原创 Reflecting on standards and travels

I was recently looking back at my first trip to Europe in 1992. We spent time in England, the Netherlands, Germany, Denmark, Sweden, Norway, and then Germany again and back to England over a three-week period. We slept on planes, boats, and trains.

We managed to pull off this trip before we had cell phones or the Internet. It was also before the euro, so we were constantly exchanging money as we left and entered countries. We also fumbled with some language translation books when trying to communicate with the natives; there were no apps yet or devices to use them.

The trip went very well. The only hiccup: We once got on a train going in the wrong direction. With the transportation infrastructure there, it didn't take too long to get back on the right track.

The trip got me to thinking about communications and standards. (I know, what an engineering nerd thing to do, right?) Actually, I confess that is a little backward. Thinking about the P1687 proposed IEEE standard brought the European trip to mind. Why is that?

The complexity of today's ICs is somewhat analogous to the complexities we encountered when planning and executing the trip. We had to deal with different travel methods, languages, currencies, and cultures in a condensed amount of time. Complex ICs contain many different parts and pieces that have to work together. These can include multiple power levels, on-chip clocks, tons of memories, CPUs, protocols, lots of IP (intellectual property and, in some cases, Internet protocol), sensors, and more.

IJTAG lets all IP speak the same language.

I work in the design-for-test area, so I can attest that finding a way to access, integrate, and test the different parts and pieces of an IC is quite a challenge. I believe that IEEE P1687 is a great help and enabler for designers and test engineers to accomplish their tasks. P1687, sometimes call IJTAG (the "I" stands for "internal") works along with the IEEE 1149.1 standard JTAG interface prevalent on most ICs. IJTAG is basically an IP and test procedure reuse methodology. It provides a general-access test mechanism to the embedded IP within all levels of the design hierarchy.

Having IJTAG compliant IP and test instruments in a design greatly simplifies complex test procedures. Test procedures or sequences written at the IP interface level can be remapped automatically to the top level of the design, regardless of where the IP sits in the hierarchy. All the IP throughout the design can be integrated into a test network that most efficiently completes the testing of all the pieces. In essence, using IJTAG compliant IP in the design means all the parts will speak the same language. Communication and productivity go up in a way similar to how the euro made it easier to travel among many European countries.

For a more detailed explanation of how IJTAG works, I encourage you to view this short video. If you really want to know the details of the IEEE P1687 proposed standard, then see the details.

Much as IJTAG can make IP access, control, and test easier, I expect my next visit to Europe to be easier now that we have cell phones, the Internet, apps, and the euro. I think I'll head for the southern countries, and it will be more of a relaxing holiday. It should be a breeze with the tools and standards now available.

Bruce Swanson
Technical Marketing Engineer
Mentor Graphics