我有一个连接到Arduino Uno和HC-06蓝牙模块的ECG模块，该模块以100 Hz的频率测量ECG信号，并每10毫秒将6字节数据发送到Android应用程序中。但是，我无法实现每秒接收100个样本。
这是我的Arduino代码：
#include <SoftwareSerial.h>
SoftwareSerial myBT(2, 3);
void setup() {
myBT.begin(115200);
Serial.begin(115200);
pinMode(A0, OUTPUT);
}
char cmd;
int ECG;
void loop()
{
if(myBT.available()>0)
{
cmd = myBT.read();
while(cmd = 'r')
{
ECG = ((ECG+1)%1023);
float Volt = (float)ECG*5.0/1023.0;
myBT.print("s"+String(Volt,2));
delay(10);
}
}
}
这是我的Android Java代码：
package com.example.mscale;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.annotation.SuppressLint;
import android.app.ActivityManager;
import android.app.AlertDialog;
import android.app.Dialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.graphics.Color;
import android.icu.text.UnicodeSetSpanner;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.SystemClock;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.LegendRenderer;
import com.jjoe64.graphview.series.DataPoint;
import com.jjoe64.graphview.series.LineGraphSeries;
import com.jjoe64.graphview.series.Series;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.UUID;
public class MonitorActivity extends AppCompatActivity {
private final String TAG = "MonitorActivity";
//Stuffs
GraphView graphx;
Button recordButton;
TextView statusBtTxt, KilogramTxt;
//Bluetooth Stuffs
private static final int REQUEST_ENABLE_BT = 1;
BluetoothAdapter bluetoothAdapter;
private ArrayList<String> mDeviceList;
private String pairedAddres;
ArrayAdapter<String> adapter;
private BluetoothSocket mBluetoothSocket;
public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
protected static final int SUCESS_CONNECT = 0;
protected static final int MESSAGE_READ = 1;
protected static final int MESSAGE_WRITE = 2;
private boolean recording = false;
/* @Override
public void onBackPressed() {
// TODO Auto-generated method stub
if (Bluetooth.connectedThread != null) {
Bluetooth.connectedThread.write("Q");}//Stop streaming
super.onBackPressed();
}*/
@SuppressLint("HandlerLeak")
public Handler mHandler = new Handler() {
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case SUCESS_CONNECT:
statusBtTxt.setText("Connected");
recording = true;
break;
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, 5); // create string from bytes array
statusBtTxt.setText(strIncom);
Log.d(TAG, strIncom);
/*if (strIncom.indexOf("s") == 3) {
Log.d(TAG, strIncom);
strIncom = strIncom.replace("s", "");
if(isFloatNumber(strIncom)){
}
}else Log.d(TAG, "The s is not where it should be!");*/
break;
case MESSAGE_WRITE:
ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket) msg.obj);
connectedThread.write("r");
break;
}
}
};
public boolean isFloatNumber(String num) {
//Log.d("checkfloatNum", num);
try {
Double.parseDouble(num);
} catch (NumberFormatException nfe) {
return false;
}
return true;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
hideStatusbar();
setContentView(R.layout.activity_monitor);
findIDStuff();
plotting();
System.gc();
recordButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (recording == false) {
bluetoothManagement();
} else {
ConnectedThread connectedThread = new ConnectedThread(mBluetoothSocket);
connectedThread.write("r");
connectedThread.start();
}
}
});
}
//Find ID of Stuffs
private void findIDStuff() {
recordButton = findViewById(R.id.recordBtn);
//graphx = (GraphView) findViewById(R.id.graph);
statusBtTxt = findViewById(R.id.btStatusTxt);
KilogramTxt = findViewById(R.id.kiloTxt);
}
//Bluetooth management
private void bluetoothManagement() {
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (!bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
} else {
//Do sth
pairedBtDevices();
}
}
//Graph plotting
private void plotting() {
}
//Hide status bar
private void hideStatusbar() {
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
}
//Paired Bluetooth device
private void pairedBtDevices() {
// Register for broadcasts when a device is discovered.
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(receiver, filter);
Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
for (BluetoothDevice device : pairedDevices) {
String module = "ECG_Module";
if (device.getName().equals(module)) {
pairedAddres = device.getAddress();
}
}
bluetoothAdapter.startDiscovery();
//Log.d(TAG, String.valueOf(mPairedDeviceList));
} else {
statusBtTxt.setText("No paired");
}
}
// Create a BroadcastReceiver for ACTION_FOUND.
private final BroadcastReceiver receiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();
mDeviceList = new ArrayList<String>();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
String module = "ECG_Module";
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (device.getName() != null && device.getName().equalsIgnoreCase(module) && device.getAddress() != null && device.getAddress().equalsIgnoreCase(pairedAddres)) {
mDeviceList.add(device.getName() + "\n" + device.getAddress());
bluetoothAdapter.cancelDiscovery();
open_dialog();
}
} else if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
statusBtTxt.setText("Start Discovery...");
} else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
statusBtTxt.setText("End Discovery....");
}
}
};
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(receiver);
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Checks the orientation of the screen
if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show();
} else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show();
}
}
//Open dialog
public void open_dialog() {
final AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);
final View row = getLayoutInflater().inflate(R.layout.rowitem, null);
ListView mlistView = (ListView) row.findViewById(R.id.listviewBt);
final Button mBtnConnect = (Button) row.findViewById(R.id.conBtn);
Button mBtnCancel = (Button) row.findViewById(R.id.canBtn);
mlistView.setClickable(true);
adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, mDeviceList);
mlistView.setAdapter(adapter);
alertDialog.setView(row);
final AlertDialog dialog = alertDialog.create();
dialog.show();
mlistView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String mNames = (String) parent.getItemAtPosition(position);
final String[] mMacAddress = mNames.split("\\r?\\n");
mBtnConnect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
BluetoothDevice bluetoothDevice = bluetoothAdapter.getRemoteDevice(mMacAddress[1]);
ConnectThread connectThread = new ConnectThread(bluetoothDevice);
connectThread.start();
Context context = getApplicationContext();
Toast toast = Toast.makeText(context, "Connnecting to " + mMacAddress[1], Toast.LENGTH_SHORT);
toast.show();
dialog.hide();
} catch (Exception e) {
Context context = getApplicationContext();
Toast toast = Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT);
toast.show();
return;
}
}
});
}
});
mBtnCancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
dialog.hide();
}
});
}
//Connection Bluetooth
private class ConnectThread extends Thread {
private final BluetoothSocket mmSocket;
private final BluetoothDevice mmDevice;
public ConnectThread(BluetoothDevice device) {
// Use a temporary object that is later assigned to mmSocket
// because mmSocket is final.
BluetoothSocket tmp = null;
mmDevice = device;
try {
// Get a BluetoothSocket to connect with the given BluetoothDevice.
// MY_UUID is the app's UUID string, also used in the server code.
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
Log.e(TAG, "Socket's create() method failed", e);
}
mBluetoothSocket = tmp;
mmSocket = tmp;
}
public void run() {
// Cancel discovery because it otherwise slows down the connection.
bluetoothAdapter.cancelDiscovery();
try {
// Connect to the remote device through the socket. This call blocks
// until it succeeds or throws an exception.
mmSocket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and return.
try {
mmSocket.close();
Log.d(TAG, "Failed connection");
} catch (IOException closeException) {
Log.e(TAG, "Could not close the client socket", closeException);
}
return;
}
// The connection attempt succeeded. Perform work associated with
// the connection in a separate thread.
mHandler.obtainMessage(SUCESS_CONNECT, mmSocket).sendToTarget();
}
// Closes the client socket and causes the thread to finish.
public void cancel() {
try {
statusBtTxt.setText("Failed Connection");
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "Could not close the client socket", e);
}
}
}
class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
StringBuffer sbb = new StringBuffer();
public void run() {
// Keep listening to the InputStream until an exception occurs
byte[] buffer;
int bytes = 0;
try {
while(mmInStream.read() != (byte) 's')
{}
//Since we already read out the "s", we need to read 4 more bytes, to regain alignment.
mmInStream.read();
mmInStream.read();
mmInStream.read();
mmInStream.read();
//Now, the next byte read should be an "s".
} catch (IOException e) {
return;
}
while (true) {
try {
buffer = new byte[1024];
// Read from the InputStream
int totalRead = 0;
while(totalRead < 5)
{
bytes = mmInStream.read(buffer,totalRead,5-totalRead);
if(bytes==-1)
throw new IOException("EOS reached");
totalRead += bytes;
}
//Log.d("Obtain: ", String.valueOf(totalRead));
mHandler.obtainMessage(MESSAGE_READ, totalRead, -1, buffer).sendToTarget();
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write (String income){
try {
mmOutStream.write(income.getBytes());
} catch (IOException e) {
}
}
/* Call this from the main activity to shutdown the connection */
public void cancel () {
try {
mmSocket.close();
} catch (IOException e) {
}
}
}
}
Android中已传输的可变值和Logcat接收到的数据（没有myBT.print（“ \ n”）和Sensor输入）：
2020-01-22 13:12:22.369 28250-28250/com.example.mscale D/MonitorActivity: s0.01
2020-01-22 13:12:22.401 28250-28250/com.example.mscale D/MonitorActivity: s0.01
2020-01-22 13:12:22.421 28250-28250/com.example.mscale D/MonitorActivity: s0.02
2020-01-22 13:12:22.421 28250-28250/com.example.mscale D/MonitorActivity: s0.02
2020-01-22 13:12:22.422 28250-28250/com.example.mscale D/MonitorActivity: s0.03
2020-01-22 13:12:22.444 28250-28250/com.example.mscale D/MonitorActivity: s0.03
2020-01-22 13:12:22.454 28250-28250/com.example.mscale D/MonitorActivity: s0.04
2020-01-22 13:12:22.454 28250-28250/com.example.mscale D/MonitorActivity: s0.04
2020-01-22 13:12:22.454 28250-28250/com.example.mscale D/MonitorActivity: s0.05
2020-01-22 13:12:22.478 28250-28250/com.example.mscale D/MonitorActivity: s0.05
2020-01-22 13:12:22.488 28250-28250/com.example.mscale D/MonitorActivity: s0.06
2020-01-22 13:12:22.488 28250-28250/com.example.mscale D/MonitorActivity: s0.06
2020-01-22 13:12:22.514 28250-28250/com.example.mscale D/MonitorActivity: s0.07
2020-01-22 13:12:22.522 28250-28250/com.example.mscale D/MonitorActivity: s0.07
2020-01-22 13:12:22.522 28250-28250/com.example.mscale D/MonitorActivity: s0.08
2020-01-22 13:12:22.548 28250-28250/com.example.mscale D/MonitorActivity: s0.08
2020-01-22 13:12:22.555 28250-28250/com.example.mscale D/MonitorActivity: s0.09
2020-01-22 13:12:22.555 28250-28250/com.example.mscale D/MonitorActivity: s0.09
2020-01-22 13:12:22.572 28250-28250/com.example.mscale D/MonitorActivity: s0.10
2020-01-22 13:12:22.589 28250-28250/com.example.mscale D/MonitorActivity: s0.10
2020-01-22 13:12:22.589 28250-28250/com.example.mscale D/MonitorActivity: s0.11
2020-01-22 13:12:22.606 28250-28250/com.example.mscale D/MonitorActivity: s0.11
2020-01-22 13:12:22.623 28250-28250/com.example.mscale D/MonitorActivity: s0.12
2020-01-22 13:12:22.640 28250-28250/com.example.mscale D/MonitorActivity: s0.12
2020-01-22 13:12:22.641 28250-28250/com.example.mscale D/MonitorActivity: s0.13
2020-01-22 13:12:22.659 28250-28250/com.example.mscale D/MonitorActivity: s0.13
2020-01-22 13:12:22.673 28250-28250/com.example.mscale D/MonitorActivity: s0.14
2020-01-22 13:12:22.673 28250-28250/com.example.mscale D/MonitorActivity: s0.14
2020-01-22 13:12:22.674 28250-28250/com.example.mscale D/MonitorActivity: s0.15
2020-01-22 13:12:22.700 28250-28250/com.example.mscale D/MonitorActivity: s0.15
2020-01-22 13:12:22.707 28250-28250/com.example.mscale D/MonitorActivity: s0.16
2020-01-22 13:12:22.707 28250-28250/com.example.mscale D/MonitorActivity: s0.16
2020-01-22 13:12:22.724 28250-28250/com.example.mscale D/MonitorActivity: s0.17
2020-01-22 13:12:22.724 28250-28250/com.example.mscale D/MonitorActivity: s0.17
2020-01-22 13:12:22.743 28250-28250/com.example.mscale D/MonitorActivity: s0.18
2020-01-22 13:12:22.758 28250-28250/com.example.mscale D/MonitorActivity: s0.18
2020-01-22 13:12:22.758 28250-28250/com.example.mscale D/MonitorActivity: s0.19
2020-01-22 13:12:22.778 28250-28250/com.example.mscale D/MonitorActivity: s0.19
2020-01-22 13:12:22.793 28250-28250/com.example.mscale D/MonitorActivity: s0.20
2020-01-22 13:12:22.794 28250-28250/com.example.mscale D/MonitorActivity: s0.20
2020-01-22 13:12:22.815 28250-28250/com.example.mscale D/MonitorActivity: s0.21
2020-01-22 13:12:22.828 28250-28250/com.example.mscale D/MonitorActivity: s0.21
2020-01-22 13:12:22.828 28250-28250/com.example.mscale D/MonitorActivity: s0.22
2020-01-22 13:12:22.829 28250-28250/com.example.mscale D/MonitorActivity: s0.22
2020-01-22 13:12:22.858 28250-28250/com.example.mscale D/MonitorActivity: s0.22
2020-01-22 13:12:22.877 28250-28250/com.example.mscale D/MonitorActivity: s0.23
2020-01-22 13:12:22.878 28250-28250/com.example.mscale D/MonitorActivity: s0.23
2020-01-22 13:12:22.878 28250-28250/com.example.mscale D/MonitorActivity: s0.24
2020-01-22 13:12:22.897 28250-28250/com.example.mscale D/MonitorActivity: s0.24
2020-01-22 13:12:22.911 28250-28250/com.example.mscale D/MonitorActivity: s0.25
2020-01-22 13:12:22.912 28250-28250/com.example.mscale D/MonitorActivity: s0.25
2020-01-22 13:12:22.929 28250-28250/com.example.mscale D/MonitorActivity: s0.26
2020-01-22 13:12:22.929 28250-28250/com.example.mscale D/MonitorActivity: s0.26
2020-01-22 13:12:22.945 28250-28250/com.example.mscale D/MonitorActivity: s0.27
2020-01-22 13:12:22.964 28250-28250/com.example.mscale D/MonitorActivity: s0.27
2020-01-22 13:12:22.965 28250-28250/com.example.mscale D/MonitorActivity: s0.28
2020-01-22 13:12:22.980 28250-28250/com.example.mscale D/MonitorActivity: s0.28
2020-01-22 13:12:22.998 28250-28250/com.example.mscale D/MonitorActivity: s0.29
2020-01-22 13:12:23.013 28250-28250/com.example.mscale D/MonitorActivity: s0.29
2020-01-22 13:12:23.013 28250-28250/com.example.mscale D/MonitorActivity: s0.30
2020-01-22 13:12:23.033 28250-28250/com.example.mscale D/MonitorActivity: s0.30
2020-01-22 13:12:23.046 28250-28250/com.example.mscale D/MonitorActivity: s0.31
2020-01-22 13:12:23.046 28250-28250/com.example.mscale D/MonitorActivity: s0.31
2020-01-22 13:12:23.047 28250-28250/com.example.mscale D/MonitorActivity: s0.32
2020-01-22 13:12:23.069 28250-28250/com.example.mscale D/MonitorActivity: s0.32
2020-01-22 13:12:23.079 28250-28250/com.example.mscale D/MonitorActivity: s0.33
2020-01-22 13:12:23.080 28250-28250/com.example.mscale D/MonitorActivity: s0.33
2020-01-22 13:12:23.104 28250-28250/com.example.mscale D/MonitorActivity: s0.34
2020-01-22 13:12:23.115 28250-28250/com.example.mscale D/MonitorActivity: s0.34
2020-01-22 13:12:23.115 28250-28250/com.example.mscale D/MonitorActivity: s0.35
2020-01-22 13:12:23.116 28250-28250/com.example.mscale D/MonitorActivity: s0.35
2020-01-22 13:12:23.139 28250-28250/com.example.mscale D/MonitorActivity: s0.36
2020-01-22 13:12:23.149 28250-28250/com.example.mscale D/MonitorActivity: s0.36
2020-01-22 13:12:23.149 28250-28250/com.example.mscale D/MonitorActivity: s0.37
2020-01-22 13:12:23.178 28250-28250/com.example.mscale D/MonitorActivity: s0.37
2020-01-22 13:12:23.198 28250-28250/com.example.mscale D/MonitorActivity: s0.38
2020-01-22 13:12:23.198 28250-28250/com.example.mscale D/MonitorActivity: s0.38
2020-01-22 13:12:23.215 28250-28250/com.example.mscale D/MonitorActivity: s0.39
2020-01-22 13:12:23.216 28250-28250/com.example.mscale D/MonitorActivity: s0.39
2020-01-22 13:12:23.216 28250-28250/com.example.mscale D/MonitorActivity: s0.40
2020-01-22 13:12:23.235 28250-28250/com.example.mscale D/MonitorActivity: s0.40
2020-01-22 13:12:23.248 28250-28250/com.example.mscale D/MonitorActivity: s0.41
2020-01-22 13:12:23.249 28250-28250/com.example.mscale D/MonitorActivity: s0.41
2020-01-22 13:12:23.266 28250-28250/com.example.mscale D/MonitorActivity: s0.42
2020-01-22 13:12:23.284 28250-28250/com.example.mscale D/MonitorActivity: s0.42
2020-01-22 13:12:23.299 28250-28250/com.example.mscale D/MonitorActivity: s0.43
2020-01-22 13:12:23.299 28250-28250/com.example.mscale D/MonitorActivity: s0.43
2020-01-22 13:12:23.319 28250-28250/com.example.mscale D/MonitorActivity: s0.43
2020-01-22 13:12:23.336 28250-28250/com.example.mscale D/MonitorActivity: s0.44
2020-01-22 13:12:23.336 28250-28250/com.example.mscale D/MonitorActivity: s0.44
2020-01-22 13:12:23.355 28250-28250/com.example.mscale D/MonitorActivity: s0.45
2020-01-22 13:12:23.367 28250-28250/com.example.mscale D/MonitorActivity: s0.45
2020-01-22 13:12:23.386 28250-28250/com.example.mscale D/MonitorActivity: s0.46
2020-01-22 13:12:23.386 28250-28250/com.example.mscale D/MonitorActivity: s0.46
2020-01-22 13:12:23.387 28250-28250/com.example.mscale D/MonitorActivity: s0.47
2020-01-22 13:12:23.387 28250-28250/com.example.mscale D/MonitorActivity: s0.47
2020-01-22 13:12:23.417 28250-28250/com.example.mscale D/MonitorActivity: s0.48
2020-01-22 13:12:23.435 28250-28250/com.example.mscale D/MonitorActivity: s0.48
2020-01-22 13:12:23.436 28250-28250/com.example.mscale D/MonitorActivity: s0.49
2020-01-22 13:12:23.436 28250-28250/com.example.mscale D/MonitorActivity: s0.49
2020-01-22 13:12:23.457 28250-28250/com.example.mscale D/MonitorActivity: s0.50
2020-01-22 13:12:23.474 28250-28250/com.example.mscale D/MonitorActivity: s0.50
2020-01-22 13:12:23.474 28250-28250/com.example.mscale D/MonitorActivity: s0.51
2020-01-22 13:12:23.474 28250-28250/com.example.mscale D/MonitorActivity: s0.51
2020-01-22 13:12:23.501 28250-28250/com.example.mscale D/MonitorActivity: s0.52
2020-01-22 13:12:23.501 28250-28250/com.example.mscale D/MonitorActivity: s0.52
2020-01-22 13:12:23.519 28250-28250/com.example.mscale D/MonitorActivity: s0.53
2020-01-22 13:12:23.540 28250-28250/com.example.mscale D/MonitorActivity: s0.53
2020-01-22 13:12:23.541 28250-28250/com.example.mscale D/MonitorActivity: s0.54
2020-01-22 13:12:23.541 28250-28250/com.example.mscale D/MonitorActivity: s0.54
2020-01-22 13:12:23.553 28250-28250/com.example.mscale D/MonitorActivity: s0.55
2020-01-22 13:12:23.573 28250-28250/com.example.mscale D/MonitorActivity: s0.55
2020-01-22 13:12:23.587 28250-28250/com.example.mscale D/MonitorActivity: s0.56
2020-01-22 13:12:23.587 28250-28250/com.example.mscale D/MonitorActivity: s0.56
最佳答案
您的蓝牙模块可能没问题。您看到的性能问题很可能是协议实现方面的问题：即，s字符不在您期望的位置。造成这种情况的原因有很多，所以让我们一一讲解它们：
心电图的价值
请注意，analogRead()的返回值的范围是0到1023（docs），对应于0V到Vref的范围。假设您的Vref为5V，则ECG的3.3V输出将导致analogRead()返回675。因此，实际上，ECG的范围可能从0到675。这就是为什么您拥有以下缩放逻辑的原因：
float Volt = (float)ECG*5.0/1023.0;
这会将ADC读数转换回电压。
缩放逻辑的精度
如果
ECG是5，则Volt将是0.024437929。这违反了您的假设，即Volt始终是四个字符的浮点数，并且导致您的s字符未对齐。Logcat问题
跳过的消息：这不是由于BT连接故障。这是因为您将比计划多的消息放入一个缓冲区。
mmInStream.read(buffer)将尝试读取多达1024个字节；这意味着它可能会抓取多条消息。但是，如果您在缓冲区中收到多个消息，那么您将只处理第一个消息。损坏的消息：例如，
s0.����。这是因为mmInStream.read(buffer)仅读取3个字节，但是您假定它读取为5。您会发现，read()在至少有1个新字节可用时立即返回一个值。这并不意味着它已读取您想要的所有内容。在这种情况下，最后2个字节已进行单位化（0），但无论如何您都尝试将其转换为String。邮件未对齐：这与损坏的邮件具有相同的根本原因。请注意，logcat中的下一行是
15s0.。这是因为第15条消息（s0.15）在中间被拆分。然后，第16条消息（s0.）的一部分将附加到末尾，因为现在您的对齐方式已关闭。由于套接字时序的怪异，仅在下一行重新获得了重新对齐。解决所有这3个问题的方法是确保
read()块，直到它精确读取5个字节为止（请参见“修复＃2”）。修复＃1
强制所有字符串转换产生正好4个字符（docs）：
myBT.print("s"+String(Volt,2)); //2 decimal places works out to 4 characters total, for your input range.
修复＃2
确保所有BT套接字读取的长度均为5个字节。
buffer = new byte[1024];
// Read from the InputStream
int totalRead = 0;
while(totalRead < 5)
{
bytes = mmInStream.read(buffer,totalRead,5-totalRead);
if(bytes==-1)
throw new IOException("EOS reached");
totalRead += bytes;
}
另外，您可以使用为此目的而设计的功能，例如DataInputStream.readFully()。
修复＃3
由于尚不清楚的原因，您发送的消息相对于收到的消息具有固定的偏移量。可能是因为启动条件有问题；您的Arduino可能正在将数据发送到BT模块，而不知道是否已连接。因此，在实际建立BT连接的那一刻，它开始在消息中间而不是在开始时发送。为了解决这个问题并重新获得对齐，我建议使用如下代码：
// Keep listening to the InputStream until an exception occurs
byte[] buffer;
int bytes = 0;
try {
while(mmInStream.read() != (byte) 's') //TODO: Handle "-1" case
{}
//Since we already read out the "s", we need to read 4 more bytes, to regain alignment.
mmInStream.read();
mmInStream.read();
mmInStream.read();
mmInStream.read();
//Now, the next byte read should be an "s".
} catch (IOException e) {
return;
}
while (true) {
(...)
一旦实施了这些修复程序，您就可以在接收循环中摆脱
sleep()，因为read()逻辑会阻塞，直到接收到必要的数据为止。另外，除了不满足仅在第一个字节为s的情况下才处理消息的情况，如果不满足该条件，则应关闭连接（因为这表明您的对等方有故障）。注意：我尚未测试此代码，但它应该可以工作。为避免将来出现此类问题，请添加逻辑以验证您的更多假设。例如，在Arduino上，您可以点亮LED
if(strlen(String(Volt))!=4)。如果s不在您期望的位置，请不要忽略该问题；找出原因。