FPGA developments for the SPARTA project

Abstract

The European Southern Observatory (ESO) and Durham University's Centre for Advanced Instrumentation (CfAI) are currently designing a standard next generation Adaptive Optics (AO) Real-Time Control System. This platform, labelled SPARTA 'Standard Platform for Adaptive optics Real-Time Applications' will initially control the AO systems for ESO's 2 nd generation VLT instruments, and will scale to implement the initial AO systems for ESO's future 100m telescope OWL. Durham's main task is to develop the Wavefront Sensor (WFS) front end and Statistical Machinery for the SPARTA platform using Field Programmable Gate Arrays (FPGA). SPARTA takes advantage of a FPGA device to alleviate the highly parallel computationally intensive tasks from the system processors, increasing the obtainable control loop frequency and reducing the computational latency in the control system. The WFS pixel stream enters a PMC hosted FPGA card contained within the SPARTA platform via optical fibres carrying the VITA 17.18/10 standard 2.5Gbps -1 serial Front Panel Data Port (sFPDP) protocol. Each FPGA board can receive a maximum of 10Gbs -1 of data via on-board optical transceivers. The FPGA device reduces WFS frames to gradient vectors before passing the data to the system processors. The FPGA allows the processors to deal with other tasks such as wavefront reconstruction, telemetry and real-time data recording, allowing for more complex adaptive control algorithms to be executed. This paper overviews the SPARTA requirements and current platform architecture, Durham's Wavefront Processor FPGA design and it concludes with a future plan of work.