Distributed I/O Tier: from concept to operational readiness – a modular platform for custom radiation-tolerant and radiation-free electronics

The Distributed I/O Tier (DI/OT) project was launched to develop a common, modular hardware platform for custom electronics at the lowest layer of the CERN control system. Traditionally, this layer—closest to the accelerator and often exposed to radiation—relied on highly specialized, custom-designed devices with little reusability across subsystems. DI/OT addresses this limitation with a 3U crate based on the CompactPCI Serial industrial standard, along with high-performance (non-radiation-tolerant) and radiation-tolerant (lower-performance) modules. Key components include two System Boards (featuring Igloo2 FPGA and AMD Zynq UltraScale+ MPSoC), a radiation-tolerant switched-mode power supply, a fan tray, an FMC WorldFIP module, and a radiation-tolerant RISC-V soft-core. DI/OT users can tailor the platform to their needs by designing application-specific Peripheral Boards, FPGA configurations, and low-level software for the System Board. Standardizing on a common platform enables different equipment groups to benefit from centrally supported hardware while facilitating the sharing of application-specific peripherals. Over the past few years, DI/OT has evolved from a prototype to a production-ready platform. This paper presents DI/OT’s hardware modules, radiation qualification results, initial pilot deployments at CERN, and its adoption by the quantum computing community. Keywords: DI/OT, custom electronics, CompactPCI-Serial, SoC, radiation-tolerant