I'm trying to create an App which can receive data and send data to the microcontroller (ESP32). But for some reason, I'm unable to receive data from microcontroller successfully.
The app is written in Kotlin, and I already tried some examples mentioned on StackOverflow, but none of them actually works on my code. I can successfully send data to the microcontroller via Bluetooth, but I can't receive data from Bluetooth. (The method I used in the microcontroller is just simply "ESP_BT.println("Check");"
In the code snippet, the function relates to my receiving data is called "receiveBluetooth"
class ControlActivity: AppCompatActivity() {
companion object {
val myUUID: UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB")
var myBluetoothSocket: BluetoothSocket? = null
lateinit var myProgress: ProgressDialog
lateinit var myBluetoothAdapter: BluetoothAdapter
var myIsConnected: Boolean = false
lateinit var myAddress: String
val mmInStream: InputStream? = null
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.control_layout)
myAddress = intent.getStringExtra(SelectDeviceActivity.EXTRA_ADDRESS)
ConnectToDevice(this).execute()
val btnShow = findViewById<Button>(R.id.btnShow)
var inputRPM: String
//Read in value and store it as String
btnShow.setOnClickListener{
inputRPM = receiveInput()
sendCommand(inputRPM)
}
//Read RPM from microcontroller (bluetooth)
val showCountTextView = findViewById<TextView>(R.id.textView)
btnRefresh.setOnClickListener {
//showCountTextView.text = receiveBluetooth()
receiveBluetooth(showCountTextView)
}
control_disconnect.setOnClickListener{
disconnect()
}
}
private fun receiveInput(): String {
val input = findViewById<EditText>(R.id.editText)
return input.text.toString()
}
private fun sendCommand(input: String) {
if (myBluetoothSocket != null) {
try{
myBluetoothSocket!!.outputStream.write(input.toByteArray())
} catch (e: IOException) {
e.printStackTrace()
}
}
}
private fun receiveBluetooth(input: TextView) {
val buffer = ByteArray(256)
val bytes:Int
var tmpIn: InputStream? = null
if (myBluetoothSocket != null) {
try {
tmpIn = myBluetoothSocket!!.inputStream
val mmInStream = DataInputStream(tmpIn)
bytes = mmInStream.read(buffer)
val readMessage = String(buffer, 0, bytes)
input.text = readMessage
//input.text="123"
} catch (e:IOException) {
e.printStackTrace()
}
}
}
private fun disconnect() {
if (myBluetoothSocket != null) {
try {
myBluetoothSocket!!.close()
myBluetoothSocket = null
myIsConnected = false
} catch (e: IOException) {
e.printStackTrace()
}
}
finish()
}
private class ConnectToDevice(c: Context) : AsyncTask<Void, Void, String> () {
private var connectSuccess: Boolean = true
private val context: Context
init {
this.context = c
}
override fun onPreExecute() {
super.onPreExecute()
myProgress = ProgressDialog.show(context, "Connecting", "Please wait")
}
override fun doInBackground(vararg params: Void?): String? {
try {
if (myBluetoothSocket == null || !myIsConnected) {
myBluetoothAdapter = BluetoothAdapter.getDefaultAdapter()
val device: BluetoothDevice = myBluetoothAdapter.getRemoteDevice(myAddress)
myBluetoothSocket = device.createInsecureRfcommSocketToServiceRecord(myUUID)
BluetoothAdapter.getDefaultAdapter().cancelDiscovery()
myBluetoothSocket!!.connect()
}
} catch (e: IOException) {
connectSuccess = false
e.printStackTrace()
}
//Needs be fixed
return null
}
override fun onPostExecute(result: String?) {
super.onPostExecute(result)
if (!connectSuccess) {
Log.i("data", "couldn't connect")
} else {
myIsConnected = true
}
myProgress.dismiss()
}
}
}
I expect the text will show exactly "Check", but instead, my text will only show the initial value that I assigned.
