The Tool Desk
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What is the Open Verification Library?
OVL is a library of assertion checkers intended for design, integration, and verification engineers. Accellera describes its purpose as checking for good or bad behavior in simulation, emulation, and formal verification. The library gives engineers reusable modules to monitor whether a design meets specified properties.
OVL’s working-group charter lists implementations or library materials in Verilog, SystemVerilog, VHDL, PSL, and SystemC. The OVL 2.0 manual describes checkers that combine a property with items such as a failure message, severity, and coverage information. Properties can be combinational—relationships evaluated within one cycle—or temporal, describing behavior across multiple cycles. Accellera OVL downloads · Accellera OVL working group
Can OVL be used for both simulation and formal verification?
Yes. The OVL manual documents a common, vendor-independent checker interface for design validation in simulation, hardware acceleration or emulation, formal verification, and semi-, hybrid-, or dynamic-formal flows. A checker can report a violation in simulation and its property intent can also be used as a target or assumption boundary in formal analysis.
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- The logic for each channel sampling rate of 24M/s. General applications around 10M, enough to cope with a variety ofoccasions; 8-channel
- Sampling rate up to: 24 MHz , can be 24MHz. 16MHz, 12MHz, 8MHz, 4MHz, 2MHz, 1MHz, 500KHz, 250KHz, 200KHz, 100KHz, 50KHz, 25KHz;
- The logic for each channel sampling rate of 24M/s. General applications around 10M, enough to cope with a variety ofoccasions;
- Input voltage range: -0.5V to 5.25V; Input Low Voltage: -0.5V to 0.8V; Input High Voltage: 2.0V to 5.25V
- Input Impedance: 1Mohm || 10pF (typical, approximate); Crystal: +/-20ppm, 24MHz
That reuse does not make a simulation run equivalent to a formal proof. In formal verification, engineers must define appropriate environmental constraints so that the analysis covers legal operating behavior and addresses the intended state space.
A practical checker workflow
- Define the rule. Turn a protocol, safety, range, handshake, parity, or temporal requirement into a property.
- Select and instantiate a checker. Use the matching
ovl_checker and connect its clock, reset, enable, and signal or property inputs as required by its interface. - Run simulation. Review failures, severity, diagnostic messages, and any checker coverage information.
- Set up formal analysis. Reuse the property intent, then constrain legal environmental behavior for the proof or analysis.
- Expand observability. Add checkers around relevant interfaces and corner cases where additional monitoring is needed.
These steps describe the methodology documented by Accellera; actual integration depends on the checker, HDL, and tools in the project.
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- 【High-Speed 8-Channel Analysis】Captures digital signals at up to 24MHz across 8 channels, enabling precise debugging of complex protocols like I2C, SPI, and UART—ideal for advanced STEM projects without the limitations of basic 4-channel models.
- 【User-Friendly Design】Base module and breakout board simplify connections to breadboards, microcontrollers, and other setups.
- 【Logic Level Expansion Board】Breaks out all 8 channels to 2.54mm male pins and pads for alligator clips, enabling flexible and secure connections in diverse projects.
- 【Logic Level Breadboard Adapter】 Easily connects the logic analyzer to breadboards, providing direct and convenient access to all 8 channels for prototyping and testing.
- 【Dual USB Connectivity】Comes with both USB-A and Type-C cables for universal compatibility with older PCs, modern laptops, and devices, ensuring hassle-free plug-and-play across Windows, Mac, Linux, and Ubuntu.
Which OVL checker should you use?
Choose the checker whose property matches the behavior to monitor, then confirm its precise semantics and ports in the OVL manual. The examples below identify rule categories, not specific checker names; the manual is the authoritative reference for selecting the exact module.
| Requirement | What the property should express | Integration point to verify |
|---|---|---|
| Handshake | Whether request, acknowledge, ready, or valid signals follow the required timing and response rules. | Clock, reset, enable, and the protocol’s permitted wait or response behavior. |
| Range | Whether a value remains within allowed minimum and maximum bounds. | Signal width, signedness, and whether the permitted bounds are inclusive. |
| Parity | Whether the data and parity bit or bits satisfy the specified parity rule. | Covered data width and the design’s parity convention. |
| One-hot | Whether exactly one bit in a vector is asserted, if that is the design requirement. | Vector width and whether zero-hot states are allowed at reset or in other states. |
How does OVL compare with SystemVerilog Assertions or PSL?
OVL provides a standard set of checker modules with a common interface; native SystemVerilog Assertions (SVA) or PSL may be a better fit when a team needs language-level expressiveness beyond the supplied checkers. The right choice depends on the property and the project’s verification stack, rather than on a universal portability claim.
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- 8 Digital/Analog inputs (multi-use)
- Decode SPI, I2C, and 23+ more analyzers
- Digital sample rate up to 500 MS/s, Analog sample rate up to 50 MS/s
- 10 Billion+ samples of digital, 500 Million+ samples of analog (uses PC memory, USB 3.0)
- Cross platform - Mac, Windows, & Linux
| Decision factor | What to assess |
|---|---|
| Portability | Whether the checker source and its semantics work across the HDL languages and tools the project targets. |
| Methodology reuse | How directly the property can be exercised in simulation, emulation, and the project’s formal engines. |
| Checker coverage | Whether the available modules cover the needed protocol, range, transition, parity, handshake, or temporal patterns. |
| Diagnostics and coverage | Whether failure messages, severity controls, and coverage reporting meet the team’s debugging and review needs. |
| Integration cost | How much work is needed for parameterization, reset and enable handling, and compatibility with the simulator and formal tools. |
For a rule that maps cleanly to a supplied OVL checker, the library can reduce the need to build a project-specific checker interface. For a more specialized temporal property, SVA or PSL may express the requirement more directly. Confirm behavior and support in the specific tool flow before standardizing on either approach.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What is the latest OVL version?
Accellera’s download page lists OVL 2.8.1 and shows a modification date of 2014-04-08. The separate OVL working-group page says the group is currently inactive and notes that OVL 2.8 was released in December 2013. These statements describe different aspects of the release record; the download page’s 2.8.1 listing is the version shown there, not evidence of a recent update. Check Accellera’s OVL download page · Check the working-group status
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- 16 channels dual-mode support: ①Stream mode captures and transfers data in real time for long sample duration; ②Buffer mode captures and stores data temporarily for high sample rate
- USB 2.0 Type-C interface with up to 16G sample depth in stream mode
- Support for adjustable threshold and shielded wires for a better, cleaner waveform
- 256Mbits on-board SDRAM memory with multiple buffer modes
- Compatibility with WinXP-Win10, macOS, and Linux, supporting nearly 100 protocol decoders, and being open-source on Github
Is OVL open source, and what license does it use?
Accellera’s statement of use says OVL 2.8.1 is licensed under the Apache License, Version 2.0, and that downloading the release constitutes acceptance of the stated terms. Read the official statement for the applicable legal conditions before using or redistributing the library. Accellera OVL statement of use
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