Do You Need a Digital Pattern Generator?

Byte Paradigm, a company based in Belgium, conducted a survey of engineers who debug and test embedded hardware and software to determine the types of instruments used on their lab benches. It’s no surprise that oscilloscopes, logic analyzers, emulators, and JTAG probes came out on top for devices that help observe system behavior. The company also asked about devices used to stimulate an embedded system. Microcontrollers, general-purpose I/O lines, analog signal generators, JTAG probes, software emulators, and digital pattern generators (DPGs) gathered the most votes overall.

In a past life as a designer, I used small computers and I/O ports to create digital test signals and in one case I programmed an EPROM with about 1 Kbyte of digital patterns to stimulate a digital circuit and create serial bit patterns. But I never used a stand-alone digital pattern generator, perhaps because they didn’t exist at the time or they cost too much.

Many vendors sell PC-based pods that create and monitor signals on buses such as I2C and SPI. And instrument vendors such as National Instruments, Agilent, Tektronix, and LeCroy, offer instruments that generate patterns of bits. Byte Paradigm–the company that created the survey mentioned above–sells five types of DPGs controlled by a PC via a USB bus. (www.byteparadigm.com/)

Photo of the Wave Generator Xpress DPG from Byte Paradigm.

With that many vendors selling DPGs, engineers must buy quite a few. Unfortunately, I don’t know any of these people.

But I’d like to hear from those engineers who use or who have considered using a digital pattern generator. Do you think of a digital pattern generator as an essential lab instrument? Do you use one now and if so, what types of problems has it helped you solve or how do you use it to test circuits? If you don’t use a commercial DPG, how do you create digital test signals or patterns? –Jon Titus