我正在尝试将飞行时间传感器（VL53L0X）数据（通过蓝牙通过ESP32开发板通过蓝牙）发送至我在Android Studio中开发的android应用，但无法连接到开发板上一些理由。我对Android开发和微控制器还是有点菜鸟。我将非常感谢我所能提供的所有帮助。
尝试通过运行 bluetoothSocket.connect（）; 连接到开发板时 我收到此异常： java.io.IOException：读取失败，套接字可能关闭或超时，读取ret：-1
我认为问题出在UUID，但我不确定100％。
这是android studio代码：
package fi.jamk.tof;
import androidx.appcompat.app.AppCompatActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Set;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private boolean showingBtnText = false;
private static TextView textViewStatus, textViewDistance, textViewPaired;
private final static int REQUEST_ENABLE_BT = 1;
private static final int REQUEST_DISCOVER_BT = 0;
private static BluetoothAdapter bluetoothAdapter;
private static BluetoothSocket bluetoothSocket;
private static BluetoothDevice bluetoothDevice;
static final UUID myUUID = UUID.fromString("65a8c5ed-3a5b-4f53-8b59-26277adcb1de");
static final UUID serviceUUID = UUID.fromString("6E400001-B5A3-F393-E0A9-E50E24DCCA9E");
private final static String MAC = "30:AE:A4:1F:A0:2A";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textViewStatus = (TextView) findViewById(R.id.textViewStatus);
textViewDistance = (TextView) findViewById(R.id.textViewDistance);
textViewPaired = (TextView) findViewById(R.id.textViewPaired);
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = bluetoothManager.getAdapter();
if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
textViewStatus.setText("Bluetooth is not enabled, enabling bluetooth");
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
textViewPaired.setText("Paired devices:");
Set<BluetoothDevice> devices = bluetoothAdapter.getBondedDevices();
for(BluetoothDevice device : devices){
textViewPaired.append("\nDevice: " + device.getName() + ", " + device);
}
try{
bluetoothDevice = bluetoothAdapter.getRemoteDevice(MAC);
bluetoothSocket = bluetoothDevice.createInsecureRfcommSocketToServiceRecord(myUUID);
bluetoothSocket.connect();
} catch (IOException ex){
Toast toast = Toast.makeText(this, ex.toString(), Toast.LENGTH_LONG);
toast.show();
}
final Button btnScan = (Button) findViewById(R.id.btnScan);
btnScan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(showingBtnText == true){
btnScan.setText("Scan");
showingBtnText = false;
textViewStatus.setText("Scan complete");
int distance = getData();
textViewDistance.setText(distance);
} else {
btnScan.setText("Stop Scanning");
showingBtnText = true;
textViewStatus.setText("Scanning...");
}
}
});
}
private int getData(){
int distance;
if (bluetoothSocket != null) {
try {
InputStream data = bluetoothSocket.getInputStream();
String dataToString = getStringFromInputStream(data);
distance = Integer.parseInt(dataToString);
return distance;
} catch (IOException e) {
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_LONG).show();
return 0;
}
} else{
return 0;
}
}
private static String getStringFromInputStream(InputStream is) {
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String line;
try {
br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
sb.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
}
这是Arduino IDE代码：
/* This example shows how to get single-shot range
measurements from the VL53L0X. The sensor can optionally be
configured with different ranging profiles, as described in
the VL53L0X API user manual, to get better performance for
a certain application. This code is based on the four
"SingleRanging" examples in the VL53L0X API.
The range readings are in units of mm. */
#include <Wire.h>
#include <VL53L0X.h>
#include <MedianFilter.h>
#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>
#include <BLE2902.h>
BLECharacteristic *pCharacteristic;
bool deviceConnected = false;
float txValue = 0;
const int readPin = 32; // Use GPIO number. See ESP32 board pinouts
const int LED = 2; // Could be different depending on the dev board. I used the DOIT ESP32 dev board.
//std::string rxValue; // Could also make this a global var to access it in loop()
// See the following for generating UUIDs:
// https://www.uuidgenerator.net/
//#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
#define SERVICE_UUID "65a8c5ed-3a5b-4f53-8b59-26277adcb1de"
#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define CHARACTERISTIC_UUID_TX "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
class MyServerCallbacks: public BLEServerCallbacks {
void onConnect(BLEServer* pServer) {
deviceConnected = true;
};
void onDisconnect(BLEServer* pServer) {
deviceConnected = false;
}
};
class MyCallbacks: public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
std::string rxValue = pCharacteristic->getValue();
if (rxValue.length() > 0) {
Serial.println("*********");
Serial.print("Received Value: ");
for (int i = 0; i < rxValue.length(); i++) {
Serial.print(rxValue[i]);
}
Serial.println("*********");
}
}
};
VL53L0X sensor;
MedianFilter test(10, 0);
// Uncomment this line to use long range mode. This
// increases the sensitivity of the sensor and extends its
// potential range, but increases the likelihood of getting
// an inaccurate reading because of reflections from objects
// other than the intended target. It works best in dark
// conditions.
//#define LONG_RANGE
// Uncomment ONE of these two lines to get
// - higher speed at the cost of lower accuracy OR
// - higher accuracy at the cost of lower speed
//#define HIGH_SPEED
//#define HIGH_ACCURACY
int val;
void setup()
{
Serial.begin(115200);
Wire.begin();
pinMode(LED, OUTPUT);
// Create the BLE Device
BLEDevice::init("ESP32 UART Test"); // Give it a name
// Create the BLE Server
BLEServer *pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID_TX,
BLECharacteristic::PROPERTY_NOTIFY
);
pCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pCharacteristic = pService->createCharacteristic(
CHARACTERISTIC_UUID_RX,
BLECharacteristic::PROPERTY_WRITE
);
pCharacteristic->setCallbacks(new MyCallbacks());
// Start the service
pService->start();
// Start advertising
pServer->getAdvertising()->start();
Serial.println("Waiting a client connection to notify...");
sensor.init();
sensor.setTimeout(500);
#if defined LONG_RANGE
// lower the return signal rate limit (default is 0.25 MCPS)
sensor.setSignalRateLimit(0.1);
// increase laser pulse periods (defaults are 14 and 10 PCLKs)
sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodPreRange, 18);
sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodFinalRange, 14);
#endif
#if defined HIGH_SPEED
// reduce timing budget to 20 ms (default is about 33 ms)
sensor.setMeasurementTimingBudget(20000);
#elif defined HIGH_ACCURACY
// increase timing budget to 200 ms
sensor.setMeasurementTimingBudget(200000);
#endif
}
void loop()
{
if (deviceConnected){
val = sensor.readRangeSingleMillimeters();
test.in(val);
val = test.out();
pCharacteristic->setValue(val);
pCharacteristic->notify();
//Serial.print(val);
if (sensor.timeoutOccurred()) { Serial.print(" TIMEOUT"); }
Serial.println();
}
}