A VLSI-FPGA system-on-Chip for detectors monitoring

In this paper we present a system-on-chip (SoC) designed to offer a self-contained, compact data acquisition platform for particle detector monitoring. With a companion ADC, this architecture is capable to acquire the detector´s signals, process the data and perform monitoring tests. The SoC is based on a custom, expanded version of a free, open-source 8-bit microprocessor. We extended the instruction set, added internal memory resources and integrated peripherals to interface the core with the external ADC. Peripherals implement in hardware threshold checking, pedestal suppression, waveform recording and a multi-channel analyzer. The SoC inherits from the open-source core some attractive features for real-time applications: high working frequency, constant instruction execution time, short and fixed IRQ latency and little logic resources requirement. The processor makes it possible to execute in software additional off-line data processing, such as averaging, FWHM calculation and peak finding. It includes an 8-bit I/O bus for interfacing with external logic and a UART for RS232 communications. We also present two implementations of the SoC: on a Virtex II Xilinx FPGA and on a standard-cell CMOS 0.18 mum ASIC. Their resource occupation and performance are compared, in the view of a deployment in the monitoring system of an experimental apparatus.