Rocketry Software

Software used to log data on a university student rocketry club.

No charges were fired off this, it was simply to record data.

Saves telemetry to on-board microSD card as .csv.

Modules used

• Teensy 4.1
• High G Accelerometer: H3LIS331
• Low G Accelerometer: MPU 9250
  • Gyroscope, Magnetometer, Temperature Sensor.
• Barometer: LPS22
  • Ambient temperature sensor

Communication with all modules is done over I2C.

When powering on, make sure that the MPU (Low G Accelerometer, Blue Board) has +z facing up to ensure good calibration.

Software Dependencies

As can be expected for a project using many different modules, some software dependencies are required before you can compile the system. Here is the list. They will need to be installed through Arduino's IDE

• Serial Communication Bus
  • Wire.h
• High G Accelerometer uses the Adafruit H3LIS331DL Module, and requires additional libraries to function. This module is pending a replacement currently.
  • Adafruit LIS331
  • Adafruit Unified Sensor
  • Adafruit BusIO
• Barometer also has similar dependencies. The Unified sensor and BusIO libraries only need to be installed once.
  • Adafruit LPS2x
  • Adafruit Unified Sensor
  • Adafruit BusIO
• The MPU uses a custom library written by Wolfgang Ewald. It is by far the best in terms of signal to noise ratio and accuracy with the low g accelerometer
  • MPU9250_WE
• The Teensy also has a CPU Temperature sensor. This library is custom and can be found here
  • https://github.com/LAtimes2/InternalTemperature
• The Teensy also has an SD Card slot. This can be accessed using Arduino's built in SD library.
  • SD.begin(BUILTIN_SDCARD);

Error Handling and Debugging

The Teensy 4.1 board has a built in amber flashing light. This is separate from the read/write red light. It will blink during normal operation.

If at any time during startup/initialisation that it cannot connect to a module, it will halt the boot sequence and blink the following codes:

• Short Short Long
  • Accelerometer Error (Either one)
• Short Long Long
  • Barometric Error
• Short Long Short
  • SD Card Error
• Constant Blinking
  • Initialisation done, in running normally

If it does error, power cycle after making a fix.

If a module is disconnected during normal operation, the system will continue logging frozen data or NAN values. It should not outright crash (SD Card will cause a brief system hitch).