Tag Archive | "FFT"

The world’s smallest oscilloscope??

Hello readers

Today we examine a tiny and fascinating piece of test equipment from Gabotronics – their XMEGA Xprotolab. Sure, that sounds like a lot – and it is. Yet the functionality of the Xprotolab is inversely proportional to its physical size. Try to imagine having an oscilloscope, arbitrary waveform generator, logic analyser and a spectrum analyser – including a display – in a package no larger than 25.4 x 40.6 mm (1″ x 1.6″) in size. Well imagine no more as here it is:

1ss

As described above, this tiny marvel of engineering has the following functions:

  • Two analogue oscilloscope channels with a maximum sampling rate of 2 million samples per second;
  • Analogue bandwidth of 320 kHz at 8-bits resolution;
  • Buffer size of 256 samples;
  • Fast fourier-transform;
  • Analog and external digital triggering;
  • Maximum input voltage of +/- 10V;
  • Automatic average and peak-to-peak measurements;
  • Logic analyser with eight channel maximum simultaneous monitoring;
  • Firmware is user upgradable;
  • Can also be used as a development board for the XMEGA microcontroller (extra items required);
  • When powered from a USB cable, the board can supply +/-5V and +3.3V into a solderless breadboard.

The OLED screen is very clear and precise, which considering the size of 0.96″ – very easy to read. One can also set the display mode to invert which changes the display to black on white, bringing back memories of the original Apple Macintosh:

invertedss

Using the Xprotolab took a little getting used to, however after pressing menu buttons for a few minutes I had it worked out. The more sensible among you will no doubt read the instructions and menu map listed at the website. Having the dual voltmeter function is quite useful, it saved me having to mess about with a couple of multimeters when trying to debug some analogue circuits I’m currently working with.

The display can be as complex or as simple as you choose, for example when working with the oscilloscope you can disable one channel and shift the waveform so it occupies the centre of the screen. Or when working with the logic analyser, you can choose to only select the channels being monitored, instead of filling the screen with unused logic lines.

There are a couple of things to take care with. When inserting the Xprotolab into your breadboard, be careful not to put pressure on the OLED display when pushing down; when removing it from the breadboard, try and do so evenly with the help of an DIP IC puller.

Generally in my reviews there is a video clip of something happening. Unfortunately my camera just isn’t that good, so below is the demonstration clip from the manufacturer:

As you can see the Xprotolab would be quite useful for monitoring various signals whilst prototyping, as you can just drop it into a breadboard. Furthermore, if your required range is measurable the Xprotolab saves you having to look back-and-forth between a prototype and the display from a regular oscilloscope as well.

As the purchase price is relatively cheap compared against the time and effort of trying to make an OLED display board yourself, one could also plan to build an Xprotolab into a final design – considering a lot of measurement and display work is already done for you it could be a real time-saver. The Xprotolab can run from a 5V supply and only draws a maximum of 60 milliamps. Product support is quite extensive, including source code, schematics, videos, a user forum and more available from the product page.

In conclusion the Xprotolab is genuinely useful, inexpensive and ready to use out of the box. It would make a useful piece of test equipment for a beginner or seasoned professional, and also integrates well into custom projects when required.

Remember, if you have any questions about the Xprotolab,  please contact Gabotronics via their website.

[Note – the Xprotolab reviewed in this article was received from Gabotronics for review purposes]

Posted in gabotronics, oscilloscope, part review, review, xmega, xprotolabComments (8)

Review – Ikalogic SCANALOGIC2 Logic Analyser/Signal Generator

Hello Readers

Today we will take a first look at the Ikalogic “Scanalogic2” PC-based logic analyser and signal generator. This is a tiny and useful piece of test equipment that should be useful for beginners and experienced engineers alike. It has been developed by two guys in Europe that are dedicated to the craft, and I wish them well. First of all, let’s pull it out of the box and see what we have:

contentssss

Upon opening the box, one finds a USB cable, the connector leads and the unit itself. It really is small, around 60 x 35 x 20mm. The USB cable is just under 900mm long. Finally a small instruction and welcome postcard which details a quick overview of the software and the unit’s specifications. Ikalogic are to be congratulated for the minimal level of packaging – finally a company that realises one can download the required items instead of printing books, burning DVDs and causing an increase in shipping weight.

The first thing you will need to do is download the latest software. It needs a Windows-based PC with .net framework. Installing took about two minutes, then the ubiquitous system restart. Finally the last preparation is to check for the latest firmware and update it. This is a simple procedure – download a .zip file, extract the .hexe file, then just file>update device firmware in the software. The desktop software checks for new versions before every startup, so you can be sure of having the latest version.

Here are the specifications of the unit from their web page:

specs

Certainly there is a lot there to take advantage of. Personally I consider the logic analyser functions to be of great interest, and will now demonstrate those to see how they can be useful in debugging and generally figuring out what my designs are up to.

One can capture data in two ways, either by using a live sampling mode, or capture mode where you set the device to sample data into its memory, and then reviewing the data using the software. If you are using the live mode, the quality of the sampling will be affected by your PC resources. For example, consider this first demonstration. A very simple Arduino is setting a pin high and low:

demo1ss

In live mode you can still use the horizontal scroll feature to move backwards and forwards through the captured data. One can also expand the data display to the full width of the window. When using the live mode, I found that there was still some variation in the logic levels that was not programmed for. My PC is fairly up to date, consisting of an AMD PhenonII dual-core 3.1 GHz CPU, 2GB RAM at 1066 MHz, running Windows 7 x64. Perhaps I could use some more RAM? A better video chipset? Who knows… Unfortunately I don’t have a more powerful PC to test. Therefore I will stick to the normal capture mode. Doing so is also quite easy – here is the basic setup tab:

It is pretty self-explanatory. If you have a fair idea of your sampling rate, you can drop it down to increase the available sampling time. Here I have selected the lowest sampling rate, as I will just capture the pulses as shown in the earlier demonstration. Once your sample has been collected, you can scroll through it at your leisure, and also save the sample to disk.

In being able to save the data for later retrieval, there are three things that can be done with the data:

  1. As anyone can download the software, you can share your samples by emailing or sharing the files with colleagues – they can playback the sample without owning a Scanalogic themselves, by just using the software;
  2. You can keep the sample for later analysis
  3. You can blast out the captured data using the function generator feature. Neat! Let’s do that now…

Earlier on I captured the following from an Arduino board:

demo3ss

And now I can just right-click on the data (channel one) and select run data generator for this channel then click start on the left. Which results in the following output:

Very good (except for my old CRO). Also notice the log area at the bottom of the application screen – it relays unit status, error messages and so on. Now let’s capture and look at some more interesting sample data. The following example is an example of captured data from an Arduino serial-out pin, which was programmed to send the letter “A” out at 2400 bps using serial.write();

uartdemoss

Once you have captured the sample, you can select the parameters of the data stream and decode the sample. As you can see in the image above, the decoder shows the data stream in hexadecimal and the ASCII equivalent.

Next on the test is I2C. This is a common two wire data bus from Philips/NXP, used in many systems. More about I2C with Arduino is here. A very popular example of an I2C IC is the Maxim DS1307 real-time clock. We can use our Scanalogic to eavesdrop on the SCA and SCL data lines to see what is being said between the microcontroller and the DS1307:

i2cone

So in the example above, the value 0x68 (binary 1101000) is sent down the bus. This is the unique identifier (slave address) for a DS1307 IC. So the Arduino is saying “Hey – DS1307 – wake up”. This is then followed by a 0x00 or directional bit. The DS1307 then replies by sending the time data back to the bus. The first piece of data in the reply is 0x68, which identifies to the I2C bus (recall that 0x68 is the DS1307 identifier) that the data is from the DS1307. Following this is the time and data data in hexadecimal, which is converted to binary-coded decimal in the microcontroller software.

When working with I2C, it really pays to have the data sheet for your IC with you. Then you can decipher the data, direction and timing with the sample data on one side and the timing diagrams on the other. For example, page twelve of the DS1307 data sheet. In doing so, it reminds me how much I dislike I2C 🙂

Moving along. Next we will have a look at some data from the SPI (serial peripheral interface) lines. Again, this is quite simple, you just connect the four hooks into the clock, MOSI, MISO and CS lines, and capture away. The software allows you to select which hook is connected to which line, so you can connect up quickly. At this point I will note that the IC hooks are somewhat inexpensive, and the designers could have spent a few more Euro on including some decent ones. Anyhow, here is the screen dump:

spidemo

At this point one can realise all sorts of monitoring possibilities. I wish I had one of these years ago when learning digital electronics – you could just monitor the highs and lows over four channels and debug things very quickly. Will keep this in mind when I get around to making a TTL clock.

Anyhow – the Scanalogic2 has a lot going for it in terms of data capturing ability, the price is right, you can update the software and firmware very easily, and the desktop software is freely available in order to share samples with others. There are a few cons though – the IC hooks could be better (I couldn’t connect four in a row onto an IC for the life of me); the unit could use some documentation in terms of a “Getting Started” guide or webpage – so due to this the learning curve is quite high. There is their version here, but I feel it could be expanded upon. Many beginners and amateurs will be attracted to this unit due to the price. However there is a support forum and so on, but answers can vary in quality and time. However, don’t let the cons put you off – this thing is cheap, the software is very good – and it works. Two thumbs up!

To purchase a Scanalogic2, visit the Ikalogic home page. If you need to analyse some data, and don’t want to spend a bucket of money – this is for you.

Posted in ikalogic, product review, review, Scanalogic, test equipmentComments (4)


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