VV0670P001 View Datasheet(PDF) - Vision
Part Name
Description
MFG CO.
'VV0670P001' PDF : 36 Pages View PDF
Colour Processor Interface ASIC
2.2.5 Parallel Port Interface
The parallel port interface is designed to attach directly to the parallel printer port of a PC. As such it contains
8 bi-directional data lines, 4 control inputs and 5 status outputs for connection to the host parallel port. In
addition, a further 4 outputs, 5 inputs are provided to support pass-through parallel port designs. These two
ports are referred to as the Host Port and Pass-through Port.
Figure 2.5 : Parallel Port Interface Signals
Control
Host PC
Parallel
Port
Status
Data
H_STROBE
H_AUTOFD
H_INIT
H_SELECTIN
P_STROBE
P_AUTOFD
P_INIT
P_SELECTIN
CPiA Device
H_FAULT
H_ACK
H_BUSY
H_PERROR
H_SELECT
P_FAULT
P_ACK
P_BUSY
P_PERROR
P_SELECT
HP_DATA0:7
Control
Pass-
through
Port
Status
Data
This following sections give a guide to the low level protocols used to transfer command and image data over
the parallel port interface. They should be read in conjunction with the document "IEEE Std 1284 - Standard
Signaling method for a Bidirectional Parallel Peripheral Interface for Personal Computers". It is intended to
give users enough information to design and debug boards utilising the CPiA device.
2.2.5.6 Parallel Port Protocol
There are three classes of transfer that take place over the parallel port.
• IEEE Std 1284 Device ID Transfers
• Command / Status Transfers
• Image Stream Transfers
1284 Device ID transfers are used by the Microsoft Windows 95/98 operating systems to detect the presence
of the CPiA-based camera at boot time and load the approriate drivers.
Command and Status transfers are used to pass control information to the CPiA-based camera from the host
as well as returning state information back to the host.
Image Stream Transfers are used to transfer image data from CPiA to the host. This data can be in a
compressed or uncompressed format depending on how the CPiA has been set up via the associated host PC
software driver.
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02/07/98
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