Sentinel: Component Selection
- Justin Michaud
- Mar 12
- 2 min read
STM32G474 Microcontroller
The MCU of the SDL board is an STM32G474, chosen for its extensive peripheral set and processing headroom. With multiple SPI and I²C interfaces, DMA support, and high clock speed, it can handle several sensor streams simultaneously while maintaining precise timestamping for logged data. The STM32 ecosystem and tooling also make firmware development and debugging straightforward during early prototyping.
Multiple IMUs (BMI088 + ICM-42670-P)
Two inertial sensors are included to allow validation and redundancy in flight data. The BMI088 is well known for handling high vibration environments, which makes it a strong candidate for rocket applications. The ICM-42670-P serves as a secondary IMU and provides additional data for comparison, filtering experiments, and potential sensor fusion work.
High-G Accelerometer (H3LIS200DLTR)
Rockets can exceed the measurement range of typical IMU accelerometers during motor burn. The H3LIS200DLTR provides a very high-range acceleration measurement so the system can capture the transition between normal IMU ranges and extreme launch accelerations without saturating the sensors.
Dual Barometers (LPS22HH + MS5611-01BA)
Altitude is measured using two different pressure sensors. The LPS22HH provides a modern, compact barometer with good resolution and low power consumption, while the MS5611-01BA is included as a secondary high altitude reference sensor. Having two devices allows performance comparisons and improves confidence in altitude data during early flight testing.
Magnetometer (MMC5983MA)
A MMC5983MA magnetometer is included to provide heading and orientation reference data. While not strictly required for basic rocket flight logging, it enables experimentation with orientation estimation and more advanced sensor fusion algorithms in future firmware revisions.
High-Speed Non-Volatile Memory (W25Q128JV QSPI Flash)
The board includes W25Q128JV QSPI flash as a high-speed non-volatile storage device. Unlike a micro-SD card, which can momentarily disconnect or stall during high vibration, the onboard flash provides a reliable buffer for high-rate logging. Data can be written quickly to flash during flight and later transferred to the SD card after landing.
Micro-SD Storage
A micro-SD card provides the primary removable storage for flight data. This allows quick data retrieval after recovery and offers effectively unlimited logging capacity relative to the duration of typical test flights.
Communication Architecture
Sensors are connected using a combination of SPI and I²C buses, selected based on bandwidth requirements. Higher-data sensors such as IMUs use SPI for reliable high-speed transfers, while lower-bandwidth sensors like barometers and the magnetometer operate over I²C.
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