Simone Seagle

Simone Seagle

Independent Web and Educational Software Developer

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Reading bluetooth data using Node.js on a Raspberry Pi

Reading bluetooth data using Node.js on a Raspberry Pi

April 28, 2016 Simone Seagle

If I were going to give Linux a tagline, it would be "Easier said than done." I thought that once I had gotten the USB combo dongle working in the last post, it would be trivial to get my Node.js application working on the Pi, but I was wrong.

On my mac, I was able to listen to the output of my Bluetooth device via a serial port with no extra work, but now I have to figure out how to get the same setup on the Pi.

I found this article that talks about how to set up rfcomm to set up a serial channel for the Bluetooth. I'm going to follow it. One issue I found with this article is that it tells you to type

sudo rfcomm connect 0

But that is missing arguments. It should be:

sudo rfcomm connect 0 AA:BB:CC:DD:EE:FF

Where you'd put your device's actual mac address in. I did that and it claimed to be connected, but it held one thread open on the terminal so I couldn't also run my Node.js app. I tried putting that in a bash script and then running Node in the same terminal window, but that didn't work. What worked was a pretty lame hack where I just opened two terminal windows. And then great success happened! I was able to start the server and then see the output locally on my machine.

And then life happened. I think the 9V battery on my KL46Z is almost dead because I wasn't getting enough juice for the Bluetooth card to work. That thing must really need a lot of power.

Finally, my husband pointed out that I really should put the units and scale on the graph.

So what's left to do before calling this project done?

  1. Figure out how to open up two threads in a bash script to make life easy
  2. Add scale to the graph

And what should I add for much improvement?

  1. Figure out how to have the rfcomm start up automatically when the right Bluetooth device appears
  2. Make my bash script start as soon as the Pi starts up