Nerd Fever

Here is a quick index to my posts about my GPS-guided model rocket recovery project.

The key idea is to have the the rocket fly itself back to the launch pad using a steerable parachute and onboard GPS.

At this point I have the “Rev 3″ PCB hardware and software (based on a PIC18) working well.  It doesn’t yet fly back to the launch pad, but it does do a lot of useful things, and has made many successful flights:

• Altimeter (good to about 2 feet precision)
  • Electronic ejection at apogee
  • Launch detection
  • Altitude logging
  • Beeps out maximum altitude reached
• Drives a digital camera for in-flight photos
  • Direct shutter trigger
  • Infrared signal generation
• Complete flight log:
  • Lat, Lon, Speed, Altitude, Status
• Ejection detection via IR phototransistor
• 3 push-buttons, 3 LEDs
• Piezo speaker output
• “Loud horn” (smoke detector horn)
• Drives a hobby servo (to steer the parachute…someday)

I’ve put all the source code, schematics, and PCB layouts (in Eagle PCB) for the “Rev 3″ design online in the following posts:

• Project Intro – Interim Report: GPS-guided Rocket Recovery
  • (or, Nevada Dave and the Rocket-Eating Trees)
• “Rev 3″ design part 1 – Hardware description & schematics
• “Rev 3″ design part 2 – Software introduction (source code is here)
• “Rev 3″ design part 3 – Source code overview
• “Rev 3″ design part 4 – main.c
• “Rev 3″ design part 5 – stateMachine.c
• “Rev 3″ design part 6 – isr.c (interrupt service routine)

If anything is unclear, let me know – I’ll try to fix it.

The project isn’t finished – as of this writing (January 2010) I’m just starting to populate the “Rev 4″ printed circuit board, which will use a PIC32 MCU and SMD components.  I’m pretty confident I’ll get this version flying back to the launch pad (it works very nicely in the MATLAB simulation).  Watch this space.