Canon CANOSCAN FB330 series Service Manual page 69

USB connector has A plug for connecting to upper layer and B plug for connecting to lower
layer.
3) USB data transfer
USB data is transferred in the following 4 data structures called "packet".
* Token packet
* Handshake packet
* Data packet
* Special packet
USB device may support multiple data transfer endpoints, so there are 4 types of data
transfer protocols.
* Isochronous transfer : Allocates a data transfer time to a device. Highest priority is given but
* Interrupt transfer
* Control transfer
* Bulk transfer
COPYRIGHT © 1999 CANON INC. CANOSCAN FB330/FB630 SERIES REV.0 OCT. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
A Plug
Figure 2-34
: Used to start a data transfer
: Used to report the status of a data transfer
: Used to send and receive data
: Used for other transfer
any error is not corrected.
: Periodically transfers data within a specified waiting time. Second
priority is given.
: Used to configure the host computer when USB device is attached/
removed.
: Lowest priority is given but larger amounts of data is sequentially
transferred to a free bus.
B Plug
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