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Hi Paul,

I don't know if you know me. I'm a lead developer for the ardupilot project. You know, the project that you just accused of not being open source in an interview on http://thecrashcast.com/. I write about half the code for the project, so maybe you've heard of me.

If you've been following my work for the last 4 years on ardupilot then you would know that I'm generally a pretty mild mannered person. I try to keep my posts polite and helpful, to generally raise the tone of diydrones and open source projects in general.

Well, you better don your asbestos suit now, because I also have a rarely seen darker side. Just occasionally someone does something that pisses me off so much that I get really really annoyed. Your recent actions have done that, so here comes a flaming.

Some background

A real flaming doesn't generally come with a background introduction, but hey, I still have a mild side too (despite the fact that I am seething with anger at you right now), so why not.

I'm a long time open source developer. I started contributing to open source in the late 80s. There is a good chance that when you read this letter the bits are getting to you via computers running open source code that I've contributed to. On the wall behind me is a Free Software Foundation award for the advancement of free software. I teach a masters course on how to build and contribute to open source projects. I'm not an open source newbie. Perhaps you should have checked before making outlandish claims about ardupilot, a project that I've put my heart and sole into for so long?

I've been working on ardupilot for 3 and a half years now. In that time I've contributed over 5000 patches to the project. Given your amazing statements on the crashcast podcast and on your website about you being a defender of open source I expected to see your name in the contribution list. Strangely enough, it's not there. Did you use a pseudonym in all the contributions you have made or did you just accuse a project that you have no association with of not being open source?

How Open Source Works

As I describe in my course, open source is different for different people. Me, I'm a free software radical. I like everything I do to be FOSS (free and open source software). If I can't do something with FOSS then I see if I can write a FOSS tool to do it, then distribute it to the world. As a result I've started about 30 FOSS projects over the years and contributed to dozens more. I'm such a radical that many people in the FOSS world (including Linus Torvalds) have accused me of being too radical, and pushing the "free software or death" line too hard.

One of the big misunderstandings about open source is the insane and self-serving idea you have been pushing that the ardupilot project is somehow required, because of open source principles that you somehow fail to explain, to provide your company with binaries of our software that work on your board. That is utter and complete drivel and rubbish. You're wrapping yourself up in the open source flag while not even having the faintest idea of how open source works.

Open source project leaders can choose which hardware they support. As a lead developer of the ardupilot project I have chosen to try to make the code work on as many boards as possible. So in fact the firmware.diydrones.com site (which I maintain) does provide firmware that will probably work on your RTFHawk boards. I've also worked with people who want to port ardupilot to completely new hardware platforms. Did you notice I merged in support for Flymaple boards a few months back? Did you notice I merged in support for the VRBrain too? Did you notice the work I've been doing on porting ardupilot to the BeagleBone?

I'm guessing you didn't notice any of that or you wouldn't be making such grandiose and idiotic claims about ardupilot not being an open project.

So here's the deal. Open source project leaders get to choose what code they accept, what code they write and how the projects get managed. Really basic stuff really. I have chosen to make ardupilot widely portable and flexible, but I didn't have to. It would still be open source if I wrote the code to only work on one brand of board.

Michael Oborne is the project leader of the MissionPlanner project. He has done an awesome job building up MissionPlanner from scratch, and making it a GCS that people love to use. As the project leader for MissionPlanner he gets to set the policy. If he wants it to only load firmware to only blue boards with pink edging that have butterflies embossed on the PCB then that would be his right. I might give him some odd looks if he did that, but I'd defend his right to do it.

Because MissionPlanner is an open source project you can make it do something different if you like. If you don't like what it does then why not try something really radical like talking to him (you _did_ talk to him before accusing him of heinous crimes against the open source world? right? yes?). Hey, you could even send him a patch! Now there is a radical idea. If that fails then you could fork MissionPlanner and make it do what you want it to do. That is the fundamental succinct definition of open source after all - the right to fork. You have that right, even if perhaps you don't deserve it after all you've said in recent days.

Why do we work closely with 3DR?

If I were to believe the crap you said on that podcast then it would seem that I'm held hostage by 3DRobotics. Help, I'm an open source developer being supported by a hardware company that uses my software. Oh no!! Help me get out!!

The fact is the ardupilot developers work closely with 3DRobotics because it benefits the project. Think about that. We choose to work with them because working with them advances the aim of producing the most awesome free software autopilot that we can.

I regularly get asked by Craig Elder from 3DRobotics if there is anything he can send me to help me with my work on ardupilot. If I say "well, I fried my last Pixhawk while testing the power handling to its limits" then he pops a couple of new ones in a fedex pouch and sends it down to me in Australia. It's great!

They even pay me! I get 100% copyright on all the work I do, I get complete discretion on what code I put in and I get paid to do it. Yep, open source developers can get paid!

In fact, most large open source projects have lots of paid developers. Ever heard of the Linux kernel? Last I heard about 80% of the code is written by people who work for hardware companies that benefit from the project. This is normal. I've been paid to develop open source software by numerous companies for 20 years.

The main difference with 3DRobotics is that they are one of very few companies who have been enlightened enough to pay the ardupilot core developers. In the case of Linux there are hundreds of companies that have understood open source enough to pay the core developers. Chris Anderson from 3DRobotics saw that pitching in money to pay the people who have been working on ardupilot for so long is a good thing both for the ardupilot project and for 3DRobotics, so he did it. Now you throw that back at him and try to use it to accuse him and 3DRobotics of being some evil company perverting open source. What sort of insane logic does that stem from?

I looked in my letter box today and I didn't see any hardware from you. I bet if I talk to all the other ardupilot devs they would tell me you didn't send any hardware to them either. I haven't seen any code from you. Yet you get up on your high horse and try to claim that we owe you something? Please just crawl back into the hole you came from.

That OTP thing

The thing you have built your edifice of open source outrage on is the way that MissionPlanner checks the OTP area of Pixhawk boards and doesn't load firmware unless they match a particular public key. I have stated publicly that I don't like that behaviour. I have also made it clear that it is Michael's decision as project leader for MissionPlanner.
I have been working with other developers to try to come up with a better solution. That is how things are done in the open source world. Contributors to projects tell the project leader if they don't like something the project does and the project leader takes their ideas into consideration. Ultimately the project leader (Michael in this case) gets to choose.

So we agree?

You might think that because I also don't like the current OTP mechanism that we are in agreement. We are not. I wouldn't be flaming you in such a long winded fashion if I agreed with you.

You are taking advantage of the OTP behaviour for your own ends, and those ends have absolutely nothing to do with protecting open source.

Let's have a quick look at your actual behaviour with regards to open source and your RTFHawk project. Given your rabid defence of open source I presume you've read the license of the projects you are criticising so loudly? It's the GNU GPLv3. I happened to be on a committee that helped develop that license, so maybe you don't know it quite as well as I do. Here is a refresher. When you distribute binaries that are built from source code that is under the GPLv3 you need to (among other things) do the following:

• make the recipients of the binaries aware of their rights under the GPL. Have a look at firmware.diydrones.com for how we do that
• offer the source code to anyone who asks for it (which is why making them aware of this is so important)

So, let's see. On your website you have a binary copy of MissionPlanner modified to upload firmware to your board. Do you tell people who go there that it's GPLv3 software? Do you link to the source code? Do you offer the patches you've done? Nope, nope and nope.

What is more, you are wrapping yourself in an open source flag and trying to use that flag to sell your clone boards. You do this by criticising 3DRobtotics, a company that has done more for open source autopilots than any other company I know of. You are doing this as a company that has, as far as I am aware, done absolutely zero to benefit the ardupilot project or MissionPlanner that you are criticising.

So what now?

First off, go read up on open source. Read some of ESRs essays. Read the FSF site.

Then go away. One of the things a open source project can do is ignore people who really piss them off. You have really pissed me off. I would not accept a patch from you in future, even if you ever could be bothered to get off your ass and make a real contribution.

I will accept patches from other hardware vendors, and I look forward to working with other hardware vendors who make boards that run ardupilot, just like I have done ever since I got involved in this project. I love working with any hardware vendors who make great autopilots and who want to work with the project. I will do it regardless of whether they contribute money or hardware, because I love to see the platform grow. I won't however work with you because you have decided to start off the relationship between your company and the ardupilot project by insulting it and using those insults to further your own aims. So congratulations, you are the first company that I have banned from working with the ardupilot project, or at least working with me on it. Maybe you'd like to put that on your website?

Time to get some sleep.