Impulse 1.0
Baseline Architecture
Teensy 4.1 with MPU6050/BMP280 and initial pyro circuitry; pyro path was non-functional.
Sisyphus — Subsystem
Flight Computer
Impulse 2.5 is the current custom Sisyphus avionics board for flight sensing, actuator control, pyro events, and telemetry. This layout groups hardware photos, CAD, and specifications into one place for faster understanding.
PCB Specs
- Microcontroller: Teensy 4.1
- Sensors: ICM-42688 IMU, DPS-310 barometer, and ATGM336H GPS on a separate damper-mounted sensor board, fused in software by a Kalman-based state estimator
- Pyro outputs: 4 channels at 7.4V, each with a continuity-check LED circuit
- Control outputs: 7 servo outputs
- Status and alerts: onboard buzzer and RGB LED
- Power system: one 80C 7.4V lipo battery
PCB History
Development & Iterations
The flight computer went through several major hardware revisions. Each iteration solved problems revealed by the last, from basic pyro failures to full SMD layout and trace-width discovery.
Impulse 1.1-1.3
Output Expansion
Expanded servo outputs and switched to larger MOSFETs, but pyro reliability remained unresolved.
Impulse 1.4
Power Isolation
Added dedicated LiPo circuit for pyros to isolate high-current firing from core avionics.
Impulse 2.0
SMD Jump
Attempted ESP32-S2 full-SMD board and adopted BNO055 plus DPS310 sensor stack for future revisions. I had no idea what I was doing in hindsight.
Impulse 2.1
Teensy Return
Mostly-SMD layout with Teensy 4.1, continuity checks, and dedicated sensor power; pyro troubleshooting intensified.
Test Boards
Pyro Troubleshooting
Isolated pyro and regulator boards exposed trace-width as the pyro ignition bottleneck.
Impulse 2.2
Pyro Success
Widened pyro traces enabled reliable firing and powered the first successful Sisyphus launch.
Impulse 2.3
Density Upgrade
Swapped to smaller SMD MOSFETs while preserving wide pyro routing for robust ignition.
Impulse 2.4
Better everything
New pyros with MOLEX connections, fully SMD power regulation, seperate sensor board JST connection plus redundant onboard sensors, battery charge and sensor detect LEDs, and 5 additional servo outputs.
Sensor Board
Dedicated Sensor Board
Separate module with an ICM-42688 IMU, DPS-310 barometer, and ATGM336H GPS, mounted on vibration dampers and fused in software by a Kalman-based state estimator.
Impulse 2.5
Power and Switch Cleanup
Switched from two small lipos to one big lipo battery with higher discharge rate for pyros. Bulked pyro FETs to give significant practical margin. Added multi-layer planes for more robust pyro circuit.