Indian Journal of Science and Technology

Abstract

The objective of this work is to design and implement a custom reconfigurable JTAG controller in Verilog. It can be directly inserted in to a new digital IC designs with little modifications. It is fully compatible with IEEE 1149.1 standards. Additional programmable private instructions can also be added in to the design. A secure access mechanism is provided in to the controller which helps in protecting the system by preventing the un-authorized users from interfering with the system functions. A locking and opening mechanism and a password key based access control were incorporated as part of the JTAG controller module. The controller was configured to fit into different ISCAS’89 digital VLSI benchmark designs and results are analysed. It is observed that as the design size increases the area and power overhead decreases but the number of boundary scan vectors increases. All the designs were written in Verilog and RTL simulations were performed using Cadence NC-Sim Simulator. Cadence Encounter Test Architect 13.1 was used to check the boundary scan flow and analysis. A line graph to depict the power and area overhead is also shown. Complete performance analysis of the ISCAS’89 designs with and without the JTAG controller was performed. The power and area overhead was found to be negligible as the size of the VLSI designs increases.
Keywords: Access Control, Boundary Scan, JTAG Controller, Locking Mechanism, Programmable, Security, TAP