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Lab Bench Clear-Out: Compact Logic Analyzer and More

Lab Bench Clear-Out: Compact Logic Analyzer and More

Technology Editor Bill Wong takes a hands-on look at a compact logic analyzer, a handwriting calculator app, and sewable electronics.

My Lab Bench has been piling up with stuff to check out, and I needed to clear some space for new stuff. The latest crop includes an economical, compact logic analyzer, a new version of my favorite calculator app and some sewable electronics kits. These will appeal to new developers and makers.

Tiny Logic Analyzer

IKA Logic sells a number of low-cost, USB-based logic analyzers and oscilloscopes. I took a look at their top end, 149€, SQ200 logic analyzer (Fig. 1). This 4-channel logic analyzer has a 200-MHz sampling rate and can capture up to 4 Msamples per channel. The system also will operate in a mixed capture/generate mode using a digital pattern generator to drive one or more connections. Of course, you need to trade off inputs and outputs among the four connections.

1. IKA Electronics’ SQ200 is a four-channel logic analyzer that captures up to 4 Msamples/channel at 200 MHz.

The SQ200 has support for adjustable input/output voltage and adjustable input resistance, and outputs can support open drain with an optional pull up. Input protection is ±35 V. The system can also handle two differential pair inputs.

These all work with IKA Logic’s ScanaStudio (Fig. 2). It runs on Microsoft Windows, Linux, and Apple’s Mac OS.

2. The SQ200 and its siblings work with the ScanaStudio.

Less-expensive versions are available with fewer inputs, smaller capture buffers, etc. The top end supports the widest range of trigger options including edge detection, level change, pulse, pattern, and serial protocol such as I2C, SPI, RS-232, CAN, 1-Wire, and JTAG. It was easy to use ScanaStudio to trigger on patterns like I2C address and CAN frame IDs. The protocol support is open source and available on GitHub.

Getting started with ScanaStudio and the SQ200 for basic capture and generation was relatively easy, since the number of options is significantly less than high-end logical analyzers. Still, for microcontroller projects, platforms like the SQ200 are more than sufficient and significantly less expensive.

The ScanaStudio interface was easy to use and has a good complement of time-measurement-related features, as well as protocol analysis and presentation. The Signal Overlay feature is interesting—it allows for editing of captured streams to see how changes affect timing. This can be handy for creating data streams to be sent as output streams.

In addition, the system can be extended using JavaScript, although I didn’t have a chance to write any of my own code. Users can suggest features and new features are made available to ScanaStudio users.

The signal-generator script build IDE is actually used to create Javascript functions that generate signals. For example, it’s possible to create a transaction for an I2C slave device using the SQ200 without having a microcontroller manage the transaction. This can be handy for testing devices or scenarios. The scripts can generate error logs and messages, which is useful for regression testing.

Overall, the system is very flexible and really limited by the capture rate. It’s more than sufficient for microcontroller work, easily handling low-speed serial protocols.

Improved Handwriting

I’ve taken a look at some of MyScript’s handwriting technology in previous articles. It’s Nebo editor uses MyScript’s Interactive Ink. It works best with a tablet and pen. The Calculator app is free and runs on tablets and smartphones that work with Android and iOS.

3. MyScript Calculator 2 supports limited equation-solving abilities as well as multiple expressions.

MyScript Calculator 2 (Fig. 3) is the latest addition. It adds a significant number of features compared to the original app, which enabled you to write arithmetic expressions that were then solved. Unfortunately, the app only lets you do one at a time. Calculator 2 makes it possible to write multiple expressions on the screen, and thus it’s easier to remember results. It also allows chained modifications, such as extending an existing expression.

The new version retains a history of calculations. They can also be exported as text or as an image. The system is moving toward spreadsheet-like functionality with the ability to handle time-order independent calculations of multiple sub-equations on a page. Edit a value and the system changes the results from related equations accordingly.

Calculator 2 works well on an iPhone, but a tablet provides more workspace for more complex calculations. Though more detailed work is best with a pen, fingers work just fine in most instances.

For now, Calculator 2 is available for Apple users. Android users still have version 1.x available for free. Try out whatever version your device can handle. It’s much quicker than using a calculator app.

Sewable Electronics

I didn’t actually test out Sparkfun’s sewable electronics kits, but I looked at them before giving them out at my presentation on wearable electronics. I had mentioned some of the other kits I gave away there, but didn’t have time to write up these until now.

They included the $49 Sparkfun LilyPad ProtoSnap Plus Kit (Fig. 4) and the $99 LilyPad Sewable Electronics Kit. They are both based on LilyPad USB Plus microcontroller that has an ATmega32U4 microcontroller that works with the Arduino bootloader. The USB connection is for programming and debugging. A 110-mAh lithium-polymer (LiPo) battery powers the system. The more expensive kit includes additional devices.

4. Sparkfun’s LilyPad ProtoSnap Plus Kit is intended to be used for the creation of wearable technology.

The system is essentially a small board designed to be sewn into a garment and connected to small displays and sensors like the LilyPad Light Sensor, LilyPad Buzzer, LilyPad Button Board, LilyPad colored LEDs, and a LilyPad Slide Switch. These devices are connected to the microcontroller using uninsulated wire that can be easily threaded through fabric. The voltage and current is minute, so the potential issues tend to be things like unwanted shorts if wires are sewn too close together.

The wearable technology was developed for Sparkfun by Dr. Leah Buechley, who now runs the design firm, Rural/Digital. Dr. Buechley was also associate professor at the MIT Media Lab. There she founded and directed the High-Low Tech group. An online activity guide is designed to get developers started with wearable projects.

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