I have testes several logic analyzers (both commercial and DIY) and software for them. I would like to see on this Open Source world is some kind of common format logic analyzer data presentation and maybe common API for accessing the information. In this way it would be easy to write all kinds of applications that decode data and hardware that captures the data independently. I would want something like what Wireshark did for network traffic analyzing – open source and easily expandable software.
Not I think I have found one software that seems to match those needs, and it is called sigrok.
When sigrok project started, the developers focused on logic analyzers because those devices used to be expensive. Nowadays heap FX2-based boards that work with sigrok can be had for as low as $15, and there is even hardware specifically sold for this software. The scope has expanded as Sigrok can also handle analog signals and the developer consider any kind of test and measurement equipment in scope of the project; “if it can be queried or controlled, we’ll take it on“. Nowadays sigrok is a software suite for extracting data collected by various types of analyzers and displaying them or analyzing them using protocol decoder plugins.
The sigrok project aims at creating a portable, cross-platform, Free/Libre/Open-Source signal analysis software suite that supports various device types. At the current state sigrok is a portable, cross-platform, free open source signal analysis software suite that supports various device types, such as logic analyzers, MSOs, oscilloscopes, multimeters, LCR meters, sound level meters, thermometers, hygrometers, anemometers, light meters, DAQs, data loggers, function generators, spectrum analyzers, power supplies, IEEE-488 (GPIB) interfaces, and more. It supports a wide variety of hardware and many protocol decoders (new decoders can be written in Python).
- libsigrok: a library written in C that standardizes access to different test and measurement devices. libsigrok is a shared library written in C, which provides the basic hardware access drivers for logic analyzers and other supported devices, as well as input/output file format support.
- libsigrokdecode: a C library that provides an API for protocol decoding. The decoders are written in Python 3 and later.The libsigrokdecode library ships with a collection of various protocol decoders out of the box (but you can write your own too, of course; see Protocol decoder HOWTO and Protocol decoder API for details).
- sigrok-cli: a command line interface to manipulate sigrok.
- PulseView: a Qt GUI to manipulate sigrok.
- Fx2lafw: sigrok also provides an open source implementation of the Cypress FX2 chip firmware, which is used — among others — by Saleae in all versions of its logic analyzers except the logic Pro 16. This firmware can program the embedded logic to function as a single logic analyzer hardware.
I write in this article mostly about PulseView and sigrok-cli. They at downloadable for Linux, Windows and OS X from http://sigrok.org/wiki/Downloads. This video introduces how to use sigrok PulseView: Cheap logic analyzer + Sigrok pulseview = timesaver (LHT00SU1)
I decided to test sigrog on Windows. Sigrok provides nightly Windows installers for sigrok-cli and PulseView. PulseView is a Qt based logic analyzer, oscilloscope and MSO GUI for sigrok. PulseView can record signals from suitable device and display then nicely on the screen. PulseView software provides also decoders for many popular types of communication protocols including UART, CAN bus, I2C, SPI, JTAG, PWM, etc.
For initial testing I used first the Demo device, that generates semi-random signal you can look at without need for any hardware. I did the first tests with this Demo signal.
To be able to record real world signals, I need some supported hardware that can capture signals. Luckily I had several hardware that should be suitable. First I tried PulseView Windows to work with 8 logic channel Saelae clone device. It worked pretty much “plug and play” when I just plugged it in and selected to use FX2-based boards driver fx2lafw: Sigrok found the device with the drivers I had in my computer.
Next I tried to do the same with with USBee AX clone, that should be compatible (I think), but did not work “plug and play” as PulseView failed to find it. It seems that it would need some more work with the drivers. At the moment I did not want to mess up with the drivers as described at How to use it with PulseView (I think I would risk compatibility with some other software doing that). Maybe some later time.
Next I tried RGB LED decoder with signal captured from my WS2812 addressable LEDs test circuit.
PulseView has a quite good list of supported protocol decoders (PDs) as the libsigrokdecode library ships with a collection of various protocol decoders out of the box. If that is not enough for your special needs, you can write your own too, of course; see Protocol decoder HOWTO and Protocol decoder API for details. Every protocol decoder is a Python module and has its own subdirectory in libsigrokdecode’s decoders directory. Protocol decoder HOWTO offers a minimalistic example of how a protocol decoder looks like.
Related articles on signal analysis:
Signal analysis using Sigrok blog posting tells how to install Sigrok on Ubuntu and and capture signals with command-line utilities.
Rocking with sigrok article gives introduction to using sigrok commant line tools in Linux.
Logic analyzer: visualizing latency between two digital signals in real time with sigrok and matplotlib tells how to manipulate data extracted fromlogic analyzer with Python, to view the latency between two digital signals
Sigrok: Using Logic to Debug Logic presentation slide set from Linux Foundation event gives introduction to usign sigrok
Information on logic analyzer hardware options:
fx2lafw is an open-source firmware for Cypress FX2 chips which makes them usable as simple logic analyzer hardware. The fx2lafw firmware is meant to work on any FX2-based hardware, including logic analyzers, FX2 eval boards, or other hardware which has this chip on-board.
How to use it with PulseView article tells how to use cheap “USBEE AX” logic analyzer with PulseView on Windows (tells the tricks how to configure Windows drivers).
Hobby Components low cost 8 channel logic analyser was first dedicated hardware for sigrok. Together with sigrok’s PulseView or sigrok-cli (command line version) software you can capture up to 8 digital logic channels at sample rates up to 24MHz.
Arduino logic analyser article tells how you can turn Arduino Uno R3 board to open logic sniffer compatible device (that should be supported with sigrok). You need code from .
A BeagleBone Logic Analyzer article tells that BeagleLogic realizes a logic analyzer on the BeagleBone Black using the Programmable Real-Time units and matching firmware and Linux kernel modules on the BeagleBone Black. BeagleLogic Turns your BeagleBoard into a 14-channel 100Msps Logic Analyzer page tells that with the sigrok project, BeagleLogic gets support for software triggering and decoding a large variety of digital communication protocols.
Related postings in this blog: