I'm currently making an android application that reads data from an hydrometer that sends it via Bluetooth serial. But when I connect to it, it doesn't send anything, probably expecting control commands to be inputted.
Is it legal to use those commands or should I ask for them to the vendor?
In case of that being legal, my idea is to connect an already functioning android app for the device to my laptop and listen for those commands. Is that common practice? Is it possible for that to be successful?
In case of that being illegal and I should contact the vendor, how common is it for them to give them for free or sell them?

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    \$\begingroup\$ I really don't understand how it would be illegal. I don't know much about the legal aspects of using bluetooth serial commands. The only thing that might make it illegal is if it requires a license and you don't have it. After googling it, you can see that multiple people have incorporated bluetooth serial commands in their projects. I am pretty sure that it isn't illegal(but you should really do some more research just in case). I don't have a sure answer so I made this a comment and not an answer. \$\endgroup\$ – zack1544 Nov 8 '15 at 20:28
  • \$\begingroup\$ @zack1544 and do you know if it is possible to listen for those commands with a serial terminal like cutecom? \$\endgroup\$ – Rui Lima Nov 8 '15 at 20:47
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    \$\begingroup\$ This might be a better question for law.stackexchange.com but my understanding is the DMCA specifically allows reverse-engineering for purposes like this. \$\endgroup\$ – PeterJ Nov 18 '15 at 0:52


I'm not a lawyer, but I am a tech-sector executive that deals with this issue regularly.

It's copyright, not DMCA

You are just figuring out (reverse-engineering) their API (e.g. Bluetooth command set) and then using it with your own program. Up until 2014, this was a widely recognized and protected safe practice. API's were considered to be ineligible for patent or copyright protections.

That all changed with Oracle's victory in its case against Google (Oracle v. Google). The courts ruled in Oracle's favor effectively reversing over 50 years of precedent and allowing API's to be copyrighted. An appeal to the US Supreme Court in 2015 was summarily rejected, forcing the case back to a lower court -- so still somewhat up in the air.

After losing on the "copyrights shouldn't apply to API's" argument, Google fell back to the Fair Use Doctrine as a defense and is expected to prevail. The problem is that now the burden shifts to the user to prove fair use.

In your case, you might argue:

  • The use enables the creation of new technologies
  • You are using an insignificant percentage of the API
  • Your use is commentary on the API's design and application to wider purposes
  • Your use is educational for yourself or other developers

Practically... just do it

If you're not going to sell (or otherwise profit) from your project, then you are basically at near-zero risk. No one in their right mind would sue you over this. Worst-case, they'll just ask you to stop -- and if you do, the problem goes away.

Even if you are going to sell your project, since it helps sell their hardware, they will be strongly incentivised to leave you alone (assuming your sales don't cannibalize theirs).


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