How to Choose a Logic Analyzer?

If you are in the market for buying or choosing a Logic Analyzer, how do you know which one is right for you? There are several options to select from and looking at the various technical specifications can be a daunting task. This article gives you some factors to consider when considering your purchase.

• Channel Count: The maximum number of digital channels supported by the logic analyzer. The more the channels the more debug capability. Typically a logic analyzer has around 8 Channels. It’s always good for logic analyzers to have more channels based on the complexity of the embedded design.
• Channel Bandwidth: This can be defined by the maximum frequency that can be measured by the logic analyzer.
• Sample rate: The Logic Analyzer needs to have the ability to capture glitches, setup, and hold time issues in the embedded design. Lowering the resolution of measurement by the logic analyzer, better the issues that can be captured in the design.
• Voltage Levels: The digital design comes with various logic levels. The Logic Analyzer needs to support logic families to debug the embedded system design. It’s always good to understand the voltage levels of the design and logic analyzer.
• Trigger Capability: A good Logic Analyzer can set complex and nested triggers. Understanding the trigger level and capability will help you select the right logic analyzer for you.
• Probe Type: The Logic Analyzer probes need to be easily connected to the design under test without creating any signal integrity issues.
• Capture duration: During complex engineering debugging a very long capture sequence is required to do the analysis. Hence having a very large capture can be an added
• Host Interface: USB 2.0 is the most commonly used interface for the logic analyzer some of them also have interfaces to the network using gigabit Ethernet.

Other Features to Consider:

• Support: Once you have the Logic Analyzer in your hand and run into issues during debug you will need a good team to support the debug issues in hand. Every company offers various levels of support.
• Shipping Lead Time: Once the logic analyzer is ordered the product needs to be shipped to the development location. Please check the lead times well in advance before ordering.
• Year of development: It’s always good to pick up a product that is stable in the market and used by many customers already.
• Ease of Use: Most of the Logic Analyzers are used to debug hard engineering problems and ease of use and integration into the development environment are very important features for the product.

Conclusion:

Shopping or choosing of Logic Analyzer can be a daunting task, and this guide will help you easily navigate the process of selecting the logic analyzer. As the number of channels to debug increases so does the cost of the product.

Prodigy offers Logic Analyzer which supports Real-time I3C Trigger & Protocol Analysis which enables engineers to debug timing, circuit-level, and system-level problems quickly. Advanced trigger, streaming, and unlimited data capture capabilities make it a must-have tool in your lab to debug I3C protocol.

Prodigy’s Logic Analyzer performs simultaneous protocol analysis of #I3C, #I2C, #SPI, #UART, #SPMI, #CAN/CAN FD, and #RFFE in embedded designs. Features such as 16 channels, 1GS/s Timing Speed, 2ns glitch Analysis & 100MHz state data capture make it an ideal must-have debug tool to address digital design problems. Designers can now easily analyze setup and hold time issues, glitches, and synchronous data activities apart from analyzing protocol issues.

A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or a digital circuit. It is an excellent tool for verifying and debugging digital designs. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, and assembly language. For debugging elusive, intermittent problems, some logic analyzers can detect glitches, as well as setup-and-hold time violations. During software/hardware integration, logic analyzers trace the execution of the embedded software and analyze the efficiency of the program’s execution. Some logic analyzers correlate the source code with specific hardware activities in your design.

Prodigy’s Logic Analyzer supports Realtime I3C Trigger & Protocol Analysis.

Why use a logic analyzer?

Debugging microprocessor-based designs required more inputs than what conventional analog oscilloscopes could offer. A typical logic analyzer has anywhere from 8 to 136 channels and they are particularly useful for looking at time relationships or data on a bus – for example, a microprocessor address, data, or control bus. They can decode the information on microprocessor buses and display it in a meaningful form.

A logic analyzer is used when we need to:

– Debug and verify digital system operation
– Trace and correlate many digital signals simultaneously
– Detect and analyze timing violations and transients on buses
– Trace embedded software execution

Types of Logic Analyzers:

There are three types of logic analyzers: Modular logic analyzers, Portable logic analyzers, and PC-based logic analyzers.

Modular Logic Analyzers:

Modular logic analyzers are the standard form seen in labs that have a chassis and multiple modules. These are one of the more expensive and provide the highest level of functionality to the user. Modules can be added or removed depending on the user to increase the functionality. Eg: Modules can be added to increase the number of channels in the Logic Analyzer depending on the user.

Portable Logic Analyzer:

Portable logic analyzers are more portable than modular logic analyzers and provide all the functions that are integrated into a single module with a screen. There may be instances when a smaller analyzer will be required due to restricted budgets or fields of service. These test instruments incorporate all elements of the analyzer into a single unit for ease of transportation.

PC-based Logic Analyzer:

PC-based logic analyzers are compact and they directly interface to a computer via an ethernet or a USB cable. The captured information is displayed to the user via the PC’s display. PC-based logic analyzers are the least expensive but are limited in terms of power compared to modular and portable logic analyzers.

Prodigy’s Logic Analyzer supports Real-time I3C Trigger & Protocol Analysis which enables engineers to debug timing, circuit-level, and system-level problems quickly. Advanced trigger, streaming, and unlimited data capture capabilities make it a must-have tool in your lab to debug I3C protocol.

Perform simultaneous protocol analysis of #I3C, #I2C, #SPI, #UART, #SPMI, #CAN/CAN FD, and #RFFE in embedded designs. Features such as 16 channels, 1GS/s Timing Speed, 2ns glitch Analysis & 100MHz state data capture make it an ideal must-have debug tool to address digital design problems. Designers can now easily analyze setup and hold time issues, glitches, and synchronous data activities apart from analyzing protocol issues.

<PRODIGY’S LOGIC ANALYZER

Evolution of Logic Analyzers: Future of Logic Analyzers in embedded system design

Traditionally Logic Analyzers are used to monitor parallel buses in microprocessors, microcontrollers, or PATA or memory interface-based designs. Data transfer between microprocessor and peripherals ICs is using the parallel bus. Programming of microprocessors or microcontrollers used to be in assembly language. To support debug digital design Logic Analyzers provided 100s of channels, advanced parallel pattern triggers, long acquisition memory, and disassemblers for different microprocessors and microcontrollers. Disassembler is additional hardware commonly called ‘PODS’ used to capture the data in microprocessor/microcontrollers IOs. Software associated with the POD is used to disassemble the captured data and display it in assembly language. This runtime assembly language code is used to provide great details enabling designers to debug and optimize the designs.

But modern electronics designs moved away from parallel bus design for good and adapted serial bus architecture for low-speed, high, and ultra-high-speed designs. Current digital designs are based on a system on a chip that has multiple low-speed and high-speed serial bus interfaces to support different design needs.  Data transfer between ICs or peripherals takes place using protocol using the serial bus. Product differentiation is driven by software features which continuously updated to add more capabilities. This has driven demand for a different set of capabilities in Logic Analyzer. To support these design needs Logic Analyzer does not need to be a high channel count but it should be capable of capturing data from multiple serial bus designs and displaying it in a time-correlated form so that designers can visualize the system-level operation. But just viewing the digital waveforms it is extremely difficult to interpret the serial data. Hence Logic Analyzer should provide multiple serial bus decoding capabilities. This simplifies the entire debug process.

Debugging any design is a very challenging activity. Designers need to find the root cause using the symptoms such as bus failure, boot failure, etc. Designers try to narrow down by eliminating different possible causes of the symptoms by looking at specific data and analyzing them. To get to the specific cause, the Logic analyzer should have the capability to define triggers on specific events or the ability to look for multiple events and take smart actions so that the root cause of the systems can be found.

This New generation Logic Analyzer supports the following capabilities.

• Good enough channel count (could be 10 to 32)
• Serial bus data analysis for different Protocols
• Simultaneously decode multiple Protocols
• Protocol-aware trigger capabilities
• Long acquisition support with pre and post-trigger capabilities

Prodigy Technovations offers Logic Analyzer to debug design in embedded system design. The logic analyzer is equipped to handle complex engineering problems.

Logic Analyzer for Embedded Interfaces

A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or a digital circuit. It is an excellent tool for verifying and debugging digital designs. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, and assembly language. For debugging elusive, intermittent problems, some logic analyzers can detect glitches, as well as setup-and-hold time violations. During software/hardware integration, logic analyzers trace the execution of the embedded software and analyze the efficiency of the program’s execution. Some logic analyzers correlate the source code with specific hardware activities in your design.

A logic analyzer is used when we need to

• Debug and verify digital system operation.
• Trace and correlate many digital signals simultaneously.
• Detect and analyze timing violations and transients on buses.
• Trace embedded software execution.

THE LOGIC ANALYZER

Debugging microprocessor-based designs required more inputs than what conventional analog oscilloscopes could offer. A typical logic analyzer has anywhere from 8 to 136 channels, and they are particularly useful for looking at time relationships or data on a bus. For example, a microprocessor address, data, or control bus. They can decode the information on microprocessor buses and display it in a meaningful form.

A logic analyzer measures and analyzes signals differently than an oscilloscope. The logic analyzer does not measure analog details. Instead, it detects logic threshold levels. When we connect a logic analyzer to a digital circuit, we are only concerned with the logic states of the signal, i.e., a logic analyzer looks for just two logic levels. When the input is above the threshold voltage (V) the level is said to be a “high” or “1”; conversely, the level below Vth is a “low” or “0”. When a  logic analyzer samples input it stores a “1” or a “0” depending on the level of the signal relative to the voltage threshold.

HISTORY OF LOGIC ANALYZER

Circuits started becoming smaller after the invention of the Integrated circuit (IC) in the early 1960s. While technology further developed over the years, there was an increase in the computational power and speed of digital circuits. Due to this reason, testing and debugging electronic devices proved to be difficult as thousands and millions of transistors could be packed inside a single chip which reduced their overall size and increased the number of pins. Hence, logic analyzers proved to be an important tool in analyzing electronic circuits due to their ability to time correlate a large number of signals on a single display which made it easier to view data movement and processing within many embedded systems or the peripherals of small computer systems.

Hewlett Packard announced the invention of the first logic analyzer in 1973 which was capable of measuring and displaying logic states across a set of LEDs. The HP 5000A was the first commercially available logic analyzer and had two channels.

TYPES OF LOGIC ANALYZERS

There are three types of logic analyzers: modular logic analyzers, portable logic analyzers, and PC-based logic analyzers.

Modular Logic Analyzers: Modular logic analyzers are the standard form seen in labs that have a chassis and multiple modules. These are one of the more expensive and provide the highest level of functionality to the user.

Figure 2. Modular Logic Analyzer

Portable Logic Analyzer: Portable logic analyzers are more portable than modular logic analyzers and provide all the functions that are integrated into a single module with a screen.

Figure 3. Portable Logic Analyzer

PC-based Logic Analyzer: PC-based logic analyzers are compact and they directly interface to a computer via an ethernet or a USB cable. The captured information is displayed to the user via the PC’s display. PC-based logic analyzers are the least expensive but are limited in terms of power compared to modular and portable logic analyzers.

Figure 4. PC-Based Logic Analyzer From Prodigy Technovations

ABOUT AUTHOR

Raghavendra Bhat is an Application Engineer at Prodigy Technovations. He graduated from NMAM Institute of Technology in 2020 with a bachelor’s degree in Electronics & Communication Engineering. His area of interest includes Embedded systems, Digital System Design, and Automotive Electronics.

For more information reach out to us at (contact@prodigytechno.com)

Debugging design in embedded systems is quite complex and Logic analyzers play a very important role to expedite the debugging and development cycle. Logic analyzers have a large number of channels that allow engineers to acquire many signals by connecting to a variety of test points on the DUT. Connections from the DUT to the logic analyzer are done using probes.

 A logic analyzer measurement is only as accurate and reliable as the probe of the logic analyzer. Selecting the right kind of probe is critical to the success of measurement and debugging of the DUT. The probe has an internal comparator in which input voltage is compared against the threshold voltage (Vth). The threshold value is user-defined, ranging from TTL levels to CMOS and ECL.

Hence selecting the right kind of probe allows for better design debugging. There are many kinds types of probes out in the market used to debug the design under test, the most commonly used being flying lead probes, multi-channel probes, and compression-type probes as shown below:

FLYING LEAD PROBES

Flying lead probes are general-purpose probes meant for point-to-point troubleshooting. Flying lead probes allow engineers to connect to a variety of wires, pins, and test points on the DUT and can be used for debugging in most applications such as IoT and low-speed interfaces in semiconductor chips.

Figure 1. Flying lead probes

HIGH-DENSITY MULTI-CHANNEL PROBES

High-density multi-channel probes require a dedicated connector on the DUT like a Mictor connector. High-density multi-channel probes are capable of acquiring high-quality signals with minimal impact on the DUT. High-density multi-channel probes are used in applications like JTAG for FPGA debugging. Along with JTAG, Mictor connectors are also used to debug trace signals like ARM CoreSight ETM.

Figure 2. High-density multi-channel probes

COMPRESSION PROBES

Compression probes use a connectorless probe attachment and are recommended for applications that require high signal density. The connectorless probe attachment allows for quick and reliable connections to the DUT. Compression-type probes are used for applications like JTAG for FPGA debugging and are also used to debug hardware trace signals like ARM CoreSight ETM.

Figure 3. Compression type probes

WHAT IS PROBE LOADING?

The impedance of the probes (capacitance, resistance, and inductance) plays an important role in the overall load on the DUT. All probes exhibit some loading characteristics.

The Discovery series Logic Analyzer comes with a set of general-purpose flying lead probes for point-to-point troubleshooting which allows the user to maintain high signal integrity and capture timing errors, analyze setup and hold time issues, glitches, and view synchronous data activities.

Figure 4. Logic analyzer for embedded interfaces.

ABOUT AUTHOR

Raghavendra Bhat is an Application Engineer at Prodigy Technovations. He graduated from NMAM Institute of Technology in 2020 with a bachelor’s degree in Electronics & Communication Engineering. His area of interest includes Embedded systems, Digital System Design, and Automotive Electronics.

For more information reach out to us at (contact@prodigytechno.com)