It kept going well, but it suddenly says error 515

newpro_copy_1 (7).aia (237.9 KB)

i want to die..

Translation error?

they sat Not connected to a Bluetooth device
Earlier, the Bluetooth list came out, it was connected, and I received information well, but now the list doesn't come up at al

Has the environment changed? There are a lot of reasons why a Bluetooth signal may not be received.

ProfessorCad: Tips & Tricks Cannot Build/Install/Run APK

Note, when you have a connection, one of your buttons sends and then trys to receive immediately. That's asking for trouble. Think of the Bluetooth signal as a water pipe. The water can flow in one direction at a time.

no!!!!so sad ,,,
nothing has changed :frowning:

Something has changed - you have not checked thoroughly. Are all your wires in good contact? Is your microcontroller getting sufficient power? Have you ensured the microcontroller does not overheat? Is Bluetooth switched on, both devices? You don't have an "on error" block in your App code. Is your microcontroller Sketch sending data to the Arduino Serial Monitor? If so, you can expand that with bug-tracking messages throughout the Sketch.

Note that error 515 means "not connected to a Bluetooth device", so that's a good clue. The "on error " Block may well reveal why.

Your component naming is terrible! This makes it difficult for others to understand your code.

ProfessorCad: Tips & Tricks GUI Layout and Component Naming

You can give the App a little bit more time to scan for devices by using a clock timer:

Capture App Errors

okay i'll try it!
thank you so much!!
thank you :slight_smile:

In case your version of Android requires Location to be switched on, drag a Location Component into Screen bluetooth.

Are you checking that Bluetooth is switched on (phone and microcontroller) before attempting anything else?

maybe it's runtime error

That would usually mean the version of Android does not "know" that permission. Try disabling the permission request for BluetoothScan.

Capture App Error Messages:

Other bits:

What is the Make, Model, Android Version and Bluetooth Version of your phone?

What is the Make, Model and Bluetooth Version of your microcontroller (or Bluetooth module)

See also here:

Your Project has the BLE extension but does not use BLE.
If you include Anke's extension 'GetApiLevel', you can ensure that only permissions relevant to the version of Android running are requested.

Your Screen named 'bluetooth' - this is not a good way to name screens because it does not identify it as a screen. 'Screen_Bluetooth' would have been better....... oh well.