Firewire IIDC (DCAM) Windows driver

Table of Contents

• Introduction
• Video formats, modes, and frame rates
• Firewire specific parameters
• Configuration
• MEDM screens

Introduction

This is a driver for Firewire (IEEE 1394) cameras that follow the IIDC/DCAM specification. This industry standard allows a single driver to control cameras from any manufacturer, using any of the supported video formats and features.

This driver runs only on Windows. It uses the Carnegie Mellon 1394 camera driver and library. There is also an areaDetector Firewire driver for Linux available from the Diamond Light Source.

This driver inherits from ADDriver. It implements many of the parameters in NDStdDriverParam_t (see asynNDArryDriver.h) and in ADStdDriverParam_t (see ADArrayDriver.h). It also implements a number of parameters that are specific to the Firewire cameras. The firewireWinDCAM class documentation describes this class in detail.

The IIDC/DCAM specification defines standard ways that manufacturers must implement features like shutter time, white balance, frame sizes, frame rates, etc. There is a standard way to determine whether or not a particular camera supports a particular feature. If it does then there is a standard way of querying the allowed range of values for that feature. This makes it quite easy to write a driver that can support cameras with any capabilities from any manufacturer.

Video formats, modes, and frame rates

The DCAM specification defines standard video frame sizes, color modes and frames rates. The following tables lists these standard formats and mode. Video format 7 is special. It allows defining an ROI on the camera to read out. The pixel resolution with which the size and position of this ROI can be defined can be queried, and is not necessarily a single pixel. In Format 7 the frame rate settings do not apply, and the frame rate is determined by the size of the Fireware data packets.

The following tables lists the standard frame rates for formats 0, 1 and 2. Note that not all frame rates are supported by the IIDC standard for every format and mode, and even when a frame rate is supported by the standard it may not be implemented for a particular camera. In Format 7 the frame rate settings do not apply, and the frame rate is determined by the size of the Fireware data packets. The areaDetector driver currently sets the Format 7 packet size to the vendor recommended size, which typically results in the maximum possible frame rate.

The DCAM specification defines 22 standard features, which control things such as the brightness, white balance, shutter time, etc.. For each feature the standard defines control in both device units (12-bit integers) and absolute units (floating point). For example shutter time may support absolute seconds, as well as device units. A feature may or may not be supported on a particular camera. If it is supported it may or may not permit control in absolute units. Each feature may support both manual control and automatic control (e.g. automatic gain control). The following tables lists these standard features.

Firewire specific parameters

The firewireWinDCAM driver implements the following parameters in addition to those in asynNDArrayDriver.h and ADDriver.hh. Note that to reduce the width of this table the enum names have been split into 2 lines, but these are just a single name, for example mar345ScanSize.

Configuration

The firewireWinDCAM driver is created with the WinFDC_Config command, either from C/C++ or from the EPICS IOC shell.

WinFDC_Config(const char *portName, const char* camid, 
              int maxBuffers, size_t maxMemory, 
              int priority, int stackSize)
  

For details on the meaning of the parameters to this function refer to the detailed documentation on the WinFDC_Config function in the firewireWinDCAM.cpp documentation and in the documentation for the constructor for the FirewireWinDCAM class.

There an example IOC boot directory and startup script (iocBoot/iocFirewire/st.cmd) provided with areaDetector.

MEDM screens

The following show the MEDM screens that are used to control the Firewire detectors. Note that the general purpose screen ADBase.adl must be used to control many features, but it exposes some controls that are not applicable to Firewire cameras, and lacks many fields that are important for such cameras. A new Firewire-specific top-level control screen will be added in a future release.

firewireFeatures.adl is the screen used to control the features of Firewire cameras.

firewireFeatures.adl

firewireVideoFormats.adl is the screen used to control the video formats and modes of Firewire cameras. This is a screen shot when the camera is not in Format 7.

firewireVideoFormats.adl

firewireVideoFormats.adl is the screen used to control the video formats and modes of Firewire cameras. This is a screen shot when the camera is in Format 7, in which case the video rate menu is not displayed.

firewireVideoFormats.adl