Sentinel Data Logger

The first SDL flights were not about proving a finished avionics system. They were about getting real data from a rocket, validating the basic hardware and firmware, and finding out what needed to improve next. At this stage, SDL was still closer to a debug data logger than a polished flight computer. That was intentional. The goal was to get the board into a real flight environment, collect enough useful data to understand what happened, and use that data to guide the next v

SDL is built around a simple idea: collect useful flight data, store it reliably, and make it easy to analyze after the flight. That sounds straightforward, but the data has to move through several different paths. During development, USB serial output is useful because it gives immediate feedback. During flight, onboard flash is the priority because it can store data directly on the board. After flight, SD card export makes the data easy to retrieve. LoRa telemetry adds a li

SDL started as a rocket data logger, but even a basic flight data logger quickly becomes more complicated than just reading a sensor and printing values. The board has multiple IMUs, barometers, GPS, magnetometer, power monitoring, onboard flash, SD card storage, USB output, LoRa telemetry, status LEDs, and a buzzer. Each device has its own setup process, communication bus, timing requirements, and failure modes. If all of that code lived directly in the main loop, the firmwa

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. ICM-42670-P BMI088 Multiple IMUs (BMI088 + ICM

The Sentinel Data Logger (SDL) began as a compact avionics platform designed to capture high-resolution flight data during experimental rocket launches. Early in development, the focus was on building a robust hardware foundation capable of recording multiple synchronized sensor streams while remaining reliable in the harsh conditions of rocket flight. The board integrates an STM32-based microcontroller with several onboard sensors—including inertial measurement units and bar