I-V Curve Tracer Communication Protocol

Abstract

This thesis aims at developing a communication protocol for an I-V Curve Tracer. The IV Curve Tracer consists of a Raspberry Pi as the central unit to which a Source Measuring Unit (SMU) and a Relay Board is connected via USB and Ethernet, respectively. The SMU measures the I-V curve by generating a voltage sweep and measuring the resulting current. The relay board enables testing of multiple specimens. We include an Arduino Mega in this set up to accelerate the communication interface between the Relay modules and the Raspberry Pi. Therefore, our project aims to address the challenge of a scalable, low latency communication between the Pi-Arduino-Relay interface. Each Arduino is connected to one or multiple relay modules that are used to configure the interconnection between a single measurement device and various combinations of multiple PV cells in a current-voltage curve tracer (IVCT) testbed. This is significant because the time taken to complete a battery of tests using previous methods is over 15 minutes. However, an initial timing analysis found that the majority of the testing interval was spent on the communication to setup the relay configuration, not on the actual measurement process and hence, caused the relay boards to be slow to respond. This significantly limited the ability of the IVCT to scale-up in number of DUTs and complexity of interconnections tested. Our project seeks to overcome limitations of the current technology by significantly reducing the packet size of the transmitted data and eliminating the bloated and slow IoT platform. The expected outcome is a lightweight communication platform that is flexible and scalable with fast messaging not just for the IVCT testbed but also suitable for other research laboratory automation and control.