Matrox Meteor-II /Digital grab section 67
Seven general purpose auxiliary signals are supported: four RS-422 or LVDS user signals (two input, two output), and three TTL output signals. These are available for controlling external devices, such as a strobe light. User signals are programmed using the MIL-Lite command MdigControl().
Two timers in the PSG can generate two exposure signals simultaneously. There are available in TTL or RS-422/LVDS formats. Exposures are programmed using the MIL-Lite function, MdigControl().
Three trigger inputs are routed directly to the PSG; the interface supports TTL and RS-422/LVDS trigger input. In addition, a trigger signal connected to the OPTOTRIG- and OPTOTRIG+ input pins, passes through an opto-coupler, a device that protects the board from outside surges; OPTOTRIG- is usually connected to the ground of the trigger source. This external trigger input allows image acquisition to be synchronized with external events. The board can operate in one of two modes, and the selected mode is specified by the DCF.
Matrox Meteor-II /Digital can operate in next valid frame/field mode When in this mode, the digitizer waits for the next valid frame or field (as specified by the DCF file) before commencing the grab. This trigger mode functions in one of three ways:
■Edge-triggered monoshot acquisition: The VIA (Video Interface Asic) waits for the rising/falling* edge to capture a single frame.
■Edge-triggered continuous acquisition: The VIA waits for the rising/falling* edge to start a continous grab.
■Level-sensitive "continuous" acquisition: The VIA grabs continuously while the level of the trigger is high/low*.
*The polarity of the active and inactive levels of the trigger signal are software programmable.
Matrox Meteor-II /Digital can also operate in asynchronous reset mode. In this mode, the digitizer resets the camera to begin a new frame when the trigger signal is received.
