Build a Swiss Army Lab with Software Defined Instrumentation


It’s a safe bet that anyone who regularly reads Hackaday has a voltmeter handy, and chances are an oscilloscope isn’t far behind. But beyond that, things get a bit murky. We’re sure some of you have access to a good lab full of high-end testing gear, even if it’s only during office hours, but most of us have to make do with the essential due to cost and space constraints.

The perfect solution is a little magic box that could be whatever instrument you need at the time: some days it’s an oscilloscope, while others it’s a spectrum analyzer, or maybe even be a generic data logger. To keep things simple, the device wouldn’t have a physical display or controls of its own, instead you can plug it into your computer and control it through software. This would not only make the unit smaller and cheaper, but also allow for the creation of custom user interfaces that precisely match what the user is trying to accomplish.

Wishful thinking? Not enough. As a guest host Ben Nizette explained during the Software Defined Instrumentation Hacking Chat, the dream of replacing a rack of test equipment with an inexpensive handheld unit is much closer to reality than you might think. Although software-defined instruments may not be suitable for all applications, it could be argued that whatever capability the average student or hobbyist is likely to need or desire could be met by hardware already on the market.

Ben is a product manager at Liquid Instruments, the company that produces the Moku line of multi-instruments. Specifically, he is responsible for the Moku:Go, an entry-level device specifically designed for the education and maker markets. The slim device doesn’t cost much more than a basic digital oscilloscope, but thanks to the magic of software-defined instrumentation (SDi), it can replace eleven instruments, all of which are more than good enough for their target users.

So what’s the problem ? As you’d expect, that’s the first thing chat people wanted to know. According to Ben, the biggest downside is that all of your instrumentation has to share the same analog front-end. To keep it affordable, that means everything the device can do is bound by the same fundamental “speed limit” – which on the Moku:Go is 30MHz. Even on the company’s high-end professional models, the maximum bandwidth is measured in hundreds of megahertz.

Also, SDI was traditionally limited to the speed of the computer it was connected to. But the Moku hardware manages to circumvent this particular pitfall by running the software side of things on an internal FPGA. The downside is that some of the device functions, such as the data logger, cannot actually stream the data live to the connected computer. Users will have to wait until the measurements are complete before retrieving the results, although Ben says there’s enough internal memory to store months of high-resolution data.

Of course, as soon as this community hears that there is an FPGA on board, they want to know if they can get their hands on it. To that end, Ben says the Moku:Go will be supported by their “Cloud Compile” service in June. Already available for the Moku:Pro, the browser-based application allows you to upload your HDL to Liquid Instruments servers so that it can be built and optimized. This gives power users full access to Moku hardware so they can build and deploy their own custom features and tools that precisely match their needs without a separate development kit. Understanding that obsolescence is always an issue with a cloud solution, Ben says they’re also working with Xilinx to allow users to build on their own computers while implementing the proprietary “secret sauce” that makes it a Moku.

It’s hard not to be excited about the promise of software-defined instrumentation, especially with companies like Liquid Instruments and Red Pitaya bringing the cost of hardware down to the point where students and hackers can afford it. We would like to thank Ben Nizette for taking the time to chat with the community about what he is working on, especially given the massive time difference between Hackaday Command Center and Liquid’s Australian HQ. Anyone willing to jump online and discuss FPGAs and phase meters before sunrise is AOK in our book.

The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers to connect in a fun and informal way, but if you can’t make it live, these introductory articles along with the transcripts published on make sure you don’t miss anything.


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