ProjectInertia

This is an open-source project to build a low-cost Commercial-Off-The-Shelf on-board computer for small CubeSat missions providing extremely low power usage and tolerance to radiation effects. At this point in time it is mostly a playground to test out new technologies and learn from it. The first hardware prototype iteration 1 is currently in production.

Table of Contents

• Commercial-Off-The-Shelf in Space
• Hardware Development
  • Features
  • Manufacturing
• Firmware Development
  • Peripheral Access Crate
  • Toolchain

Commercial-Off-The-Shelf in Space

The usage of Commercial-Off-The-Shelf (COTS) components in Space has been a topic of research for many years already due to the benefits of higher performance and lower costs, when compared to their radiation hardened counterparts.

However, COTS components are subject to a manifold of radiation induced failure modes, that need to be considered during system design [Sandia2018]. Destructive Latch-Up events are automatically detected and mitigated by an on-board circuit breaker. After a hold-down time of some dozen µs, the board is reconnected to the power source. This project proposes the use of a COTS microcontroller that is based on Ferro-Electric RAM. The Ferro-Electric RAM cell itself is resilient against various Single Event Effects [Fetahovic2017]. However, the peripherals within the respective integrated circuit might still experience Single Event Effects [Bosser2018]. These will be recovered by the internal watchdog circuit, present in the microcontroller hardware.

Developing hard- and software products for Space application do require a lot of careful design choices. Thus, this project aims for the most simple and very low cost design to minimize potential sources for failures.

Hardware Development

The design is centered around the series of Ferroelectric-RAM based Microcontroller Units from Texas Instruments. The first prototype is using the MSP430FR6972IPMR.

Features

The current hardware design (iteration 1) features the following:

• Microcontroller based on FRAM technology clocked at 16 MHz
  • 64 kB On-Chip Memory for Code and Data
  • Internal Hardware Watchdog to recover from Functional Interrupts
  • Availability of Ultra Low-Power Modes
• External 16 kB Non-Volatile FRAM Memory
• Automatic Latch-Up Detection
  • Circuit Breaker limits at 1500 mA
  • Current Monitoring
• 12V Power Input
  • Optional 5V Input for Development
• Input/Output
  • 2 x UART
  • 1 x I²C
  • JTAG Programming Interface
  • 3.3V output for peripherals
  • Screw Terminals for all Interfaces
• CubeSat Size
  • 1/4 U or (5cm x 5cm)

Manufacturing

You can find the schematics, gerber files and bill of materials in the hardware folder.

Firmware Development

The firmware is being developed using Embedded Rust to explore the versatility of this language in a environment with extremely limited resources and the need for high reliability. Useful resources may be obtained from the awesome embedded Rust list.

Peripheral Access Crate

The PAC has been successfully created for the MSP430FR6972 chip used in prototype iteration 1.

• msp430fr6972 (beta)

Toolchain

The current toolchain uses:

• Rust Edition 2018 (nightly)
• msp430-gcc-elf compiler
• msp430-bsl-python programmer