A Modular PolarFire SoC FPGA-Based Command & Data Handling Solution for Rockets

Temperature Measurement

Temperature measurements are implemented using a dedicated high-resolution sigma-delta acquisition subsystem based on an AD7124-class converter.

The proposed architecture supports:

• 4–5 temperature channels
• Thermocouples
• Cold Junction Compensation (CJC)
• NTC/PTC sensors
• 10 kΩ resistive sensors

Because temperature varies significantly more slowly than pressure, these measurements are intentionally separated from the high-speed control loop and acquired at a configurable scan rate between 1 and 10 Hz, reducing computational load while maintaining excellent measurement accuracy.

Open item for confirmation: the Hardware Requirements Document (HRD) specifies five temperature channels, whereas earlier project documentation referenced four. Final channel count should be confirmed before schematic completion.

Solenoid and Auxiliary Outputs

The power output section provides the digital actuation required for propulsion and vehicle systems.

The current concept includes:

• 8 smart high-side solenoid drivers
• Rated at 24 V / 4 A
• Integrated protection and diagnostics

In addition, the board incorporates:

• 6 protected auxiliary high-side outputs

These outputs collectively satisfy the HRD requirement for 18 Power MOSFET GPIO channels, allocated as:

• 8 solenoid outputs
• 4 TVC outputs
• 6 auxiliary outputs

Confirmation requested: this interpretation assumes that the 18 MOSFET GPIOs represent the total available output population, rather than 18 additional channels beyond the listed functions.

TVC Power Conditioning

Thrust Vector Control actuators present demanding transient power requirements during motor startup.

To address these requirements, each actuator channel incorporates dedicated in-rush management consisting of:

• Individual hot-swap controller
• Local pre-charge circuitry
• Dedicated hold-up capacitor bank
• Supply from the 36 V power rail

Each channel is designed to tolerate approximately:

• 45 A in-rush current
• 100 μs duration

This localized architecture minimizes supply disturbances and prevents simultaneous actuator startup from causing voltage collapse on the vehicle power bus.

Power Architecture

The add-on board accepts both:

• 24 V input
• 36 V input

Each supply incorporates:

• Input filtering
• Transient Voltage Suppression (TVS)
• Protection circuitry

The 24 V rail powers the solenoid and auxiliary outputs, while the 36 V rail is dedicated to the higher transient demands of the TVC actuators.

Separating these domains improves system robustness and reduces conducted electrical noise between propulsion control and sensitive analog acquisition circuitry.

Interfaces

No additional communication interfaces are required on the peripheral board.

All external communications are provided by the standard OBC through its comprehensive complement of serial, CAN, Ethernet, USB, and GPIO interfaces. The peripheral board therefore functions as an intelligent I/O expansion module, with all sensor acquisition and actuator control synchronized by the PolarFire SoC FPGA.

Outstanding Design Items

While the concept has been validated, several system-level parameters require confirmation before progressing to detailed schematic capture and PCB layout.

1. Analog Signal Domain and Filtering

For each of the 60+ analog input signals, the following design assumptions require confirmation:

• Ground reference strategy
• Whether sensor loops are vehicle-referenced or galvanically isolated
• Required anti-alias and bandwidth filtering for each sensor type
• Continuous and stall current requirements for the TVC actuators (in addition to the specified 45 A / 100 μs in-rush characteristic)

These parameters directly influence front-end protection, filter design, grounding architecture, and overall EMC performance.

2. Control Loop Timing

The current assumption is that the primary flight control loop executes at:

• 600 Hz
• Approximately 1.67 ms per control cycle

Under this timing:

• Pressure acquisition comfortably supports the required sampling rate.
• Temperature is treated as a slow-varying parameter and scanned independently at 1–10 Hz.

Confirmation requested: temperature measurements are assumed not to participate directly in the 600 Hz closed-loop guidance and control algorithm.

 The OBC-HYPER-Polar architecture demonstrates a scalable and highly integrated avionics solution for modern launch vehicles. By combining the deterministic processing capabilities of the Microchip PolarFire SoC FPGA with a compact, mission-specific peripheral board, the platform delivers a complete Command & Data Handling system capable of acquiring more than 60 sensor inputs while simultaneously driving propulsion valves, auxiliary loads, and thrust vector control actuators.

With the concept design now validated on a single 100 × 140 mm expansion board, the remaining activities are focused on confirming system-level electrical assumptions and finalizing interface requirements before schematic completion and hardware implementation. The resulting platform offers a flexible, reusable avionics architecture suitable for a broad range of rocket missions, from technology demonstrators to operational launch vehicles.