BLE UART app for Android. It sends statusbar notification (>20bytes) to a Bluetooth 4.0 module.

This project is maintained by no-go

Android-nRF-UART - My Mod !!

nRF UART app can be used to connect to Bluetooth® Smart devices running a custom UART service. When connected, the app can send and receive ASCII and UTF-8 text strings. This source code can be compiled with Android Studio and Gradle.

Get a PDF (german) about my UART Smartwatch Project from the Slides/ folder: Get Slides


This fork of the Android-nRF-UART App has this modifikations:


What did I do?

the arduino code

I write a small Terminal firmware for the Arduino. Serial chars are printed to the SSD1306 OLED Display (max. 168, then refresh the display).

a small oLed Terminal code


a small oLed Terminal circuit with bluetooth

Android App (thanks to Nordic Semicoductor to make it Open Source!)

I change the maxLength of the sendText object in res/layout/main.xml (Android App) from 20 to 168.

enlarge the text field

I simplify the sending method of to make it easier to understand …

UART BLE Service - RX simplify

… and make it a bit complicated again. This loop sends the bytes (max 20) in 60ms intervalls:

send more than 20 bytes

I have to add a try/catch:

try and catch

I do some modifications at the to of to work with a HM-10 (not the realy good nordic Semiconductor!) Module:

Modifications from nRF to HM-10

Now, I modify the AndroidManifest.xml and add the Notfication Service to listen to the status bar notifications.

Add new Notification Listener and permissions to Mainfest

I modify the app/build.gradle to build the App for Android 4.4 (19) instead for Android 4.3 (18). On Android 4.4 it is easier to access the notification text. (do not forget to Sync the Project).

change API level

I create a NotificatonService.class and get new status bar notifications. I remove (do a return;) the uninteressting ones. After a have some message, I broadcast this message from the Notification Service to the hole Android System with an intent object.

get new status bar notification

In the Main App Activity ( we need a BroadcastReceiver to handle this intent. I call this class NotificationReceiver.

Receive Broadcasts

I need an instance of this new NotificationReceiver at the top of the I call it nReceiver:

Finaly, I have to add a filter and register this nReceiver, to listen to “heuteTollesWetter.NOTIFICATION” intents. I am not sure, if you realy add this filter - I filter this intents via getAction() in the NotificationReceiver, too.

You have to add the Code in the onCreate() methode:

register receiver

Permissions to Notifications

The App whats to get this permisson: BIND_NOTIFICATION_LISTENER_SERVICE. To permit these permissions, you have to give it via your settings on your mobile:

give permissions to read all notifications