Versatile Data Acquisition and Controls for EPICS using VME-based FPGAs

Field Programmable Gate Arrays (FPGAs) have provided versatile VME based data acquisition and control systems with minimal development times for the Thomas Jefferson National Accelerator Facility (Jefferson Lab). FPGAs have been used to interface with VME controllers using both standard A16 and A24 address modes. VME vector-interrupt capability has also been implemented for timing issues in some applications. FPGA designs have additionally been used to provide controls for various systems by interfacing with Analog to Digital Converters (DAC), interlocks, and other drive signals. These controls can be molded to the individual needs of each system and can provide operators with indicators and controls in EPICS via a VME interface. This allows the developer to choose components and make specifications that are not available commercially. Jefferson Lab has begun developing standard FPGA libraries that result in quick turnaround times and inexpensive designs. There have been approximately eight VME based FPGA designs implanted in one department at Jefferson Lab and they are becoming more widespread. FPGAs continue to become larger and faster enabling systems to be incorporated on one integrated circuit. Inherently, FPGAs can process data faster than many microprocessors due to the small processing overhead associated with a custom FPGA design. The ability to modify FPGA code enables the developer to easily implement future additions to a system, making the design flexible and expandable. This work supported by the U.S. DOE Contract No. DE-AC05-84ER40150