[Update October 2011: This post is no longer the latest version version of the board; see here.]

Almost a year ago I posted the schematics and software for the “Rev3” version of my rocket flight computer/altimeter.

I’ve now got the code ported over and working well on the “Rev4” hardware. This is far more integrated – the parachute deployment circuits, piezo speaker, and GPS are all on the PCB now, and it’s based on the much more powerful PIC32 MCU. So (per a couple of requests), I’m posting the software and schematics for that today.

Rev4.1 Schematic (click for full size)
At this point I do have navigation software that (in theory anyway) steers the rocket’s parachute to return back to the launch pad. It seemed to work the one time I’ve had a chance to try it (November 6 – you can read the details in my flight test notes here). It still needs a good deal of tweaking before it’ll be working as well as I want it to – that’s a project for next year’s flying season. One day I’ll get around to posting a full update on the project here.

The code I’m posting today, like the earlier “Rev3” code, does not include the navigation code. But it does include everything else – logging altimeter, parachute deployment, GPS, servo control, etc. Because of the “abuse potential” of the nav code (think of navigating things to places where they ought not to be), I don’t intend to make the nav source code public. Once it’s working well, I might be interested in working with reputable vendors to sell hardware that includes this function, but if I do, it’ll have some protections in place against abuse. The main protection I’m considering is to limit the target location the system will aim for – it has to be a place the unit has physically been since it was powered up (you won’t be able to program in some other location). That way, if you’re not allowed to go somewhere with a handful of blinking rocket electronics, you can’t land the rocket there either. I’d like feedback on this idea. (Yes, anything can be hacked if you put enough effort into it, but my goal is to make it harder to hack the system than for “bad guys” to build their own – there are, after all, books on the subject…)

Anyway, here are the links to the hardware design (schematics only) and software. The deal on rights is exactly the same as with the “Rev3” postings:

Hardware rights: I hereby grant everyone and everything in the universe permission to use and modify this hardware design for any purpose whatsoever. In exchange, you agree not to sue me about it. I make no promises. By using the design you agree that if you’re unhappy the most I owe you is what you paid me (zip). That seems fair.

Here is the schematic for the hardware, in both PDF and as the original CadSoft EAGLE file (see also the ReadMe.txt in there): Rev4.1Schematic.zip

And for the software:

Software rights: I hereby grant everyone and everything in the universe permission to use and modify this software for any NON-COMMERCIAL purpose whatsoever, PROVIDED that you (a) agree not to sue me about it, (b) credit Nerdfever.com as the original source of the software in any publications, and (c) agree that I make no promises and that if you’re unhappy the most I owe you is what you paid me (zip, zero, nada, nothing). Oh, and you agree to USE THIS AT YOUR OWN RISK, that you’re a responsible adult and know that rockets can be dangerous and hurt people if you’re not careful (regardless of whether or not software is involved) so you’ll be careful and will not blame anyone else if you screw up (especially me).

I’ll be very pleased if you leave a comment or drop me an email if you find it useful, but you don’t have to.

For COMMERCIAL use, ask my permission first. If you’re going to make lots of money off my work, I’d like a (oh-so small and reasonable) cut. But I’ve no intention of giving anybody heartache over small amounts – just ask, I think you’ll find me surprisingly easy to deal with.

Here is the the Rev4 code for PIC32, including the Microchip MPLAB IDE project files, just as it appears in the project folder: Rev4.1Code.zip

Although it’s improved in lots of minor ways, the structure of the code is very similar to the Rev3 code, so please use the 6-part posting from last year as a guide to the software. The main UI change from then is that arming/disarming is now done via a reed switch. This lets me arm and disarm the system on the launch pad using a magnet, so I don’t have to make holes in the rocket body for a switch (and worry about lining up the switch with the hole). (Search for “MAGNET” in the code).

Feedback and suggestions for improvement are very welcome. I’m very happy to help out anyone who wants to work with this stuff – just drop me an email or post a comment here.