Hardware Microcontroller

Overview

The microcontroller coordinates the collection of GPS location data, accelerometer data, and transmitting tracking data back to ground units. The microcontroller collects GPS position every second, accelerometer data every 2 seconds, transmits GPS position every 15 seconds.

Hardware

Microcontroller:

The microcontroller is a Rabbit LP3500 FOX. It is plugged into a custom-made carrier board to allow for easier interfacing. It is a low-power board, drawing <20mA at 7.4 MHz. Specifications can be found at
http://www.rabbitsemiconductor.com/products/lp3500/

GPS:

The GPS is a Garmin GPS 35 TracPak. It can operate off of 6-40VDC and draws about 80mA at 12VDC. It has the capability to operate at the 100,000 ft range where our target altitude is. Specifications and documentation can be found at:
http://www8.garmin.com/products/gps35/spec.html

Accelerometers

Two accelerometers are used in conjunction with the microcontroller to produce a 3-dimensional acceleration map, a two-axis and a one-axis. The one-axis accelerometer is the ADXL103 and the two-axis is the ADXL203. They are oriented such that all 3 axes are perpendicular to determine how the payload is accelerating in space. Specifications can be found here:
2 axis — http://www.analog.com/en/prod/0,2877,ADXL203,00.html
1 axis — http://www.analog.com/en/prod/0,2877,ADXL103,00.html

Transmitter:

The transmitter is a small, handheld 2-way using the TigerTrak TM-1+ for a modem. Specifications for the TM-1+ can be found here:
http://www.tigertronics.com/tm1.htm

Notes:

All peripherals are connected to the microcontroller through serial ports.

—-Blair Carter 05/09/07