Avionics

System Overview

The avionics system is responsible for the research, design, and implementation of a remote tracking system for the rocket. The avionics telemetry unit (ATU) is mounted in the nose cone of the rocket; the nose cone is made out of fiberglass which is RF (radio frequency) transparent. The ATU wirelessly sends data to a ground station, which receives and displays the data through a graphical user interface (GUI). This is all capable by using a pair of XBee-PRO XSC transcievers, which are driven by Teensy 3.6 microcontrollers.

Parts

Teensy 3.6 microcontrollers
Digi XBee-PRO® XSC transceivers
UBLOX MAX M8Q GNSS modules
ADXL377 accelerometer
MPL3115A2 pressure/altimeter/temperature sensor

Avionics Top-Level Block Diagram

Hardware Schematics

Avionics Schematics.pdf

Firmware

The avionics firmware code is uploaded under a GitHub repository. The master branch contains the most recent iteration of. Code development for specific launches exist on their own branches.

Data Packet Format

Each packet sent by the ATU and received by the ground station is formatted like so:

ECEUSLI-at-Oregon-State/Avionics_FirmwareContribute to ECEUSLI-at-Oregon-State/Avionics_Firmware development by creating an account on GitHub.

For error checking, the ATU will calculate a checksum value by summing the ASCII values from the characters of the previous fields. Once calculated, the checksum is appended to the packet and sent along to the ground station. The ground station, knowing the data format, will extract all the fields excluding the checksum, recalculate the checksum value, and compare this newly value with the original. If the two match, it indicates that the packet was successfully received.

Redundancy

Flight data transmission is crucial to the mission. To ensure information is not lost, the avionics system features three points of data logging: the ATU microcontroller, the ground station microcontroller, and the ground station PC. The Teensy 3.6 features a microSD card slot through which logs can be saved. For the PC, the logging is conducted through the GUI and saved locally.

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