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New Capture Engine Features

The next few sections on captures explain how to update code for the old capture engine to code for the new capture engine.

The new capture engine includes additional support for "global" capturing (capturing the positions of multiple encoders from a single trigger). Global capturing is only global to a single SynqNet node. The reason for this is because position capturing is supposed to be a high-speed process, on the order of tens of nanoseconds. Communicating information across the SynqNet network would seriously degrade the timing of the capture engine.

The way the global capturing works is that an internal "global" bit is kept inside a node's FPGA. This bit is considered as one of the inputs into a capture's engine. Each capture also has the ability to link this bit to its trigger state. (Please see the Capture Engine Diagrams.) At any given time, only one capture may link to the global bit. One should not configure a capture to use the global bit as an input and then link to the global bit with the same capture.

In SynqNet Phase II MPI, instead of a trigger mask for capture, there is now an array of trigger sources, each with an enable and invert option. The following few sections will explain how this array functions.

The new capture engine supported by SynqNet Phase II MPI, also supports capturing on different edges of the trigger state. (Please see the Capture Engine Diagrams.) Capturing can now happen on the rising edge, the falling edge, or any transition of the trigger state. This is specified by the edge member of the MPICaptureConfig structure:

MPICaptureEdgeRISING Capture on the rising edge of the trigger state
MPICaptureEdgeFALLING Capture on the falling edge of the trigger state
MPICaptureEdgeEITHER Capture on an transition of the trigger state
MPICaptureEdgeNONE Never Capture

 

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