Rockwell Brooktree Bt848EVK, Техническое справочное руководство

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Bt848 Software Specification
I
2
C and GPIO Function Support
8 UG848_3A
Bt848
Software Specification
Brooktree
®
I
2
C and GPIO Function Support
The Bt848 device driver conforms to the Video for Windows specification, which does not provide
an interface for proprietary ports such as the I
2
C and the General Purpose I/O (GPIO) port. There-
fore, applications attempting to access these proprietary ports must bypass the VfW interface. This
is illustrated in Figure 4.
The I
2
C and GPIO ports are accessed by an application through memory pointers. The two
memory pointers to the I
2
C and GPIO ports are located in the Bt848 memory mapped register
space. The Bt848 capture driver provides specific messages that an application uses to retrieve the
I
2
C and GPIO memory pointers. After the Bt848 capture driver has been opened, the application
uses the VfW messaging system to send the specific messages. The Bt848 capture then recognizes
the messages, and retrieves the memory pointers.
Modifiable Dialog Boxes
The Dialog Dynamic Link Library (DLL) contains dialogs and other resources required for using
the Bt848 software package. These resources include dialogs for basic video controls (brightness,
contrast, hue, saturation), video source selection, video standard (NTSC, PAL, SECAM), image
size, capture format, etc. The dialogs may be used as provided or may be modified by the user as
suited for each application. The source code is provided for the Dialog Dynamic Link Library. See
the Bt848 Users Guide for a description of the dialog boxes as they are provided in the Dynamic
Link Library.
Figure 4. Bypassing VfW to Access the I
2
C and GPIO Ports
Application
Microsoft
Video for Windows
Bt848 Driver
I
2
C
GPIO