Nuts and Volts - June 2017

That Was Then, This Is Now

Good development tools no longer cost thousands of dollars, and many of the available microcontroller compilers are free. My first core set of development tools included a Heathkit oscilloscope, a Heathkit low frequency signal generator and an EICO VOM ( Volt-Ohm-Multimeter). My father believed that if I didn’t put it together, I didn’t know anything about it. So, the EICO VOM also was assembled by me by hand from a kit. I was obviously not set up to do any serious digital work. The closest I got to “digital’ was generating square waves with the signal generator.

After microcontrollers got my attention, I debugged with a logic probe and oscilloscope. The logic probe was used to see if an I/O pin was toggling or presenting a particular logic state. If I wanted to make sure my RS-232

baud timing or delay routine timing was correct, I would measure the timing using an oscilloscope.

You can still use a logic probe and oscilloscope to look at digital signals. However, thanks to the folks at Digilent, you can get the same and better results from a device about the size of a hockey puck that you can easily hold in one hand. Digilent’s Digital Discovery is an oscilloscope, a wave generator, a voltmeter, a logic probe, a pattern generator, and a protocol analyzer. I’m not going to elaborate on the Digital Discovery’s specifications here as they are available for your reading pleasure on the Digilent website. So, let’s put the Digital Discovery to work.

Virtual LEDs

The Digital Discovery operates under the control of Waveforms 2015, which runs on a PC. I’ve downloaded and installed Waveforms 2015 on my trusty Dell laptop. My Discovery is shown in Photo 1.

THE DESIGN CYCLE

Putting the Digital Discovery to Work

■ BY FRED EADY

46 June 2017

I love development tools. In the days of the dinosaur, development tools for microcontrollers were expensive and hard to come by. If you didn’t have $5,000 or more to spend, your bench didn’t see ANY development tools. It was so bad that when I began using PIC microcontrollers, I designed and coded my own set of hardware debugging tools. At that time — to add insult to injury — the PIC assembler cost $99. Instead of purchasing a license, I resorted to writing my own.

■ PHOTO 1. The Digital Discovery is based on a Xilinx FPGA and is capable of capturing digital signals in a number of ways at very high speed. This little box turns your PC into a multi-function digital test instrument.