Identity-II Electronics

Electrical hardware of data acquisition and control system of Identity-II rocket

Specification

1. Data Acquisition
   • Altitude measurement via BMP280
   • 3-Axis Accelerometer, 3-Axis Gyroscope, 3-Axis Magnetometer reads data in every cycle
   • System time is recorded with the data
   • All the data measurements are taken in every 5-7 ms
   • Raspberry Pi camera module saves the recorded image automatically after the power is on
2. Communication
   • Zigbee communication is tested to reach 1000m without severe interference
   • Baud rate of 38400 is used for serial communication with the XBee module; At higher rate, some Arduino chips are not able to handle the speed of the signal alternation
   • Rocket status code along with the current altitude and time is sent via Zigbee channel
3. Control
   • Drogue parachute ejection at the peak altitude; Simple peak detection
   • Main parachute ejection in two modes
     1. Relative altitude mode (Max. Alt. < 390m): Main parachute ejection at "alt. = max. alt. - 70m"
     2. Absolute altitude mode (Max. Alt. > 390m): Main parachute ejection at "alt. = 320m"
4. Others
   • Additional 6 analog pins of Arduino Micro core can be reachable at the back of the core module

Additional Requirements

Hardware

• Li-Po battery 3.7V, minimum 2000 mAh (x3)
• Buck converter 5V output, minimum 2A (x1)
• Arduino Micro (x1)
• Digi XBee-Pro (x1)
• MicroSD card adapter (x1) (You may use other boards)
• GY-91 IMU sensor (x1)
• L293B (x1)
• Raspberry Pi 3 or high (x1)
• PiCamera for RPi (x1)
• Power switch (x1)
• Some terminal blocks
• Some hexagonal supporters, 3-phi

Software

• Arduino source code ()
• Data decoder code ()

Installation

There are three PCB layers with additional battery mount assembled in the following order:
(top)
battery
power module
core module
imu module
RPi Camera and Power button mount
RPi

Credit

Jaerin Lee
Lead Electronics and Software Developer
SNU Rocket Team Hanaro

Documented with KiCAD version 5.0.0