Take that, Tektronix!?

By Brad Thompson, Contributing Technical Editor -- Test & Measurement World, 10/1/2010 12:00:00 AM

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In contrast to the pharmaceutical companies, test-instrument manufacturers rarely shower columnists with junkets, free lunches, pens and stationery, or generous samples of their wares. After all, purchasers of headache tablets outnumber test-equipment buyers by several orders of magnitude, and selling drugs is far more profitable.

Bereft of freebies, I finance my purchases of used and cheap test gear from my own pocket. When I stumbled across a brand-new, under-$100 portable storage oscilloscope, how could I resist?


Powered by a 3.7-V rechargeable lithium-ion battery, the DS0201's 2.8-in. color TFT LCD offers 320x240-pixel resolution. Controls comprise an edge-mounted on/off switch, two pushbuttons (pause/run and menu selection), and a four-way "joystick" pushbutton. The DS0201's innards consist of an ARM Cortex M3-compatible 32-bit microprocessor. Sample rate is 1 Msample/s, making this a 100-kHz oscilloscope with 12-bit resolution.

A miniature USB connector links to a computer and provides battery-recharging power, and an MCX coax connector provides the sole analog-input port. Hidden in an edge slot that would normally accommodate a camera-style wrist strap, a metal pin provides access to an internal 10-Hz-to-1-MHz square-wave generator.

To read past "Test Voices" columns, go to www.tmworld.com/testvoices.

Accessories include a 4-ft USB cable, a test probe with a 3-ft cable, and a permanently attached alligator-clip ground lead. Accessories include a removable "grabber" and a probe-tip insulator.

So, is this a "Take that, Tektronix!"-class instrument? Uh, no. Not at all.

There's no printed manual included (but see sidebar). Riddled with spelling errors (e.g., frequence (sic), paushed (sic)), the onscreen menu is enough to make this editor sic (sic).

Worse, there's no external sweep-trigger input connector. The scope that I purchased exhibited unstable sync, and the display flickered in its paushed, er, paused mode. The human interface needs a lot of improvement.

So, rest easy in Beaverton, fellas.

USBeastly Fortunately, the DS0201 is advertised as an "open source" instrument. Unfortunately, the "source" comprises a disorderly collection of files, including a user's manual: code.google.com/p/dsonano/downloads/list The "DSO_UI.rar" file describes the screen configuration, and the "DSO nano firmware generation and upgrade.pdf" file describes the required prerequisite files and how to use them. Be aware of typographical errors (e.g., DS"O" appears instead of DS"0"). You'll also need a post-Windows 98 PC with an available USB port and cable to reprogram the DS0201. You'll need the evaluation version of the IAR Embedded Workbench for the ARM processor; you can get a free download from IAR Systems: www.iar.com/website1/1.0.1.0/68/1 Return to the code.google.com site and download the latest "APP version." Next, go to the following URL to download the demo version of the DfuSe package, which will convert a HEX file into DFU (Device Firmware Upgrade) format for uploading revised code to the DS0201. Version 2.40 improves the user interface over the as-shipped Version 2.02. www.st.com/stonline/products/support/micro/files/um0412.zip For additional information about the ARM Cortex M3 processor, refer to: www.st.com/mcu/familiesdocs-110.html Once its "cute" factor wears off, you may find yourself wondering what the DS0201 might be good for. My hunch is that when reprogrammed, the device could serve as a dedicated built-in test indicator oscilloscope for in-house equipment. But it's a long way from serving as a general-purpose instrument.