On-chip Instrument Access Through System Hierarchy

Abstract: There are many advantages with the development towards Integrated Circuits (ICs) with smaller, faster, and more transistors. However, tighter margins lead to a need of on-chip instruments to test, tune, and configure. These on-chip instruments, which can be in the range of thousands per IC, must be accessed through the life-time. However, access is challenged by complex system hierarchies. When ICs are mounted on Printed Circuit Boards (PCB) there might not be a direct access path and a single access protocol. In this thesis we have developed a generic module to handle communication between two ICs. We propose two alternatives for the communication. A hardware-based where communication is handled in an interrupt-driven manner and a software-based where the communication is handled through polling. We have made experiments using a Xilinx Field-Programmable Gate Array (FPGA) where we compare the solutions in terms of data overhead and area cost. We implemented two ICs on the FPGA where we for one IC used on-chip instruments connected using IEEE Std. 1687 and for the second IC we implemented our module connected using IEEE Std. 1687. The communication between the ICs was performed with Serial Peripheral Interface (SPI) and the communication with the outside world with Universal Asynchronous Receiver Transmitter (UART). The experiments show that the hardware-based solution provides little data and limited area overhead.