Choosing the Best Space-grade Microcontroller in the ARM Cortex Series

When it comes to choosing the right microcontroller for space applications, the requirements are often much stricter than those for terrestrial environments. Space-grade microcontrollers, designed to endure the harsh conditions of space, particularly the high levels of radiation, require careful selection and significant investment. The ARM Cortex series is popular due to its robust design and flexibility, making it a prime candidate for space-grade applications. This article explores the factors to consider when selecting space-grade microcontrollers, with a focus on the ARM Cortex series.

The Importance of Radiation-hardened Microcontrollers in Space

In space, the environment is not only harsh but also unpredictable. The vast exposure to high levels of radiation, especially ionizing radiation, can cause significant damage to conventional electronic components. For critical space applications, such as satellites and spacecraft, it is essential to use radiation-hardened microcontrollers (rad-hard microcontrollers) to ensure long-term reliability and functionality.

ARM Cortex and Its Suitability for Space Applications

The ARM Cortex series, developed by ARM Holdings, is known for its high performance, low power consumption, and wide range of applications. The ARM Cortex series covers various architectures including Cortex-M, Cortex-R, and Cortex-A, each designed for specific performance and power requirements. Due to its flexibility and emphasis on energy efficiency, the ARM Cortex series is well-suited for space-grade microcontroller applications. However, the key challenge lies in ensuring that these microcontrollers can withstand the harsh space environment.

Key Considerations for Space-grade ARM Cortex Microcontrollers

1. Radiation Tolerance and Radiation-hardened Components

When selecting a space-grade ARM Cortex microcontroller, the primary factor to consider is its radiation tolerance. Radiation-hardened microcontrollers (rad-hard) can withstand high levels of ionizing radiation, such as cosmic rays and charged particles from the sun. These microcontrollers are typically manufactured using special processes and materials that enhance their resistance to radiation-induced damage. Indium phosphide (InP) and gallium arsenide (GaAs) are common semiconductor materials used in manufacturing rad-hard microcontrollers due to their superior radiation resistance.

2. Aerospace Industry Certifications and Standards

Space-grade microcontrollers must meet stringent standards set by the aerospace industry. This includes certification from organizations like ESA (European Space Agency), NASA (National Aeronautics and Space Administration), and the IEC (International Electrotechnical Commission). Certification ensures that the microcontroller meets specific quality, performance, and reliability criteria. Some of the key certifications include ESA-SSC, NASA-STD-8739C, and IEC-61508. Selecting a microcontroller that has obtained these certifications is critical for any space application.

3. Temperature Range and Operating Conditions

Space applications often involve extreme temperature conditions, from the intense heat of the Sun's proximity to the extreme cold of deep space. A microcontroller must operate reliably over a wide temperature range, from -55°C to 125°C or even beyond. The ARM Cortex microcontrollers are designed with robust temperature tolerance in mind, but space-specific versions may require additional cooling or heating mechanisms to ensure reliable operation in such harsh conditions.

4. Radiation Testing and Validation

Before a microcontroller can be used in space applications, it must undergo rigorous radiation testing. This includes various types of radiation testing, such as total ionizing dose (TID), single event effects (SEE), and single event upsets (SEU). Testing ensures that the microcontroller can withstand the expected radiation exposure and maintain its functionality. Virtual radiation testing, where the effects of radiation on the microcontroller are simulated, can also be used to validate the microcontroller's performance before physical testing.

5. Radiation Hardening Through Design Techniques

Another approach to improving radiation tolerance is through design techniques such as Triple Modular Redundancy (TMR), Error Detection and Correction (EDAC), and other fault-tolerant design methods. These techniques can help mitigate the impact of radiation-induced errors and ensure the microcontroller's reliability in a radiation-rich environment.

Popular ARM Cortex-based Space-grade Microcontrollers

Several ARM Cortex-based microcontrollers are well-suited for space applications, including:

1. ARM Cortex-M4F

ARM Cortex-M4F is a highly flexible and power-efficient microcontroller that includes on-chip floating-point unit (FPU). It is widely used in space applications due to its low power consumption and high performance. However, to make it suitable for space applications, additional radiation-hardened components and design techniques are required.

2. ARM Cortex-R5F

ARM Cortex-R5F is designed for real-time applications and offers high performance with low power consumption. It is particularly suitable for tasks that require strict timing and reliability, such as spacecraft and satellite control systems. Special care must be taken to ensure that the manufacturing process and design techniques used in the production of this microcontroller meet the required radiation-hardened standards.

3. ARM Cortex-A72

ARM Cortex-A72 is a high-performance microcontroller designed for complex and computationally intensive tasks. While it is not designed for space-specific applications, its high performance makes it a candidate for space applications where computational power is critical. Radiation-hardened versions of this microcontroller, with appropriate modifications and testing, could be used in space applications.

Conclusion

Selecting the best space-grade microcontroller from the ARM Cortex series involves a comprehensive evaluation of several factors, including radiation tolerance, industry standards, temperature range, and radiation testing. By considering these critical aspects, space engineers and designers can choose the most suitable microcontroller for their applications, ensuring reliable operation and sustained functionality in the challenging environment of space.