KWIIs

The KWIIs (Knows Where It Is) flight computer was TBNL’s first attempt at a custom flight computer - designed from the ground up, the KWIIs flight computer gave us invaluable knowledge and experience, which will be carried forward in all future projects.

KWIIs was designed with modularity and airframe space constraints in mind, and had been split across 3 interconnected PCBs: the Navigation (NAV), Telemetry (TLM), and Power (PWR) subsystems. This modular approach comes with a host of benefits ranging from improved development turnaround times to enhanced salvageability in the unfortunate case of a recovery failure.

Features

• modular, 3-board design

• dedicated NAV and TLM computers

  • Teensy 4.x platform

  • inter-computer communication over I2C or SPI

• ~900MHz LoRa radio for communication with ground equipment

• exposed I2C and SPI busses for expansion

• piezo buzzer and RGB LED for state indication at a glance

• primary IMU: BNO055

  • ±16g

• backup / high-G accelerometer: ADXL375

  • ±200g

• altimeter: BMP390

  • ±3 Pascals / ±0.25 meters

• GPS + GLONASS connectivity with optional external antenna

• in-flight soldered flash storage which is copied to a removable microSD card after landing

• 6 independent pyro / high-voltage channels

  • pass along 3S/4S LiPO battery current through the KWIIs PWR board at up to 12A (instantaneous) or 1A (continuous) per channel

  • detect continuity per channel through a 1M-100K voltage divider

• accept (externally) regulated battery voltage or an externally supplied 5V source (typically through a quick-disconnect panel on a launch tower umbilical arm) and preferentially draw current from the external source when available to preserve battery power

• support for 2-axis TVC servos

• support for a reaction wheel - either directly or through an ESC for larger wheels / motors