DS212 Oscilloscope Review: Open Source and Great for Hacking

We’ve seen plenty of oscilloscopes that look like repurposed cell phones. Usually, though, they only have one channel. The DS212, has two channels and a signal generator! [Marco] gives his review and a quick tear down in the video below.

The scope isn’t going to replace a big bench instrument, but for a portable scope with a rechargeable battery, it isn’t bad. The 1 MHz analog bandwidth combines with a 10 megasample per second front end and 8K of sample memory. The signal generator can produce basic waveforms up to 1 MHz. We were somewhat surprised the unit didn’t sport a touch screen, which is why you can see [Marco’s] fingers in the screenshot above. He seems to like the dual rotary encoder system the devices uses for navigation.

Where this really stands out is that it is open source for the the firmware running on the STM32 processor inside. We so rarely see this for commercially available bench tools and it makes this a fine hacking platform. It’s easy to imagine adding features like digital signals out and decoding digital data. It would be interesting to marry it with a WiFi chip and use it as a front end for another device over WiFi. Lots of possibilities. [Marco] shows that even though he’s not familiar with the STM32, he was able to add a custom waveform output to the device easily. This has the potential to be a custom troubleshooting platform for your builds. Lining up all of the sensing and signal generation settings for each specific type of test means you don’t need a guru to walk through the common failure modes of a product.

There are many small inexpensive scopes out there that might not match a big bench instrument but can still be plenty useful. [Jenny List] just reviewed one that comes in at around $21. And last year, we saw a sub-$100 scope that would net you just one channel scope. That’s progress!

Review: JYE Tech DSO150 Oscilloscope Kit

When men were men, and oscilloscopes were oscillographs.
When men were men, and oscilloscopes were oscillographs.

Do you remember your first oscilloscope? Maybe we have entered the era in which younger readers think of a sleek model with an LCD screen, but for the slightly older among us the image that will come to mind is likely to be a CRT-based behemoth. Mine was a 2MHz bandwidth Cossor from the 1950s, wildly outdated by the 1980s, but it came to me at no cost. It proudly proclaims itself as a “Portable Oscillograph”, but requires its owner to be a weightlifter to move it. I still have it, as a relic and curio.

For most of us a new ‘scope is still a significant investment. Even affordable current models such as the extremely popular Rigol instruments are likely to cost several hundred dollars, but offer measurement functions undreamed of by those 1950s engineers who would have looked on the Cossor as an object of desire.

Oscilloscope buyers on a budget may not have the cash for a Rigol, a Hantek, or any of the other affordable ‘scopes. Someone starting on the road of electronic engineering can scout around for a cheap or free second-hand CRT model, but thanks to the ever advancing march of technology they also have another option. Modern microprocessors and microcontrollers have analogue-to-digital converters and processor cores that are fast enough to provide the functions of a simple oscilloscope, and to that end a variety of very cheap ‘scopes and ‘scope kits have come on the market. These invariably have a rather small LCD screen and a relatively low bandwidth, but since they can be had for almost pocket-money prices their shortcomings can be overlooked in the name of value. It’s been a matter of curiosity for some time then: are these instruments any good? For around £16 ($21) and the minor effort of an online order from China, we decided to find out.

If you look at most stockists of electronic kits these days, you are likely to find an oscilloscope kit in their range. These are volume produced in China, and the same design trends appear across different models. You can buy surface mount or through-hole, and most of them feature a bare board with maybe a piece of laser-cut Perspex standing in for a case. There are one or two models appearing that come with a case though, and it was one of these that we ordered. The JYE Tech DSO150 is a single-channel ‘scope with a 2.4″ 320×240 pixel colour LCD screen and a 200kHz bandwidth. Its specification is typical of the crop of similar kits, though its smart case sets it apart and made it an easy choice.

In the Box

We ordered one, and when it arrived, it was packed in a small cardboard carton that had suffered some crushing in transit, but had protected the internal contents well enough that no harm had been done. A layer of foam protected the LCD, and the case parts appeared rigid enough to protect the rest of the components. There was a bag of discretes, the case parts, two PCBs, a test lead with crocodile clips, and two pages of instructions.

When looking at a kit, it’s best to start with the instructions, because no matter the quality of the kit itself it is the quality of the instructions that make or break a kit. If you can’t build it then it doesn’t matter how good it might be, it’s effectively junk.

The DSO150 instructions are two sheets of high quality double-sided colour print, with the emphasis on pictures rather than words, The front page introduces the kit and gives a quick soldering guide, then the next two pages step through each stage of construction. The final page has basic instructions for use, specification, and a troubleshooting guide. Our kit had all surface-mount parts already fitted, if we’d known the kit could also be had with SMD parts to fit we’d have bought that version instead.

Inside the DSO100.
Inside the DSO100.

The instruction steps are long on images and short on text, but there are sometimes few cues as to where the component in question lies on the board. Sometimes some careful examination of board and picture is necessary to ensure correct placement. The first step though doesn’t involve any soldering, wire the main board up to a 9V supply, and watch the LCD boot into the oscilloscope software. There is support via a forum on the JYE Tech website, we presume you’d go there if it failed to boot out of the box. A 9V PSU isn’t included, you’ll need to find one with a 2.1mm centre positive plug. Fortunately a suitable candidate was in the box of wall warts here, formerly being used by a router.

The main board assembly is straightforward enough, being the assembly of larger through-hole parts such as switches and connectors. The analogue board has a brace of small through-hole resistors and ceramic capacitors to fit, of these the resistors were of the tiny variety which made distinguishing between some of their colour stripes a little difficult. Bring your multimeter to check. There is a BNC connector that requires significant heat on there too, so make sure you have a suitably beefy iron to hand. Finally there is a small board for the rotary encoder, then the front of the case can be assembled to the main board, the analogue board attached, and the ‘scope set up. Verify on-board voltages, attach the test clip to the calibration output and adjust the compensation capacitors for a square wave, and the rest of the case can be added to complete the unit.

Functionality

The DSO150 showing the upper end of its bandwidth.
The DSO150 showing the upper end of its bandwidth.

In use, the DSO150 makes a simple and straightforward enough oscilloscope. The usual volts/division and timebase selection is easy enough, and the various trigger modes can quickly be selected. If you’ve used an oscilloscope before then you will have no problems getting started with it. But of course, the DSO150 isn’t just a simple oscilloscope, it’s a digital storage ‘scope. And with 1024 sampling points it can do the usual storage ‘scope thing of allowing the user to examine a stored waveform in great detail, scrolling back and forth through the stored points. Here the instruction sheet falls short, not mentioning that a double tap on the V/div or Sec/div buttons allows you to scroll.

Connecting the signal generator to our DSO150 allowed the exploration of its bandwidth. The claimed 200kHz is pretty spot-on, winding the signal generator far beyond that point showed a tail-off in displayed amplitude. Also the minimum 10µS per division limits the usefulness of a waveform display at these frequencies.

The DSO150 is supplied with a short test lead terminated in a pair of crocodile clips. This is somewhat less useful than the oscilloscope probes we’re used to, though happily it can also be used with a standard 1x/10x probe. Looking at the square wave on the test terminal through a standard probe reveals a sharp corner on the waveform, so there seems not to be any problems between the compensation on-board and that in the probe. It’s likely that either the DSO150 here will be used with a standard probe, or that the crocodile clip will swiftly be replaced with a probe of some kind.

Closing Thoughts

So then, the JYE Tech DSO150 oscilloscope kit. A nice little ‘scope within the limitations of the STM32F103C8 microcontroller that drives it. If you can put up with a 200kHz bandwidth and a 50V peak input voltage then it’s a useful pocket instrument. Its calibration will depend on the STM’s crystal and voltage reference, but as with the rest of its specification, when you consider its pocket-money price those become minor considerations. Add in that its software is open-source, and you have a very nice platform indeed. If we wanted to nitpick we’d ask for a battery compartment and a proper probe, but since both of those would put up the price we wouldn’t make too much noise about it. If you need a pocket ‘scope to supplement your bench scope when working on lower frequencies, or if you have a youngster in the family looking for their first ‘scope, buy one! Our review unit will definitely see some use rather than gathering dust.

Programming an Oscilloscope Breakout Game in Pure Data

[S-ol] wrote in to share his sweet breakout game played on an oscilloscope. Built in a weekend as part of a game development jam, Plonat Atek is a polar breakout game where the player attacks the center and the ball bounces around the perimeter. You can play it either on an oscilloscope or using an online emulator. [S-ol] wrote the game in Pure Data, a visual programming language for audio. The software controls the audio out channels and uses sound to control the game graphics. He also made use of the Zexy extension for Pure Data.

One of the cool things about this setup is that since the game is programmed with sound, all the sound effects also double as visual effects

We love oscilloscopes, and not just because they’re useful as hell. They also make sweet vector displays, like this analog pong game that uses a scope for a display. Even when they’re not being used for retrogaming they can be capable of some pretty amazing graphics.

Hybrid Interface Brings Touchscreen to Rigol Scope

With pervasive smartphones and tablets, the touch interface is assumed for small LCD screens, and we’ve likely all poked and pinched at some screen, only to find it immune to our gestures. Manufacturers have noticed this and begun adding touch interfaces to instruments like digital oscilloscopes, but touch interfaces tend to be an upgrade feature. But thanks to this hybrid oscilloscope touchscreen interface, even the low-end scopes can get in on the action.

It only makes sense that [Matt Heinz] started with one of the most hackable scopes for this build, which was his Master’s thesis project. Using an Android tablet as an auxiliary interface, [Matt] is able to control most of the main functions of the scope remotely. Pinching and expanding gestures are interpreted as horizontal and vertical scaling, while dragging the displayed waveform changes its position and controls triggering. While it’s not a true touchscreen scope, the code is all open source, so can a true aftermarket Rigol touchscreen be far away?

Rigol hacks abound here — you can talk to them in Linux, increase the bandwidth, or just get a look at their guts.

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Wireless Oscilloscope Review

[Martin Rowe] over at EDN recently put a $200 wireless oscilloscope to the test. The Aeroscope 100A is a single channel scope in a probe body that communicates back to an Apple smartphone or tablet via Bluetooth LE. You can see the video from the post, below.

The original prototype of the device had a high bandwidth, but the production model only manages to have a 20 MHz bandwidth at 100 megasamples per second: nothing earth-shattering.

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Part Soldering Iron, Part Hand-Held Oscilloscope

If you are in the market for a temperature controlled soldering iron, an attractive choice of the moment is the TS-100 iron available by mail-order from China. This is an all-in-one iron with a digital temperature controller built into its handle, featuring a tiny OLED display. It’s lightweight, reasonable quality, and all its design and software are available and billed as open source (Though when we reviewed it we couldn’t find an open source licence accompanying the code.) This combination has resulted in it becoming a popular choice, and quite a few software hacks have appeared for it.

The latest one to come our way is probably best described as coming from the interface between genius and insanity without meaning to disparage the  impressive achievement of its author. [Befinitiv] has implemented a working oscilloscope on a TS-100, that uses the soldering iron tip as a probe and the OLED as a display. It requires a small modification to the hardware to bring the iron contact into an ADC pin on the microcontroller, and there is currently no input protection on it so the iron could easily be fried, but it works.

It is strongly suggested in the write-up that this isn’t a production-ready piece of work and that you shouldn’t put it on your iron. At least, not without that input protection and maybe a resistive divider. But for all that it’s still an impressive piece of work, a working soldering iron that becomes a ‘scope on a menu selection. Take a look at the ‘scope-iron in action, we’ve posted a video below the break.

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Playing Mario on an Oscilliscope

Any display can be connected to a microcontroller and used as a display if you know the protocol to use and have enough power in your micro. Sometimes, an odd display is used just “because it’s there.” This seems to be the case for Reddit user [phckopper], who has used a STM32 and a PS2 joystick to play a version of a Mario game on an oscilloscope.

There’s not many technical details but [phckopper] lets us know that the rendering is done using the SPI on the STM, transferred via DMA, which is synchronized to two saw-tooth waves that are fed in to the X and Y axes of the oscilloscope.  The Z axis, which controls the brightness of the dot, is fed from the MOSI. By making the oscilloscope range all over the screen, similar to the way a CRT’s gun does, [] is able to draw sprites, rather than vector graphics. The display has a resolution of 400×400 and each sprite is 16×16. The input is from a PS2 joystick connected to [phckopper]’s PC, with the information communicated over UART using a simple protocol.

We don’t get to see much of the game in the video after the break, but it’s a pretty impressive job nonetheless, especially when you realize that [phckopper] did this project when he was just sixteen! There are a couple of other oscilloscope projects here at Hackaday, like this one, a great version of pong played on the ‘scope, or this one, showing off some great graphics.

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