Pixelink PL-A780 System Manual Download

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Developing Software for the PL-A780

Document No.: 04646-01

PixeLINK PL-A780

MACHINE VISION CAMERA

SYSTEM GUIDE

different types of pixel format supported, and provide controls to set all of these options. The
also provide information and control of isochronous streaming parameters (discussed later in
Section 6.6.2 on page 45).

For example to determine the current image width and height of the video data read the
register at offset

000Ch

(or address

FFFF F0D0 0A0Ch

using the example format 7 mode 0

control register offset). If this value is

0500 0400h

then the current width and height would be

1280 x 1024.

6.5.2 Camera Features

The camera features are used to control different functions of the camera, from things like
saturation and gamma to zoom and focus. A given camera will only support some of the
defined features so controlling software needs to determine which features are supported.
The IIDC specification defines the Inquiry Registers for feature presence. The values of these
registers will indicate which features are supported.

There are also separate inquiry registers for each feature defined in the IIDC specification.
The value of these registers will provide information about how the specific supported feature
can be controlled including: the minimum and maximum value of the feature, if the feature
can be controlled by the user (Manual_Inq), if the feature’s value can be adjusted
continuously by the camera (Auto_Inq), if the feature’s value can be adjusted once
automatically by the camera (One_Push_Inq), if the feature can be turned on and off
(On/Off_Inq) and if the feature can be controlled with its Absolute Value register (see Section
6.5.3 below).

A supported feature can be controlled through it’s control register. The registers allow
controlling software to set the value or change the mode of the feature.

6.5.3 Absolute Value CSRs

There can be a set of absolute value registers for each supported camera feature. The
absolute value registers allow for manual control of the feature using 32-bit IEEE floating
point values. This allows for exact values using engineering units instead of arbitrary values
(units for the absolute value registers are defined in Appendix B of the IIDC specification).
The IIDC specification defines the Absolute Value CSRs. Each set of absolute value CSRs
consist of three registers, a minimum value, a maximum value (both read only) and the
current value. The IIDC specification defines the offsets of the Absolute Value CSRs for each
of the camera features.

For example, to determine the location of the absolute value CSRs for the Brightness feature
read the register at offset

0700h

(or address

FFFF F0D0 0700h

). If the value of this register

was

0034 0380h

then the absolute value CSRs for Brightness would be located at offset

00D0 0E00h

(or address

FFFF F0D0 0E00h

), note that this offset is relative to the base

address

FFFF F000 0000h

not the IIDC base address. If the values at offsets

0E00h

0E04h

and

0E08h

were

0000 0000h

4000 0000h

, and

3F80 0000h

respectively then the min value

would be 0.0, the max would be 2.0 and the current value would be 1.0.

6.5.4 Advanced Feature CSRs

Some camera vendors may wish to implement features that are not defined by the IIDC
specification. This is done through the advanced feature register space. The IIDC
specification defines the Inquiry Register for Basic Functions which indicates if the camera
supports these vendor defined features. If they are supported then the offset for the