March 1999, Issue 104

JTAG—Working with CoolPLD

THE NEXT STEP

Designing with JTAG-compliant parts doesn’t have to be difficult or expensive. Using reprogrammable devices may pay you back with dividends if you need to alter the logic later on.

Of course, Philips would love you to use their parts in your next board design, but suppose you need to use a combination of manufacturers’ devices. Shouldn’t be a problem, right? All JTAG-compliant devices can be used together, right? Right.

But, every reprogramable device has its own programming characteristics. So, the same programming algorithm the Philips programmer uses may not work with other manufacturers’ devices.

Engineers at Altera came up with an open standard to specify ISP programming for PLDs. Their Jam language should enable programming equipment vendors to get the data and programming algorithm in the same Jam file.

A Jam composer would create the JTAG chaining files, and a Jam Player would interpret the Jam file and program the targeted devices. Oh boy, universal tools!

Jeff Bachiochi (pronounced"BAH-key-AH-key") is an electrical engineer on Circuit Cellar INK’s engineering staff. His background includes product design and manufacturing. He may be reached at jeff.bachiochi@circuitcellar.com.