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This scanner calculates the numbers of X-direction pixels and Y-direction pixels of the image data to be
transferred to the initiator. The scanner performs this calculation by referencing the resolution and area up with the
SET WINDOW command. This data need not be issued if the number of pixels are known 1 the initiator.
The transfer format for this data is shown in the following illustration.
(MSB)
Number of X-direction pixels
(LSB)
(MSB)
Number of Y-direction pixels
(LSB)
(Reserved)
4.4.10 Scan command
The following table shows the normal sequence of the SCAN command when used with this scanner.
Step Bus phase Initiator operation
←←→→
Target operation
1 BUS FREE Verifies bus-free
2 ARBITRATION Obtains bus-usage right
3 SELECTION Selects target
→
Drives BSY signal
4 MESSAGE OUT Selects logical unit
→
5 COMMAND Specifies SCAN (CDB)
→
6 DATA OUT
→
Transfer data
7 STATUS
←
Reports GOOD status
8 MESSAGE IN
←
Reports message (Command Complete)
Releases BSY signal
9 BUS FREE
4.4.10.1 SCAN Command phase (initiator → target)
The Scan Command requests the target begin a scan operation. It is required for scanning color image, but
not required for scan B/W image.
Byte 0
3
4
7
8
F