Sending data to Arduino 101

[cloud2828]

I would like to start off by saying I am not a very experienced programmer and I only have base knowledge of Java and Android Studio. Furthermore, I have no experience in Bluetooth communication or BLE. I've done a lot of research, went through some of the tutorials on here and I would like to know how I can send data to my Arduino 101 to simply turn on a LED. I've used the nRF Connect app to do this and it works fine but my project requires me to make my own android app to do this. A simple solution would be helpful since I am pressed for time. I'd also like to know if I'm on the right path, from what I understand, the app would be the GATT Client and the Arduino 101 is the GATT server. If I want to send data to the Arduino to turn on an LED, is it required for me to create a custom service? How exactly does it work, do I read the service from the Arduino then write something to it to turn on the LED, or do I have to create a custom service that will write to the Arduino. A breakdown of the process of what happens when you use the GATT Client to send a notification to the GATT server for the Arduino to know to turn on the LED would also help in clarifying things. My knowledge on BLE is in pieces as of now. Thanks in advance.

Edit: An answer to any of my questions would be really helpful in clarifying things as I am unable to move on at the moment.

[Bjørn Kvaale]

I think this link gives a great example of how to toggle the LED on/off using an Android app. I would start off with that first. Seems like they use html to code, so it shouldn't be all too difficult. Good luck!

[Bjørn Kvaale]

Normally, the server is the device that contains data which the client can then read. In your case, there is no data to read, but it is correct that the arduino 101 would be the server and the app is the client.

[cloud2828]

There is no data being read by the client because it is just sending a message to the server to invoke a response right?

[cloud2828]

This was helpful in understanding what I need to do but a bit too simplified as the library they used had functions that turned on the LED but I'd like to know what the function actually contains. If I knew this, I do believe I'd be able to translate the code to Java using Android Studio. On another note, I would like to know if the Google example for the GATT client (github.com/.../README.md) can be modified to do what I need to do, if so, are there simplified libraries available like the one in the link you sent for Java (Android Studio)?

[Bjørn Kvaale]

I would recommend either looking at the Blinky examples in the SDK found under /examples/peripheral/blinky and /examples/ble_peripheral/blinky, as well as the Nordic Thingy:52 source code found on Github. The Nordic Thingy source code is the source code used to write the Android application. As the Thingy has an LED, it should be quite easy for you to locate how they turn the LED on/off & just slightly modify that functionality to your needs.