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    This module is included inLens: NSF Partnership in Signal Processing
    By: Sidney BurrusAs a part of collection: "LabVIEW Graphical Programming Course"

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    This module is included in aLens by: National InstrumentsAs a part of collection: "LabVIEW Graphical Programming Course"

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  • Lens for Engineering

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    By: Sidney Burrus

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  • eScience, eResearch and Computational Problem Solving

    This module is included inLens: eScience, eResearch and Computational Problem Solving
    By: Jan E. OdegardAs a part of collection: "LabVIEW Graphical Programming Course"

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Counters

Module by: National Instruments. E-mail the author

Summary: In this lesson, you will learn about counters.

A counter is a digital timing device. You typically use counters for event counting, frequency measurement, period measurement, position measurement, and pulse generation.

A counter contains the following four main components:

  • Count Register: Stores the current count of the counter. You can query the count register with software.
  • Source: An input signal that can change the current count stored in the count register. The counter looks for rising or falling edges on the source signal. Whether a rising or falling edge changes the count is software selectable. The type of edge selected is referred to as the active edge of the signal. When an active edge is received on the source signal, the count changes. Whether an active edge increments or decrements the current count is also software selectable.
  • Gate: An input signal that determines if an active edge on the source will change the count. Counting can occur when the gate is high, low, or between various combinations of rising and falling edges. Gate settings are made in software.
  • Output: An output signal that generates pulses or a series of pulses, otherwise known as a pulse train.

When you configure a counter for simple event counting, the counter increments when an active edge is received on the source. In order for the counter to increment on an active edge, the counter must be armed or started. A counter has a fixed number it can count to as determined by the resolution of the counter. For example, a 24-bit counter can count to: 2Counter Resolution1=2421=16,777,215 2 Counter Resolution 1 2 42 1 16,777,215

When a 24-bit counter reaches the value of 16,777,21516,777,215, it has reached the terminal count. The next active edge will force the counter to roll over and start at 0.

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Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

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