Embedded Linux platform for data acquisition systems

Abstract

This scalable hardware–software system is designed and developed to explore the emerging open standards for data acquisition requirement of Tokamak experiments. To address the future need for a scalable data acquisition and control system for fusion experiments, we have explored the capability of software platform using Open Source Embedded Linux Operating System on a programmable hardware platform such as FPGA. The idea was to identify the platform which can be customizable, flexible and scalable to support the data acquisition system requirements. To do this, we have selected FPGA based reconfigurable and scalable hardware platform to design the system with Embedded Linux based operating system for flexibility in software development and Gigabit Ethernet interface for high speed data transactions. The proposed hardware–software platform using FPGA and Embedded Linux OS offers a single chip solution with processor, peripherals such ADC interface controller, Gigabit Ethernet controller, memory controller amongst other peripherals. The Embedded Linux platform for data acquisition is implemented and tested on a Virtex-5 FXT FPGA ML507 which has PowerPC 440 (PPC440) [2] hard block on FPGA. For this work, we have used the Linux Kernel version 2.6.34 with BSP support for the ML507 platform. It is downloaded from the Xilinx [1] GIT server. Cross-compiler tool chain is created using the Buildroot scripts. The Linux Kernel and Root File System are configured and compiled using the cross-tools to support the hardware platform. The Analog to Digital Converter (ADC) IO module is designed and interfaced with the ML507 through Xilinx Generic Interface (XGI) expansion headers. The Custom IP Core is designed and implemented in FPGA to interface the external ADC with DMA engine of the on-chip processor block. The data acquisition from ADC interface is successfully achieved and the captured data is sent to the host PC on mounted NFS share (Network File System) through LAN (Local Area Network). The detailed hardware and software design, development and testing results will be discussed in the paper.