net2890 ETC-unknow, net2890 Datasheet - Page 27

• Manufacturer Part Number: net2890
• Description: Interface Controller
• Manufacturer: ETC-unknow

Specification
4.5.5 Interrupt Endpoints
Interrupt endpoints are used for returning small amounts of status information to the host with a bounded
service period. The USB Specification Version 1.0 only defines interrupt endpoint data transfers from the
device to the host (IN endpoints). In the NET2890, both directions of interrupt data transfers are supported.
4.5.5.1 Interrupt Out Transactions
Interrupt Out endpoints are used to transfer data from a USB host to the NET2890 local bus. An interrupt
OUT transaction to an Interrupt OUT endpoint consists of the following:
The behavior of an Interrupt OUT endpoint is the same as a Bulk OUT endpoint, except for the toggle bit.
If the Interrupt Mode bit is cleared, the toggle bit of the Interrupt OUT endpoint is initialized to 0
(DATA0 PID), and behaves the same as a Bulk OUT endpoint. If the Interrupt Mode bit is set, the toggle
bit of the Interrupt OUT endpoint changes after each data packet is received from the host, without regard
to the Status stage.
Note: Interrupt write transactions are not supported in the Rev 1.0 USB Specification.
4.5.5.2 Interrupt In Endpoints
An Interrupt IN endpoint is polled at a rate which is specified in the endpoint descriptor. An interrupt
transaction from an Interrupt IN endpoint consists of the following:
The behavior of an Interrupt IN endpoint is the same as a Bulk IN endpoint, except for the toggle bit. If the
Interrupt Mode bit is cleared, the toggle bit of the Interrupt IN endpoint is initialized to 0 (DATA0 PID),
and behaves the same as a Bulk IN endpoint. An interrupt endpoint may be used to communicate rate
feedback information for certain types of isochronous functions. To support this mode, the Interrupt
Mode bit is set, and the toggle bit of the Interrupt IN endpoint changes after each data packet is sent to the
host, without regard to the Status stage.
____________________________________________________________________________________
Stage
OUT Token
Data (1/0)
Status
Stage
IN Token
Data (1/0)
Status
335 Pioneer Way, Mountain View, California 94041
TEL [phone] FAX [phone]
Packet Contents
OUT PID, address, endpoint, and CRC5
DATA PID, N data bytes, and CRC16
ACK, NAK, or STALL
Packet Contents
IN PID, address, endpoint, and CRC5
DATA PID, N data bytes, and CRC16
ACK
NetChip Technology, Inc., 1999
Rev 2.0, Draft 9, July 16, 1999
http://www.netchip.com
NET2890 USB Interface Controller
bytes
bytes
N+3
N+3
# of
# of
3
1
3
1
NET2890
NET2890
Source
Source
Host
Host
Host
Host
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