PNav Objectives

These requirements are definitly IN PROGRESS. Have any suggestions? Send them to me at paul(at) 

PNav Autopilot requirements: 

Primary Objective: To create a  Parallax Propeller Autopilot for a fixed wing R/C aircraft using GPS as the primary form of guidance anywhere on earth.

Secondary Objectives:

Realtime Heads Up Display technology for first person flight 


High Level Requirements:

  • GPS Navigation. Routines to store and calculate navigation parameters throughout a flight.   Additional input are permissible (ie thermopile, pitot tube, barometric pressure, etc)  but system must stand on its own for navigation.
  • Radio Control Inputs and Outputs for command and control of servos
  • SD Card Access
  • Waypoint storage
  • Data Logging with integrated Google Earth compatibility
  • Video Downlink from onboard camera
  • On Screen Display / HUD with relevant flight information.

Project Components Definition:

  • GPS - Input of standard NMEA strings is complete with Perry's GPS_IO  SPIN code. I am using a US Globalsat 408 Sirf III chip.
  • SD Card access is standard with Tomas Rokicki's Fat16 code.


  • Processor: Parallax Propeller 8 core multiprocessor prototype board $25.
  • Memory - FAT 16 compatible SD cards $5
  • US GlobalSat GPS SIRF-III receiver $60
  • 6 channels of R/C input/ 6 channels servo output. $~150
  • SD Card for dataloging and Google Earth integration $10
  • 2 video camera inputs and a switching mechanism $~100
  • On-Screen Display, Fully controlled by the main system
  • Video transmitter connection and RCA test jacks$150
  • USB programmer jack and flash memory $25
  • 4 mounted LEDs with one external IR LED jack $1
  • 2 momentary switches  $5
    • Part links to come...

General parts supplier: