000b.
Slave Device Time-Out
According to the SMBus Specification, V1.0 devices in a transfer can abort the transfer in progress
and release the bus when any single clock low interval exceeds 25ms (T
have detected this condition must reset their communication and be able to receive a new START
condition no later than 35ms (T
Note: Some simple devices do not contain a clock low drive circuit; this simple kind of device typically
7
7
resets its communications port after a start or stop condition. The Slave Device Time-Out must
be implemented.
A
1
A
1
Data byte 1
Wr
Data byte 1
1
8
8
Wr
1
A
1
Section 4.3.3
Register Address
A
1
TIMEOUT, MAX
Figure 4.1 Block Write
Figure 4.2 Block Read
A
1
A
1
DATASHEET
Block Write
Register Address
8
Block Read
Data byte 2
Data byte 2
for the response to undefined registers.
26
8
).
8
8
1
A
A
1
A
1
S
1
A
1
Slave Address
USB 2.0 Hi-Speed 2-Port Hub Controller
...
Data byte N
Data byte N
7
TIMEOUT, MIN
8
8
Rd
1
SMSC USB2512A
). Devices that
1
A
A
1
A
1
Datasheet
P
1
1
P
...
2
C