![]() ![]() In normal operation these boundary scan cells are invisible. The process of boundary scan can be most easily understood with reference to the schematic diagram shown in figure 1.Īll the signals between the device’s core logic and the pins are intercepted by a serial scan path known as the Boundary Scan Register (BSR) which consists of a number of boundary scan ‘cells’. The main advantage offered by utilising boundary scan technology is the ability to set and read the values on pins without direct physical access.įigure 1 – Schematic Diagram of a JTAG enabled device ![]() This standard has retained its link to the group and is commonly known by the acronym JTAG. The findings and recommendations of this group were used as the basis for the Institute of Electrical and Electronic Engineers (IEEE) standard 1149.1: Standard Test Access Port and Boundary Scan Architecture. In order to overcome these problems, some of the world’s leading silicon manufacturers combined to form the Joint Test Action Group. ![]() IntroductionĪdvances in silicon design such as increasing device density and, more recently, BGA packaging have reduced the efficacy of traditional testing methods. However, you do not need to know this in order to use XJTAG’s products, because XJTAG testing operates at a higher level which does not require knowledge of the detailed workings of JTAG. This document provides you with interesting background information about the technology that underpins XJTAG. XJDirect - Programming on-chip flash in your processor. ![]()
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