Wren is a compact altimeter capable of fitting in a standard 18mm model rocket. It is designed to be assembled by JLCPCB for as low of a price as possible. The altitude, velocity and acceleration are sampled and saved at 50Hz. The battery should last for tens of hours while waiting for a launch and is charged through USB-C
A 12mm x 34mm 4 layer PCB, designed to only use components from JLCPCB's stock. Single sided assembly with only a debug connector and battery pads on the back.
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MCU: An nRF52833, small package, USB PHY and incredibly low power.
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Accelerometer: A LIS2DH rotated 45° allowing it to measure accelerations up to 22.5G instead of the typical 16G limit.
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Barometer: A BMP388 for altitude measurements, better options available but limited by availability for PCB assembly
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Flash Memory: 4Mbit of onboard flash. Should log ~4 flights at 50Hz
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Battery: LiPo charging at 30mA
The onboard firmware is being developed using Rust with the Embassy framework. The dashboard is written in Python
To flash and build run
cargo run
To run the native test build with mock drivers run
cargo run --target x86_64-unknown-linux-gnu or any arch with std