Dedicated Software & Hardware Configurations

• Dedicated software and hardware configurations are integrated systems that precisely map physical and digital resources to specific workflows for deterministic execution and fault resistance.
• They employ specialized FPGA firmware, atomic configuration workflows, and tight error-handling protocols to achieve ultra-low latency and robust diagnostics.
• Rigorous validation and control mechanisms ensure configuration integrity and operational safety in high-risk, real-time environments like accelerator or autonomous systems.

A dedicated software and hardware configuration is an integrated set of hardware platforms, firmware, and software stacks designed for a specific application domain, optimizing system behavior, rigor, and operational safety under defined real-time constraints. These configurations are engineered to couple tightly the functional logic, error handling, control protocols, and user-interface layers in complex systems—such as particle accelerators, embedded robotics, scientific DAQ setups, or autonomous vehicles—so that each physical or digital resource is mapped explicitly to its associated workflow or control task. This precise mapping aims to yield deterministic execution, configuration control, and resilience against both transient faults and operational misconfiguration.

1. System Architectures and Hardware Domains

Dedicated system architectures partition hardware into functional domains aligned with control flow and application requirements. A canonical example is the PIP-II Machine Protection System (MPS) at Fermilab, which realizes strict failure handling and mode-dependent channel logic via multiple FPGA-based subsystems:

• Main MPS (MPSM): Implements the central permit-generation logic on a Xilinx FPGA, communicating over up to 20 single-mode fiber channels (ACLK/LCLK timing, bidirectional control) and aggregating up to 80 I/O channels for direct Beam Inhibit Devices (BIDs).
• Analog MPS (MPSA): FPGA board with dedicated BlockRAM-based threshold LUTs and up to 40 analog channels (via 10 × 4-channel 125 MSps ADCs); performs real-time analog comparison against mode-dependant thresholds.
• Digital MPS (MPSD): Hosts serialization logic (8B/10B encoding, LVDS fiber) to aggregate^16 TTL digital signals into high-throughput permit inputs, managed per mode with LUT masks/high/low values.
• Beam Inhibit Devices (BIDs): Tiered hardware elements for rapid beam shutoff, mapped directly to hardware I/O for both fast faults and redundant hard-fault conditions.

An ASCII interconnect diagram from the MPS exemplifies the physical channel flow among ADCs, MPSA, MPSM, and BIDs, overlaid with Ethernet-based EPICS IOCs acting as the software control and monitoring interface (Carmichael et al., 31 Jan 2024).

2. Software Stack and Configuration Control

The software layer orchestrates the control logic, configuration state, and user-interface, focusing on deterministic behavior and prevention of live errors. For PIP-II MPS:

• FPGA Firmware: Hard real-time execution for permit decisions, state transitions (STANDBY, READY, BEAM_ON), LUT-indexed filtering, and tiered inhibition logic. Run-to-completion semantics with a fixed period $t_{update} \approx 33$ ns and maximum permit shutoff latency $t_{latency} \le 10\,\mu$s.
• EPICS IOCs: Linux-hosted process servers provide networked access to FPGA registers, status flags, trip logs, and expose controls for configuration management and diagnostics.
• Middle Tier (DPMs): Java services mediate REST, Protocol Buffers, and Channel Access between IOCs and GUIs; enforce schema-level validation and invariant protection of mode tables.
• Expert Configuration Apps: Mode/mask/limit table editing with atomic push to block-RAM in "No-Beam" mode, coupled with authentication and preflight validation.
• Operator Interfaces: Phoebus (display/UI) for authenticated mode change; Flutter apps for post-mortem trip analysis and register snapshotting.

These layers are organized to prevent configuration drift, enforce live state invariants (e.g. injectors not maskable), and ensure atomicity and auditability of all control events before beam enablement (Carmichael et al., 31 Jan 2024).

3. Firmware Logic: Real-Time Decision and Fault Handling

Hard real-time operation is achieved via state machine firmware and LUT-indexed mode logic:

• State Machine: Encodes {STANDBY, READY, BEAM_ON} in VHDL; transitions are triggered by mode events, configuration done signals, beam_enable commands, and trip detection.
• LUT-Based Filtering: For both analog and digital channels, pass/fail is computed per sample (digital: state equals expected or masked; analog: sample within bounds or masked). LUTs indexed by (OperatingMode, ChannelID).
• Fault Handling and Recovery: Pipelined tiered inhibition (Tier-1, Tier-2) on fail detection, with 10 μs escalation delay. Fault counters with auto-reset windows, supporting both auto and operator-initiated recovery.
• Timing Guarantees: Decision update period is $33$ ns; cumulative latency across pipeline stages never exceeds $10$ μs:

$$t_{latency} = \sum_{i=1}^{N_{pipeline}} t_{stage,i} \le 10\times10^{-6}\,\text{s}$$

• Error Diagnostics: Link-level CRC, per-channel fault counters, and trip timestamp FIFOs for IOC-archived diagnostics.

4. Configuration Management and Validation Mechanisms

Mode configuration management relies on a central repository and transactionally atomic workflow:

• Configuration Repository: Stores (BeamMode, MachineMode, BID_ID) mappings to enabled channels, polarities, and thresholds.
• Load/Activation Sequence:

1. Operator selects target mode via GUI.
2. DPM signals FPGA via IOC, writing mode_request register.
3. Timing system synchronizes OperatingModeEvent on next clock.
4. FPGA unlocks for block-RAM write in "No-Beam" mode.
5. Java App pushes LUTs via EPICS channels.
6. ModeEvent triggers atomic enablement of new LUTs.

• Validation: DPM enforces schema consistency; expert app performs duplication and polarity field validation; non-maskable channels protected by hard-coded invariants (Carmichael et al., 31 Jan 2024).

5. Implementation Details: Resource Utilization and Protocols

Critical implementation figures for a typical MPSM board:

Resource Type	Utilization	Function
LUTs	~30%	Mode LUTs, state machine logic
BlockRAM	~40%	Config tables for 7 Machine × 4 Beam × ~200 ch
DSP slices	~20%	Analog sample scaling

Communication stack includes:

• Serializers (8B/10B, 600 Mb/s LVDS over fiber)
• Fiber interfaces: ACLK/LCLK timing, permit word transfer
• EPICS CA (Ethernet, 1 Gbps, RJ45)
• User authentication via Keycloak (OIDC)
• CRC-guarded link error handling; trip and fault logging via IOC–EPICS archiver.

6. Design Significance, Performance, and Comparative Context

This configuration establishes a tightly coupled hardware-software boundary, optimized for ultra-low-latency reaction, deterministic configuration change, and robust fault isolation in high-risk accelerator environments. Firmware logic is engineered to guarantee sub-10 μs permit propagation, with precise error tracking and configuration management safe-guarding against operator or network-induced mistakes.

Compared to more general-purpose or flexible DAQ/control systems, the PIP-II MPS stack balances:

• Deterministic Timing: FPGA-centric, synchronized via dedicated fiber timing systems.
• Robustness: Immutable invariants in configuration schemas; multi-tier inhibit logic.
• Atomicity: Control transactions only succeed in safe, non-beam states.
• Fine-Grained Validation: Per-channel fault counters, reset windows, and trip analysis facilitate high-confidence diagnostics.

These principles are central to dedicated configurations in accelerator protection, but the architectural rigor, configuration flow, and error isolation mechanisms are broadly applicable to any safety-critical control system requiring hardened real-time logic with layered configuration and recovery controls (Carmichael et al., 31 Jan 2024).