Control System; Outline; Usb Interface - Canon CANOSCAN D660U Service Manual

IV. CONTROL SYSTEM
A. Outline
CanoScan D660U is not equipped with the CPU and the scanner is controlled by the device
driver installed in the host computer. The device driver includes the scanner control program,
which sets a command directly to the ASIC to control the scanner.
B. USB Interface
The scanner is connected to the host computer via USB interface. USB (Universal Serial
Bus) is the next generation general-purpose input-output interface to connect the computer
peripheral devices.
1. Features of USB includes;
* Connects peripheral devices by a tree structure.
* Connects up to 127 devices by a tree structure.
* Connects by 12 Mbps of "full speed mode" or 1.5 Mbps of "low speed mode". The scanner is
conforming to "full speed mode".
* Supports hot plug (able to connect/disconnect with the power ON)
2. Connection to USB devices
USB devices are connected to a host computer by a tree structure consisting of device called
"node" and "hub" which is a group of "node" as shown in Figure 2-20. The tree structure has
the following conditions.
* Able to connect up to 127 "node" and "hub" in total.
* Limited up to 6 layers.
* USB cable must be 5 meters or shorter.
COPYRIGHT © 2000 CANON INC.
Host computer
Hub 1
Hub 2 Node
Hub 3 Hub 6
Hub 4 Node
Hub 5 Node
Node
Figure 2-20
CANOSCAN D660U REV.0 JULY 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
Node
Node
Node
Node
Node
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