Chapter 11. LabVIEW and Simple Microcontrollers

It was not too long ago that microcontrollers only handled digital I/O. Now, we are just celebrating the tenth anniversary of Arduino-compatible microcontrollers and a slew of other platforms such as Raspberry Pi that have A/D and D/A, memory, UART, USB, and I2C bus.

These open platforms have spun a huge industry that includes hundreds of add-ons called shield, which enhance the original capabilities of these microcontrollers. Combined with these microcontrollers and a fairly simple development environment, these boards have created capabilities for these products to be a test and possibly development platforms that may provide the functionality of the much more expensive DAQs. Obviously, simplicity and much lower monetary values of these platforms are exchanges made with precision, documentation, and inherent limitation of these devices.

An Arduino Uno Rev3, the most recent of Arduino products and compatible product families (known as shields...

DAQ devices versus microcontrollers

It is now almost over a decade and a half since microcontrollers have no longer been limited to digital I/Os. Mixed signals, control bus memory, separate timers, and counters have pushed their way into traditional microcontrollers with a speed that is only limited by the die size and functionality required, and most certainly price.

It is an undisputable fact that in data acquisition, speed and accuracy are directly related to the actual hardware and processors used and, depending on the speed and accuracy intended, a user must use proper hardware/software. In other words, proper instrumentation is the key to meaningful Data Acquisition. However, speed and accuracy at any given time in history have been relative terms. The terms high speed and accuracy have been highly relative throughout recent years and what we mean by speed and accuracy today is far different from what they meant just a few years ago.

Using the Arduino as a DAQ with LabVIEW

There are compelling reasons why a LabVIEW developer or tester may want to consider using these new low-cost microcontrollers (such as the Arduino family of products) as opposed to expensive (therefore, much more accurate) hardware:

• A vast area in development can be bypassed, at least in the early stages with off-the-shelf, less expensive, and open source hardware.

• Not everyone needs top-of-the-line, the fastest, or the greatest (at any given time), hardware.

• These platforms are by design, expandable, upgradable, and widely available. Supporting shields that are also widely available, if they can be used, drastically reduces development time.

• And the most compelling reason, as far as the subject of this book is concerned, is that National Instrument's LabVIEW has been supporting these products for many years now. In fact, the second generation of firmware/development the VI library, which supports these products, has been released under LINX 1.0

Installing the Arduino firmware

To use the Arduino family of products in general, one must install its firmware using Arduino development environment. The original Arduino development software is a text-based environment similar to many other traditional development environments. NI LabVIEW interface for Arduino ToolKit (http://sine.ni.com/nips/cds/view/p/nid/209835) originally opened the door to LabVIEW users to program directly in LabVIEW. Although very useful, this toolkit still requires installation of LIFA, by an external program to LabVIEW. Introduction of LINX has been a major improvement over the original Arduino ToolKit.