The MicroTCA acquisition and processing back-end for FERMI-Elettra diagnostics

During the construction and commissioning of the FERMI-Elettra Free Electron Laser (FEL) facility, tight requirements for diagnostics readout, processing, and control electronics had been specified; together with a complete integration in the main machine control system. Among the diagnostics devices to be controlled, the Bunch Arrival Monitors (BAM) and the Cavity Beam Position Monitors (C-BPM). The back-end platform, based on the MicroTCA (or uTCA) standard, provides a robust environment for accommodating such electronics, including reliable infrastructure features for slow control and monitoring of the electronics inside the crates. Two types of Advanced Mezzanine Cards (AMC) had been conceived, developed and manufactured in order to meet the demanding requisites. The first is a fast (160 MSps) and high-resolution (16 bits) Analog to Digital and Digital to Analog (A-D-A) Convert Board, hosting two A-D and two D-A converters controlled by an FPGA. The onboard logic is also responsible for service and host interface handling. The latter board is an Analog to Digital Only (A-DO) Converter, derived from the A-D-A, with an analog front side stage made of four A-D converters. Timing synthesis and distribution from a MicroTCA Central Hub (MCH) slot can be provided by means of a custom MicroTCA Timing Central Hub (MiTiCH), specifically designed for accurate (sub ps range) timing distribution over uTCA back-planes. The overall systems' architectures, together with the AMCs and MCH concept and functionalities, are described hereafter. A summary of the achievements, for each specific use case, together with our experience in the field with the new architecture, are then summarized. (authors)