Hi All.
First time asking on the forum, but I have been using many of the pages on here for help.
I am trying to communicate from a computer to an arduino nano over bluetooth for an LEDCube project I have been working on and off for over a year. I have managed to get data sent from the computer to the arduino using an HC-06 module by DSD tech, but I am having reliability issues, resulting in limited effective bandwidth. Data is coming through, it is just really slow, and bluetooth at this speed breaking up this badly does not seem right.
I was using SoftwareSerial, but due to the slowdown, decided to try a mockup board running on the rx/tx pins instead. There is no difference in reliability. Sometimes it works on the 2nd attempt, others it is 30 or 40 tries. Any help would be greatly appreciated. As to one of the questions asked in response to a similar question, no, I do not want to just use a wire. I plan on having this as a display thing, and the power wire is enough, and I don't want to run a wire across my room to connect to it.
Extremely pared down arduino code for bluetooth functionality:
#define baudRate 115200
//vars for BT
char c = ' ';
boolean NL = true;
char BTBuff[32]; //max 32 chars. 2 reserved for carraige return and new line
char BTInput[32];
short BTBuffIndex=0;
void setup() {
// put your setup code here, to run once:
//serial for computer and BT
Serial.begin(baudRate); //Start serial comms
Serial.println("started");
}
void loop() {
//handle bluetooth comms
updateBT();
}
void processBT(){
const char *ptr =strchr(BTBuff,'*');
char *command;
bool checkSumStatus = false;
if(ptr){
int stringSize = ptr-BTBuff;
//get checksum chunks and check
char *str = strtok(BTBuff,"*");
char *checkSumStr = strtok(NULL,"*");
unsigned int sum = atoi(checkSumStr);
unsigned int calcCheckSum = Fletcher16(str,stringSize);
if(sum == calcCheckSum){
Serial.println(sum);
checkSumStatus=true;
}
else{
Serial.println("5");
checkSumStatus=false;
}
}
}
void updateBT(){
// Read from the Bluetooth module and send to the Arduino Serial Monitor
if (Serial.available()>0)
{
c = Serial.read(); //get character
BTBuff[BTBuffIndex]=c; //add to buffer
if(BTBuffIndex>0){
//check last 2 characters, if return, newline then send substring of useable characters through serial. reset index
if(BTBuff[BTBuffIndex-1] == '\r'){
if(BTBuff[BTBuffIndex]=='\n'){
processBT();
BTBuffIndex = -1;// set negative so when added in next line, is at 0;
}
}
}
//every character, increase the active index
BTBuffIndex++;
//if active index too big for content, wrap back to beginning (prevent overwriting memory)
if(BTBuffIndex>=32){
BTBuffIndex=0;
}
}
}
int Fletcher16(char *str,int stringSize){
unsigned int sum1 = 0;
unsigned int sum2 = 0;
for(int i =0;i<stringSize;i++){
sum1 = (sum1 + str[i]) % 255;
sum2 = (sum2 + sum1) % 255;
}
//Serial.print("checksum: ");
//Serial.print(sum1);
//Serial.print(" ");
//Serial.println(sum2);
return (sum1 << 8) | sum2;
}
BluetoothConnector project in JAVA (what I am controlling the cube from). Uses BlueCove maven library
package bluetooth;
//https://stackoverflow.com/questions/33473926/best-practice-java-serial-bluetooth-connection-hc-05
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.bluetooth.DeviceClass;
import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.DiscoveryListener;
import javax.bluetooth.LocalDevice;
import javax.bluetooth.RemoteDevice;
import javax.bluetooth.ServiceRecord;
import javax.bluetooth.UUID;
import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
public class BluetoothConnector {
private static boolean scanFinished = false;
private static boolean connected = false;
private static ArrayList<RemoteDevice> matchedDevices;
private static ArrayList<String> URLs;
private static StreamConnection streamConnection;
private static OutputStream os;
private static InputStreamReader is;
private static JTextArea historyArea= new JTextArea();;
private static String serialMonitorString = "";
private static Scanner s;
//connect calls autoconnect if it can, otherwise starts manual
public static void connect(String filter) {
if(!trySavedConnection()) {
setupWindow(filter);
}
}
//closes all connections
public static void disconnect() throws IOException {
try {
//close streams, scanner, and shows disconnected
s.close();
os.close();
is.close();
streamConnection.close();
}catch(NullPointerException e) {
}
connected = false;
}
//returns connected variable
public static boolean connected() {
return connected;
}
//write string to bluetooth
public static void write(String text) throws IOException {
if(!connected) {
return;
}
//uses carriage return and newline to end strings
String preppedText = text+"\r\n";
updateHistoryAreaText(" > "+preppedText);
os.write(preppedText.getBytes());
}
public static int reliableWrite(String text) throws IOException{
if(!connected) {
return -1;
}
//uses carriage return and newline to end strings
int checksum = Fletcher16(text);
String preppedText = text+"*"+checksum+"\r\n";
updateHistoryAreaText(" > "+preppedText);
int fails = -1;
String result = "";
while(!result.equals(Integer.toString(checksum))) {
os.write(preppedText.getBytes());
result = read();
if(result.equals("")) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
return fails;
}
//read string from bluetooth
public static String read() throws IOException {
String result = "";
if(!connected) {
return "";
}
//if result has content, get it.
char[] charBuffer = new char[255];
int charsRead=-1;
if(is.ready()) {
charsRead=is.read(charBuffer);
}
if(charsRead!=-1) {
for(int i=0;i<charBuffer.length;i++) {
if(i>1) {
if(charBuffer[i]=='\n' && charBuffer[i-1]=='\r') {
break;
}
}
result +=charBuffer[i];
}
}
if(!result.equals("")) {
updateHistoryAreaText(result+"\n");
}
result=result.strip();
return result;
}
//launch serial monitor
public static void serialMonitor() {
if(!connected) {
System.out.println("Not connected");
return;
}
JDialog serialMonitor = new JDialog();
serialMonitor.setTitle("SerialMonitor");
//serialMonitor.setModal(true);
serialMonitor.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
serialMonitor.setSize(750, 400);
//history area shows serial comms
historyArea = new JTextArea();
historyArea.setText(serialMonitorString);
historyArea.setSize(600,300);
historyArea.setLineWrap(true);
historyArea.setEditable(false);
historyArea.setVisible(true);
historyArea.setFont(new Font(Font.MONOSPACED,Font.PLAIN,12));
//put historyArea in scroll
JScrollPane historyScroll = new JScrollPane(historyArea);
historyScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
historyScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
JTextField output = new JTextField();
output.addActionListener(new ActionListener() {
//actionListener listens for enter by default. Try to write and wipe the text
@Override
public void actionPerformed(ActionEvent e) {
String text = output.getText();
output.setText("");
try {
write(text);
} catch (IOException e1) {
e1.printStackTrace();
}
}
});
GridLayout layout = new GridLayout(0,1);
serialMonitor.setLayout(layout);
serialMonitor.add(historyScroll);
serialMonitor.add(output);
serialMonitor.pack();
serialMonitor.setVisible(true);
//make listener and have both sender and listener always save to here somehow
}
//attempts to connect to url.txt
private static boolean trySavedConnection() {
Scanner URLGetter;
try {
//get saves url
File file = new File("url.txt");
URLGetter = new Scanner(file);
String URL = "";
while(URLGetter.hasNextLine()){
URL = URLGetter.nextLine();
}
URLGetter.close();
//connect using url if not empty
if(!URL.equals("")) {
tryConnect(URL);
if(connected) {
return true;
}
else {
return false;
}
}
else {
System.out.println("No saved connection");
return false;
}
} catch (FileNotFoundException e) {
System.out.println("url.txt does not exist");
return false;
}
}
//launches full setup window and establishes connection
private static void setupWindow(String filter) {
JDialog setupDialog = new JDialog();
setupDialog.setTitle("Bluetooth Selector");
//forces program to stall when this is launched
setupDialog.setModal(true);
setupDialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
DefaultListModel<String> scanListModel = new DefaultListModel<String>();
DefaultListModel<String> scanServiceListModel = new DefaultListModel<String>();
JList<String> scanList = new JList<String>(scanListModel);
scanList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
scanList.setLayoutOrientation(JList.VERTICAL);
scanList.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent evt) {
@SuppressWarnings("unchecked")
JList<String> clickedList = (JList<String>)evt.getSource();
//get element clicked on, and run service scan on it.
if (evt.getClickCount() == 2) {
// Double-click detected
int index = clickedList.locationToIndex(evt.getPoint());
try {
serviceScan(matchedDevices.get(index));
scanServiceListModel.removeAllElements();
//service scan populates URLs
if(URLs.size()>0) {
for(int i=0;i<URLs.size();i++) {
scanServiceListModel.addElement(URLs.get(i));
}
}
else {
System.out.println("no Services available, check for unclosed connections or restart");
}
} catch (Exception ex) {
// TODO Auto-generated catch block
Logger.getLogger(BluetoothConnector.class.getName()).log(Level.SEVERE,null,ex);
}
}
}
});
scanList.setVisibleRowCount(5);
JScrollPane scanListScrollPane = new JScrollPane(scanList);
//button to initialize scan for RGBCube
JButton scanButton = new JButton("Scan");
scanButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
try{
scan(filter);
//scan populates matchedDevices. Add to list all devices
scanListModel.removeAllElements();
for(int i=0;i<matchedDevices.size();i++) {
scanListModel.addElement(matchedDevices.get(i).getFriendlyName(false) + ":" + matchedDevices.get(i).getBluetoothAddress());
}
}catch(Exception ex) {
Logger.getLogger(BluetoothConnector.class.getName()).log(Level.SEVERE,null,ex);
}
}
});
JList<String> scanServiceList = new JList<String>(scanServiceListModel);
scanServiceList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
scanServiceList.setLayoutOrientation(JList.VERTICAL);
scanServiceList.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent evt) {
//get service clicked on
@SuppressWarnings("unchecked")
JList<String> clickedServiceList = (JList<String>)evt.getSource();
if (evt.getClickCount() == 2) {
// Double-click detected
int index = clickedServiceList.locationToIndex(evt.getPoint());
try {
String URL = URLs.get(index);
//try to connect to url clicked on
tryConnect(URL);
if(connected) {
//if connected, wipe serial monitor string, save url to file, close dialog
serialMonitorString="";
System.out.println("Connected");
File oldFile = new File("url.txt");
oldFile.delete();
File file = new File("url.txt");
FileWriter f = new FileWriter(file,false);
f.write(URL);
f.close();
setupDialog.dispose();
}
else {
}
} catch (Exception ex) {
// TODO Auto-generated catch block
Logger.getLogger(BluetoothConnector.class.getName()).log(Level.SEVERE,null,ex);
}
}
}
});
scanServiceList.setVisibleRowCount(5);
JScrollPane scanServiceListScrollPane = new JScrollPane(scanServiceList);
setupDialog.setLayout(new FlowLayout());
setupDialog.add(scanButton);
setupDialog.add(scanListScrollPane);
setupDialog.add(scanServiceListScrollPane);
setupDialog.pack();
setupDialog.setVisible(true);
}
//scan for bluetooth devices
private static void scan(String nameFilter) throws Exception{
scanFinished = false;
matchedDevices = new ArrayList<RemoteDevice>();
LocalDevice.getLocalDevice().getDiscoveryAgent().startInquiry(DiscoveryAgent.GIAC, new DiscoveryListener() {
@Override
public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {
try {
//if device found, get name, and add to list of devices
String name = btDevice.getFriendlyName(false);
System.out.format("Pre filter: %s (%s)\n", name, btDevice.getBluetoothAddress());
if(nameFilter.equals("")) {
matchedDevices.add(btDevice);
}
else if(name.matches(nameFilter)) {
matchedDevices.add(btDevice);
}
}catch(IOException e) {
e.printStackTrace();
}
}
@Override
public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {}
@Override
public void serviceSearchCompleted(int transID, int respCode) {}
@Override
public void inquiryCompleted(int discType) {
scanFinished = true;
}
});
while(!scanFinished) {
Thread.sleep(500);
}
}
//scan for bluetooth services
private static void serviceScan(RemoteDevice hc06Device) throws Exception {
URLs = new ArrayList<String>();
UUID uuid = new UUID(0x1101);
UUID[] searchUUIDSet = new UUID[] {uuid};
int[] attrIDs = new int[] {
0x0100
};
scanFinished = false;
//scan for services
LocalDevice.getLocalDevice().getDiscoveryAgent().searchServices(attrIDs, searchUUIDSet,
hc06Device, new DiscoveryListener() {
@Override
public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {
}
@Override
public void inquiryCompleted(int discType) {
}
@Override
public void serviceSearchCompleted(int transID, int respCode) {
scanFinished = true;
}
@Override
public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
//if service found, get url and save it
System.out.println("Scanning record ");
for (int i = 0; i < servRecord.length; i++) {
String URL = servRecord[i].getConnectionURL(ServiceRecord.NOAUTHENTICATE_NOENCRYPT, false);
if (URL != null) {
URLs.add(URL);
break; //take the first one
}
}
}
});
while (!scanFinished) {
Thread.sleep(500);
}
}
//attempts connection to url
private static void tryConnect(String URL) {
System.out.println("URL "+URL);
//address btspp://0014030559FA:1;authenticate=false;encrypt=false;master=false
//if you know your hc05Url this is all you need:
try {
//open connection, setup IO lines
streamConnection = (StreamConnection) Connector.open(URL);
os = streamConnection.openOutputStream();
InputStream stream = streamConnection.openInputStream();
is = new InputStreamReader(stream);
//is = streamConnection.openInputStream();
connected = true;
} catch (IOException e) {
e.printStackTrace();
}
}
//updates text area of serial monitor
private static void updateHistoryAreaText(String string) {
if(string.equals("")) {
serialMonitorString = "";
}
else{
serialMonitorString += string;
}
historyArea.setText(serialMonitorString);
historyArea.setCaretPosition(historyArea.getDocument().getLength());
}
//from https://en.wikipedia.org/wiki/Fletcher%27s_checksum
private static int Fletcher16(String message) {
int sum1 = 0;
int sum2 = 0;
for(int i=0;i<message.length();i++) {
sum1 = (sum1 + message.charAt(i)) %255;
sum2 = (sum2+sum1) %255;
}
//System.out.println("Checksum = " +sum1+ " "+sum2);
//System.out.println("shift combine = " + ((sum1<<8)|sum2));
return (sum1<<8)|sum2;
}
}
Main Java class to send data to arduino
package bluetooth;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
BluetoothConnector.connect(""); //blocking
System.out.println("hello world");
BluetoothConnector.serialMonitor(); //nonblocking, shows serial monitor, send and receive
if(BluetoothConnector.connected()) {
for(int i = 0;i<64;i++) {
int fails = BluetoothConnector.reliableWrite("i:"+i);
if(fails!=-1) {
System.out.println("fails: "+fails);
}
}
}
BluetoothConnector.disconnect(); //must disconnect on close to prevent hanging
}
}
Thank you for making it this far. Please let me know if you need any more info.
