Using IEEE-1149.1 for in-circuit emulation

The author describes an in-circuit emulator based on using the IEEE-1149.1 JTAG port. This type of an in-circuit emulator virtually eliminates a number of the problems of the traditional ICE by eliminating the pod and the necessity for removing the processor from the target. Simultaneously with Corelis deciding that a JTAG based emulator would alleviate a number of very common problems, a number of semiconductor manufacturers decided to incorporate boundary-scan based debugging features into their chips. As more and more semiconductor manufacturers incorporate boundary-scan into chips, and as IC packages being introduced continue to have a lead pitch less than or equal to 0.5 mm, boundary-scan testing, probing, and emulation will continue to grow. As a replacement for a pod based emulator, boundary-scan emulators will continue to gain acceptance, particularly as developers realize that the physical limitations of probing some of the newer semiconductor devices preclude any other approach