Specification
NET2272 USB Peripheral Controller
______________________________________________________________________________
NetChip Technology, Inc., 2003
Patent Pending
335 Pioneer Way, Mountain View, California 94041
TEL (650) 526-1490
FAX (650) 526-1494
http://www.netchip.com
Rev 1.2, October 15, 2003
42
5.6.5 Interrupt Endpoints
Interrupt endpoints are used for sending or receiving small amounts of data to the host with a bounded service
period.
5.6.5.1 Interrupt Out Transactions
Interrupt Out endpoints are used to transfer data from a USB host to the NET2272 local bus. An interrupt OUT
transaction to an Interrupt OUT endpoint consists of the following:
Stage
Packet Contents
Number of bytes
Source
OUT Token
OUT PID, address, endpoint, and CRC5
3
Host
Data (1/0)
DATA PID, N data bytes, and CRC16
N+3
Host
Status
ACK, NAK, or STALL
1
NET2272
The behavior of an Interrupt OUT endpoint is almost 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 that the
PING protocol is not allowed for Interrupt OUT endpoints, as per the USB Specification.
5.6.5.2 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:
Stage
Packet Contents
Number of bytes
Source
IN Token
IN PID, address, endpoint, and CRC5
3
Host
Data (1/0)
DATA PID, N data bytes, and CRC16
N+3
NET2272
Status
ACK
1
Host
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.
5.6.5.3 High Bandwidth INTERRUPT Endpoints
From the USB device point of view, high-bandwidth INTERRUPT endpoints are the same as BULK endpoints,
except that the MAXPKT can be any value from 1 to 1024. Normal INTERRUPT endpoints in full-speed mode can
set MAXPKT from 1 to 64.
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
