Flight computer PCBs have arrived

The high powered rocket designed to go supersonic has been under development for some time now at the Imperial College Space Society. Recently, we have been designing and building the flight computer. We have settled on a single stage minimum diameter rocket(either 38mm or 54mm diameter rocket that will take it past mach one. Simulations show that it will reach mach 1.4.

The following requirements were set before designing:

Rocket flight computer requirements:

  • flexible for two stage or one stage rocket
  • must have buzzer
  • must have flashing LEDs to help with recovery on the ground
  • must have usb programmer and possibly for accessing stored data
  • 3 mosfets for rocket trigger, parachute triggering, spare
  • rocket to ground telemetry link
  • GPS for tracking and recovery
  • runs at 3.3V logic levels(CMOS)
  • 9 dof acclermoeter, gyroscope, compass. Max accleration would be 100g
  • pressure(and temperature) sensor to measure altitude
  • current sensing to see the amount of current going into fuses
  • MOSFET must be able to supply 1.2 amps for at least 10milliseconds. Bridge wire resistance is 1.2-1.8 Ohms
  • Must be able to run for at least 1 hour continueously
  • must be hand solderable. Perferably
  • 100Hz sample rate from sensors(except GPS)
  • must record data continueously for at least 3min
  • 14 parameters to record: 4 characters:{accl_x, accl_y, accl_z, gyro_x, gyro_y, gyro_z, compass_x, compass_y, compass_z} + 6 characters:{pressure}+ 3 characters:{temperature}+ 7 characters{Longitude, latitude}+4 characters:{altitude} Assuming ascii encoding, 504 bits per string for raw data. Including commas and carriage return, each reading is ~600 bits.
  • Total data storage required: 600bits * 60s * 100hz * 3min = 10.8 Mbits

With these requirements in mind, we settled on the following components that have to go on the flight computer

Major components of V1.1 flight computer

  • ST Microelectronics H3LIS100DL: 100g 3-axis accelerometer
  • ST Microelectronics LSM9DS1: 9 degree-of-freedom Accelerometer, Gyroscope and Magnetometer in 3 axis
  • TE Connectivity MS5607: Temperature and pressure sensor
  • Sillicon Labs SI4463: 433 Mhz ISM band Telemetry radio transceiver
  • Ublox MAX M8Q: GPS module
  • Atmel SAMD21J18: Microcontroller 64 pin TQFP package
  • Vishay Si7232DN: Dual N-Channel 20 V (D-S) MOSFET for 2 channel pyros
  • Molex 2066400001: GNSS Active Patch Antenna with Low-Noise Amplifier

The PCB was designed with KICAD and sent off to a manufacturer to be produced. Sincere thanks to Richard Ibbotson from the Imperial College Advanced Hackspace for his invaluable advice throughout the design process. As of now, 18/10/19, the PCBs and Stencils have arrived and the next thing we need to do is to assemble, program and test the flight computer. The schematic for the circuit is here. All our hardware and code is documented on Github.

PCBs and Stencils have arrived.
Reflow oven at the Imperial College Advanced Hackspace