Seeed Studio DSO Nano
I recently purchased a DSO Nano from Little Bird Electronics, partly because I like tech toys, partly because it is an open source device, meaning that I have access to the software and hardware details, and partly because it looked like it could be a quite useful piece of test equipment.
The DSO arrived within 48 hours of order, thanks to the prompt service from Marcus and Maddy at Little Bird Electronics. One thing I really like about Little Bird Electronics, is the way they package their goods for transport. That is they pack items into reusable storage containers, so not only do you get great products from them, but get free storage bins for all your goodies, or if chef of the house discovers them they may be assigned to kitchen duty.
On opening I found DSO, a soft case for the DSO, and two leads, one with small clips, ideal for connecting to the ends of through hole components, and test pins, the other lead had pins instead of clips, and I found these to be ideal to plug directly into the expansion sockets of an Arduino board.
The first thing I noticed about the DSO Nano, was its’ size, it was smaller than I had visualised, however the display is excellent, and as such the size is no problem whatsoever.
Being battery powered makes for a very convenient device, as that means one less cable lying around to get in the way. On switching on the battery was close to fully charged, and after the usual sort of boot screen, the unit is ready to run. There is no user manual included with the DSO, however it can be downloaded from here. There is however, a flap inside the box that describes all the buttons and their functions. Having read that, then using the DSO is very easy.
The biggest limitation of the DSO is its’ input bandwidth which is 1 MHz. Useful tasks that it do are things like observing RS232 data lines to confirm correct operation, One wire transfers between an arduino and a peripheral such as a DS18B90 an SPI line to the ethernet shield or an I2C line to another peripheral. Of course audio monitoring is a given. See the accompanying pictures for examples of the display.
When the DSO first powers up the settings default to Auto trigger, 1Volt per division on the Y axis, 200uS per division on the X axis, Y position 2.4 Divisions from the bottom, Trigger sensitivity at 5.6 and 6.1 divisions, positive slope, x1 probe scale, 1kHz output, Time cursor 2 at 3/4 scale, time cursor 1 at 1/4 scale, and trigger voltage at 2.4 Volts. These settings are suitable to see almost any waveform, before adjusting the controls for clearer display.
The Y sensitivity is adjustable from 10mV per division to 10V per division on the x1 range and 0.5V to 100V per division on the x10 range. The steps follow the normal 1, 2, 5 sequence. I noted that on the 10mV range there is about 1/3 of a division of a square wave at 10 kHz visible. While this would cause problems when trying to view very small signals, in a digital environment, it won’t cause any problems at all.
Horizontal sweep speeds between 10S per division and 1uS per division are available. Changing the sweep rate on a captured signal does not change the captured signal, it only changes subsequent captures.
There are 6 different trigger modes, Auto, Normal, Single, None,Scan and Fit.
Auto, Normal, and Single all performed very well, easily locking the incoming waveform.
None of course had no triggering, and gave a rolling waveform, Scan, which I have never seen before, scans the timebase up, so that the waveform width varies across the screen. Finally Fit works most of the time to produce a display that shows around 2.5 repeats of the incoming waveform at about 60% of the screen. On one occasion however, the Fit function failed to set up properly, and basically hit the stops at 0.1 V per div and 10uS per division on a 5KHz 4V P/P square wave.
There are two horizontal and two vertical cursors that enable the user to measure the amplitude and time between the cursors. Also there is a dedicated frequency readout at the top of the screen.
The vertical adjustment allows the user to place the trace anywhere on the screen as desired. Horizontal positioning is adjustable, and the trigger point can be moved from the fourth division to the about 10 screens beyond the screen edge, thus allowing you to view a considerable distance past the trigger point. This adjustment is really only a trigger holdoff for a variable period of time. A bargraph at the bottom of the screen indicates where the display is relative to the trigger point.
I guess this could be classed as a bonus, as it is not usual on dedicated scopes. It is limited in that it has fixed level out, and only a limited number of frequencies. But having said that, it can provide a clock to a project, or if you set the Atmel fuses wrongly, you could use it to provide the clock while you reprogram the fuses to enable the internal oscillator.
During my initial use, I seem to have been able to get 5 or 6 hours of use before it needs charging, which is excellent. Plugging it back into your computer or a USB style plug pack will recharge it in around 3 hours, this means you could get a reasonable days work from it and charge in the evening.
I made several attempts to write and read from a 2GB microSD card, and even though I created a file as suggested I was not able to save a waveform. According to the manual, you can download a file and put it in the root directory of the card, but in the limited time I had I was unable to find the file. I will attempt to get waveform saving working shortly, and if I am successful, I will update this review.
This is not the best DSO on the market, but it is the cheapest I have seen. For what it does, it is exceptional value, it is small, easy to use and will provide very useable results at a price less than a good dinner for two. There is little on the down side, and lots on the up side. I am giving it a score of 4 out of 5 stars, mice, thumbs – whatever rocks your boat.
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