Friday, May 4, 2012

Sigrok: open source framework for logic analysers


While there are quite a few budget and even open source logic analyser platforms for recording and evaluating digital signals, each of them usually comes with a custom interface protocol and dedicated evaluation software of varying functionality. Usually, the software only works with one analyser family made by a specific company.

The Sigrok project, originally started by Debian developer Uwe Hermann along with Bert Vermeulen, aims to provide a uniform and platform-independent software environment for logic analysers. There are plans for a driver module that can be programmed with relative ease that will make the full range of features of the Sigrok framework, with its GTK, QT and command line frontends, available to analyser hardware products. However, according to its developers, the GTK interface is currently considered to be more stable than the Qt version.

According to the hardware overview, Sigrok currently supports nine analysers including the Open Bench Logic Sniffer, the Salae Logic analyser and the Bus Pirate. The source tree also offers a module for addressing ALSA sound cards. Additional modules are in development for several Cypress FX2-based analysers such as the USBee SX, for which Sigrok includes a firmware component. The ALSA module is expected to be completed in a future release along with analogue functions and GUIs, which are all currently at an alpha stage of development. The project's roadmap also includes unusual adapters such as the PICkit 2 programming adapter.

The current source tree (git clone git://sigrok.git.sourceforge.net/gitroot/sigrok/sigrok) offers decoders for protocols such as I²C, I²S, JTAG, LPC, UART, USB, and a few exotic ones like the Wii Nunchuck and the DCF77 protocols. However, the wiki states that most modules still offer incomplete support. The protocol decoders are written in Python.

Not all manufacturers will be happy about this development – some try to market the same hardware in different price ranges by adding software features. For $300 (£185), products such as CWAV's USBee Suite Pro offer additional protocol decoders and other essential extended features, as well as basic signal view navigation features, that are not included in the free version. However, a lot of work is still needed before Sigrok reaches a level that's comparable to that of commercial software and becomes a serious competitor, but it can already handle simple analyses.

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