Nuts & Volts - July 2004

BY DUANE MATTERN

Lease Versus Purchase

There are many equipment leasing companies out there. Unfortunately, they rarely list prices or the details of their equipment on their websites. Also, most of the logic analyzers for lease are the big expensive monsters with lease prices in the order of $500.00/month. My requirements were only for 15 channels, possibly 12 months, and under $1,500.00. This pretty much ruled out the lease option — at least for the full-featured logic analyzer. So, I ruled out leasing and went shopping.

Shopping

Where do you do your shopping? When I’m looking for electronics, I typically look in past issues of Nuts & Volts Magazine before doing a search on Google. Once I have a product name, I’ll look in Google’s Groups to see if anyone has made comments (good or bad) about the equipment. I have seen a number of ads for PC-based electronic equipment that uses USB for communication. In fact, I have been involved with the development of such equipment using the ICs from FTDIchip.com From ads in Nuts & Volts, I knew that USB-based logic analyzers existed, so I started my Google search with the keywords, “USB Logic Analyzer.” That immediately brought up a number of items that I have summarized in Table 1.

Product Selection

All of the products in Table 1 would probably work for my application. From a software point of view, USBee looks neat because it has an application programmer’s interface, which could be used to expand its functionality. However, it only had eight channels and I needed 15. Also, it uses USB 2.0, which my PCs support, but I have not yet used it. The equipment from Link Instruments was pricey when compared to the other devices. I ruled out the Ant16 because I thought the buffer size of 2,048 samples/channel wouldn’t support my requirement of collecting data for several seconds.

I ended up selecting the DigiView DV1-100 device over the Janatek Lu LA-USB device because of the price and also because I hoped that the DigiView’s hardware data compression would allow me to look at long time sequences of the switching data. Also, Tech Tools was the vendor for the DigiView equipment and I’ve done business with them in the past.