General purpose RISC based unit: a building block for fast data acquisition systems

The development of a fast, modular and distributed data acquisition system for a large number of parallel channels is based on the design of a building block which will be presented in this paper. The small format of this unit (3"×4"), achieved through the use of surface mount components, makes it a powerful and versatile plug-in board for the realization of numerous RlSC embedded, data acquisition system functions. Some examples of applications are the SCSI interface for a protein crystallography detector, and the acquisition board, crate controller and CAMAC optical link interface boards. The board consists of an IDT R3081, up to 2 MB static RAM, up to 1 MB of EPROM, 2 serial ports, a 16-bit timer and all the necessary glue logic implemented in an AMD MACH231. One feature that makes this module suitable for data acquisition applications is the fast 32-bit external bus interface. It allows the implementation of fast data transfers, histogramming and LUTs. On-board address decoding provides up to four external chip select lines. Support for quad-reads is included, which result in up to 64 MB/s data transfers on the external bus (128 MB/s for SRAM access). Four synchronized interrupt inputs and a large instruction cache also makes the board suitable for fast demanding real time applications