Digital I/O Fundamentals

1. Fundamentals of Digital I/O

	Voltage Levels are what define how a device determines a valid logic state (logic high level or logic low level). Learn more »
	Logic Families (Single-Ended versus Differential) are groups of logic circuits with standardized voltage levels that constitute a voltage high or low level. All circuits within a logic family are compatible with other circuits within that family because they share the same characteristics. Learn more »
	Clocked Digital I/O Generation, Acquisition, and Compare are digital operations where binary data is sent or received from a digital device to a device under test (DUT) across multiple pins/channels. Learn more »
	Termination is an important principle to understand when designing high-speed digital so that you can maximize signal quality and minimize the effects of signal reflections. Learn more »
	Industrial Digital I/O Features include isolation, higher voltage levels, programmable power-up states, change-of-state detection, watchdog timers, and industrial certifications. Learn more »

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2. Common Terminology and Definitions for Digital I/O

Digital Definitions

• Jitter
• Skew
• Rise time and fall time
• Overshoot and undershoot
• Settling time
• Hysteresis
• Duty cycle

Digital Concepts

• Creating digital vectors/waveforms (8-min. demo)
• Double Data Rate (DDR)
• Eye Diagram Analysis
• Benefits of deep onboard memory

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3. Examples of Digital I/O Applications

Device Verification/Characterization

• Bit Error Rate Testing (BERT) (7-min. demo)
• Digital-to-Analog (D/A) Converter Testing (4-min. demo)
• Logic Analyzer
• Mixed-Signal Test (webcast)

Functional Test Applications

• Memory Testing (6-min. demo)
• Voltage measurements with a digital device
• Open and shorts
• Stuck-at-fault tests
• Diode testing

Interfacing with Digital Devices

• Digital protocols (JTAG, I²C, and SPI)
• Interfacing with ECL devices
• Interfacing with LVDS devices
• Customizing Digital Communication Interfaces

Industrial Applications

• Using a Magnetic Encoder for Anti-Lock Braking
• Using a Flow Sensor in Semiconductor Manufacturing
• Optical Isolation in a Chemical Pigment Mixing
• Change Detection in a Power Plant Monitoring

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4. Choosing the Correct NI Digital I/O Device for Test, Control, and Design

National Instruments provides a wide range of digital I/O (DIO) products with different speed, voltage, and timing options to meet the digital needs of your test, control, and design applications. Check out the resources below to determine which product line offers the ideal feature set for your application.

• Digital I/O for Test, Control, and Design
• Digital waveform generator/analyzers (high-speed digital I/O)
• Industrial digital I/O
• Reconfigurable digital I/O
• Counter/Timer I/O