Diligent OpenScope MZ
A great platform-agnostic analysis tool for electronic education, but note its limited bandwidth
SCORE ✪✪✪✪✪ PRICE £66 (£81 inc VAT) from digikey.co.uk
When taking your first steps in the field of electronics, there are only a handful of tools you need: a good screwdriver, a passable soldering iron and a cheap multimeter. However, while you can diagnose a wide range of problems with such a multimeter, eventually you’re likely to need more - and that’s where an oscilloscope comes in.
Where a multimeter allows you to take an instantaneous reading of a signal voltage at a point in time, an oscilloscope allows you to track and display changes over time. As with multimeters, oscilloscopes range from the cheap to the extremely expensive - with a far higher upper end than multimeters.
The OpenScope MZ is a novel take on the concept. The creation of Digilent, it’s a flat circuit board with none of the usual features of an oscilloscope present: there’s no display for the graph, no BNC connector for a probe. Instead, it’s designed for use with Digilent’s WaveForms Live software, which runs in the browser of any modern PC, tablet or smartphone.
Aside from its rather spartan design, there are a couple of other aspects that make the OpenScope MZ stand out. First among these is that it’s an entirely open design: Digilent has published the circuit design files, firmware, source code et al under a permissive licence, claiming a desire to “enable everyone to learn electronics”. That statement then reveals the second point of interest: the OpenScope MZ is a tool for education and hobby use, not professionals.
That’s not to say it lacks features. The OpenScope MZ and the WaveForms Live software are surprisingly powerful, including not only dual-channel oscilloscope functionality but also the ability to act as a single-channel function generator, 10-channel logic analyser, and even a low-voltage programmable power supply.
It’s the specifications that relegate the OpenScope MZ to the classroom rather than the lab: at 2MHz with a 6.25 million samples per second (MS/ sec) sample rate, it can’t compete with rival designs such as the SainSmart DDS-120 at 20MHz.
For education and hobbyist use, though, a 2MHz bandwidth limit is barely an issue. Following a short setup process on a Windows, macOS or Linux-based machine, the OpenScope MZ can be connected to a local Wi-Fi network or configured to act as a Wi-Fi hotspot; once configured you can connect to and control the device from any machine, including tablets and smartphones, without additional software.
For those used to using an oscilloscope on the end of a short
“Digilent has created a simple tutorial that covers connecting the OpenScope, configuring it and taking a measurement”
tether, Wi-Fi connectivity will likely come as a revelation. While the bundled probe cable takes some getting used to – rather than a pointed pen-like probe with a BNC connection on one end, the OpenScope MZ uses a multicoloured cable ending in 30 female pin headers that can be used with 2.54mm-spaced pins or solderless breadboards and left plugged in hands-free during use – being able to leave a device on test running while you sit at a comfortable desk looking at the results on a big screen is wondrous.
The software itself is a pleasure to use, too. Based on Digilent’s standalone WaveForms 2015, the open-source WaveForms Live makes it easy to use the device’s various functions - to the level of allowing connection to a simulated OpenScope MZ, allowing the user to experiment and learn before having to splash out any cash on the device itself.
That said, those making the move to an OpenScope MZ as their first oscilloscope will need to spend some time becoming acclimatised. The flexibility of the device translates into a range of menu options that can confuse initially – the concept of a “trigger” being the first to get your head around – but Digilent has created a simple tutorial that covers connecting the OpenScope MZ to a system, configuring it, updating the firmware to the latest version, calibrating it – a simple and entirely internal process that requires no external function generator or signal source – and taking a measurement from the in-built function generator.
As an educational resource, the OpenScope MZ is easy to recommend. As a hobbyist’s tool, the OpenScope MZ’s suitability depends largely on whether 2MHz of bandwidth is enough for your needs. For lab use, only the device’s relatively low cost gives cause to purchase it over more powerful, though closed-source, rivals.
SPECIFICATIONS 200MHz PIC32MZ processor 512KB RAM microSD slot 802.11g Wi-Fi 30-pin GPIO flywire probe kit cables WaveForms Live software 1yr RTB warranty. Oscilloscope functions: two channels, 12-bit, 2MHz, 6.25MS/sec sample rate. Function generator functions: one channel, 1MHz, 10MS/sec update rate. Logic analyser functions: ten channels. Power supply functions: 50mA, ±4V.