Analog!

Since the sigrok project started, we’ve focused on logic analyzers. They were the initial inspiration for the project, and were at that time just getting affordable — at least compared to the bad old days when such gear cost thousands of dollars. Since then, prices have continued dropping and capabilities have increased; the Openbench Logic Sniffer is just $50, and will happily sample at 100MHz. Cheap FX2-based boards can be had for as low as $15. But logic analyzers were never the limit of our ambition. sigrok groks your signals for you — ALL your signals! We 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.

To that end, we’ve recently merged in support for processing analog data, as well as the first driver using it. The driver is hantek-dso, and supports the Hantek DSO-2090 USB oscilloscope. It’s part of a series of five similar models, all of which we plan to support. The only output module supporting analog data for now just outputs voltage levels as text, suitable for importing into other tools.

Capture from a DSO-2090, before postprocessing, as plotted by qtiplot

We will, of course, also support saving analog data in .sr files. If you know of any other file formats that are commonly used for transferring oscilloscope output, do let us know! We’re always happy to put it on our TODO list, and even happier to take patches.

We also have a Hantek DSO-5200A, a higher-end model in the same series, so it will be supported quite soon. We can’t buy every device out there, however, so we will need help if we’re going to support the DSO-2150, DSO-2250 and DSO-5200. If you own one of these, you can help! Opening up your device and taking pictures of the internals for the wiki is already a great step forward; helping us to test the driver on a model we don’t own ourselves is even better.

Detailed pictures of the PCB and components should also help us to determine what exactly the difference is between these models. We know the 2xxx series share the same firmware and most of their specifications, for example, so the difference is likely in the analog frontend only. But is it possible to do a simple upgrade from one model to another? This is not unheard of; in the case of the Rigol DS1052E and the Hantek 5062B bench oscilloscopes the hardware is identical to higher-end models.

Next on the agenda are drivers for the Link Instruments MSO-19 and the PoLabs PoScope. The MSO-19 in particular is a very popular device, and both are interesting for us in that they’re Mixed Signal Oscilloscopes (MSOs): they can output both analog and digital signals. We can handle both separately, but getting them at the same time — and keeping them in sync — is another challenge entirely.

Several of the FX2 boards we support also have analog frontends; we plan to add support for these to the fx2lafw firmware and driver both.

We’re also in the planning stages of support for other devices that output various kinds of analog data. More on that later, watch this space!