at43312 ATMEL Corporation, at43312 Datasheet - Page 7

• Manufacturer Part Number: at43312
• Description: Self- And Bus- Powered Usb Hub Controller
• Manufacturer: ATMEL Corporation

Endpoint0
Endpoint0 is the AT43312’s default endpoint used for enu-
meration of the Hub and exchange of configuration infor-
mation and requests between the Host and the AT43312.
Endpoint0 supports control transfers.
The Hub Controller supports the following descriptors:
Device Descriptor, Configuration Descriptor, Interface
Descriptor, Endpoint Descriptor, and Hub Descriptor.
These Descriptors are described in detail on page 9
through page 16 of this document. Standard USB Device
Requests and class-specific Hub Requests are also sup-
ported through Endpoint0. There is no endpoint descriptor
for Endpoint0.
Status Change Register
An IN Token packet from the Host to Endpoint1 indicates a
request for port change status. If the Hub has not detected
any change on its ports, nor any changes in itself, then all
bits in this register will be 0 and the Hub Controller will
return a NAK to requests on Endpoint1. If any of bits 0-4 is
1, the Hub Controller will transfer the whole byte. The Hub
5-7
Bit
0
1
2
3
4
Function
Hub status change
Port1 status change
Port2 status change
Port3 status change
Port4 status change
Reserved
Value
000
0
1
0
1
0
1
0
1
0
1
Meaning
No change in status
Change in status detected
No change in status
Change in status detected
No change in status
Change in status detected
No change in status
Change in status detected
No change in status
Change in status detected
Default values
Endpoint1
Endpoint1, an interrupt endpoint, is used by the Hub Con-
troller to send status change information to the Host.
The Hub Controller samples the changes at the end of
every frame at time marker EOF2 in preparation for a
potential data transfer in the subsequent frame. The sam-
pled information is stored in a byte-wide register, the Status
Change Register , using a bitmap scheme.
Each bit in the Status Change Register corresponds to one
port as shown below:
Controller will continue to report a status change when
polled until that particular change has been removed by a
Clear_Port_Feature request from the Host. No status
change will be reported by Endpoint1 until the AT43312
has been enumerated and configured by the Host via
Endpoint0.
7