I’m pretty new to Arduino and Processing and and this is also my first time asking a question about coding on the internet.
I’m currently trying to do the following thing for a school project: I want to send a String with data from sensors on my Arduino to a android phone or tablet over bluetooth.
For simplicity’s sake I reduced the code in complexity, removing every part of my code that isn’t trying to facilitate the transfer of a String from Arduino to Processing on Android. The following code is simply trying to send the String “S01E” to the processing app on my phone, saving the String into my “String info” and displaying that string in form of a text(info, 20, 110); element.
Additional Info:
Arduino bluetooth module is a “Bluefruit EZ-Ling BLuetooth Shield”.
Phone is Samsung Galaxy S8.
Processing App is generated with Android mode of Processing.
My phone is successfully paired with the arduino over bluetooth.
The code compiles successfully, but it only shows my text(“test text”, 20, 120); on my phone, but not my text(info, 20, 110);, which I assume means that the String is not being received and the info String stays empty.
How can i proceed from here? Are there some obvious problems in my code. And how can I properly debug my code with the weird stack of technologies that I use?
Processing Code:
import netP5.*;
import android.content.Intent;
import android.os.Bundle;
import ketai.net.bluetooth.*;
import ketai.ui.*;
import ketai.net.*;
KetaiBluetooth bt;
boolean isConfiguring = true;
String info = "";
KetaiList klist;
ArrayList devicesDiscovered = new ArrayList();
// States of the two sensors
int B1in = 0;
int B2in = 0;
//********************************************************************
// The following code is required to enable bluetooth at startup.
//********************************************************************
void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
bt = new KetaiBluetooth(this);
}
void onActivityResult(int requestCode, int resultCode, Intent data) {
bt.onActivityResult(requestCode, resultCode, data);
}
void setup() {
size(displayWidth, displayHeight);
frameRate(10);
orientation(PORTRAIT);
background(255);
stroke(160);
fill(50);
//start listening for BT connections
bt.start();
//at app start select device…
isConfiguring = true;
}
void draw() {
background(255);
text(info,20,110);
text("test text",20,120);
println(info);
}
void onKetaiListSelection(KetaiList klist)
{
String selection = klist.getSelection();
bt.connectToDeviceByName(selection);
//dispose of list for now
klist = null;
}
//Call back method to manage data received
void onBluetoothDataEvent(String who, byte[] data) {
if (isConfiguring)
return;
//received
info = new String(data);
}
And here is my Arduino code:
#include <SoftwareSerial.h>
SoftwareSerial bt(2,3); // RX, TX
// Enthält den String, der an den PC geschickt wird
String data = "S01E";
// Serielle Schnittstelle einrichten, pinModes setzen
void setup() {
bt.begin(9600);
Serial.begin(9600);
}
void loop() {
Serial.println(data);
}
I also asked the same Question on discourse.processing.org. The link to my Question:
https://discourse.processing.org/t/sending-string-from-arduino-to-processing-app-on-android-over-bluetooth/6106
Could you try this?
void setup() {
isConfiguring = true;
size(displayWidth, displayHeight);
frameRate(10);
orientation(PORTRAIT);
background(255);
stroke(160);
fill(50);
//start listening for BT connections
bt.start();
//at app start select device…
isConfiguring = false;
}
It seems the function your using to retrieve data from the Bluetooth event is simply returning because of your Boolean flag is never changing from true.
Related
I want to send some data (int) to android app, I can do it by writing text in Serial, but I need to send int from code. All I get is "?". I'm not sure what type of data SerialBT.write should I use.
Here is my code:
void setup() {
Serial.begin(115200);
SerialBT.begin("ESP32test"); //Bluetooth device name
Serial.println("The device started, now you can pair it with bluetooth!");
}
void loop() {
RawValue = analogRead(15);
Voltage = (RawValue / 4096.0) * 3300; // Gets you mV
Amps = ((Voltage - ACSoffset) / mVperAmp);
OdczytNap= analogRead(2);
napiecie=OdczytNap*(3300/4096.0);
napiecie=map(OdczytNap,0,1023,0,5);
SerialBT.write(napiecie);
SerialBT.write(Amps);
if (SerialBT.available()) {
Serial.write(SerialBT.read());
}
delay(20);
}
I am uploading the code of both the android-studio as well as the arduino uno.. It seems right but somehow it doesn't work
Android Studio code :
package com.example.chintan.doorlock;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import android.os.Handler;
public class MainActivity extends AppCompatActivity {
private final String DEVICE_ADDRESS = "00:21:13:01:ED:10"; //MAC Address of Bluetooth Module
private final UUID PORT_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
private BluetoothDevice device;
private BluetoothSocket socket;
private OutputStream outputStream;
private InputStream inputStream;
Thread thread;
byte buffer[];
boolean stopThread;
boolean connected = false;
String command;
Button lock_state_btn, bluetooth_connect_btn;
TextView lock_state_text;
ImageView lock_state_img;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lock_state_btn = (Button) findViewById(R.id.lock_state_btn);
bluetooth_connect_btn = (Button) findViewById(R.id.bluetooth_connect_btn);
lock_state_text = (TextView) findViewById(R.id.lock_state_text);
lock_state_img = (ImageView) findViewById(R.id.lock_state_img);
bluetooth_connect_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v){
if(BTinit()) //initialises bluetooth
{
BTconnect(); //connects android code to arduino
beginListenForData();
// The code below sends the number 3 to the Arduino asking it to send the current state of the door lock so the lock state icon can be updated accordingly
command = "3";
try
{
outputStream.write(command.getBytes());
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
});
lock_state_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v){
if(connected == false)
{
Toast.makeText(getApplicationContext(), "Please establish a connection with the bluetooth servo door lock first", Toast.LENGTH_SHORT).show();
}
else
{
command = "1";
try
{
outputStream.write(command.getBytes()); // Sends the number 1 to the Arduino. For a detailed look at how the resulting command is handled, please see the Arduino Source Code
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
});
}
void beginListenForData() // begins listening for any incoming data from the Arduino
{
final Handler handler = new Handler();
stopThread = false;
buffer = new byte[1024];
Thread thread = new Thread(new Runnable()
{
public void run()
{
while(!Thread.currentThread().isInterrupted() && !stopThread)
{
try
{
int byteCount = inputStream.available();
if(byteCount > 0)
{
byte[] rawBytes = new byte[byteCount];
inputStream.read(rawBytes);
final String string = new String(rawBytes, "UTF-8");
handler.post(new Runnable()
{
public void run()
{
if(string.equals("3"))
{
lock_state_text.setText("Lock State: LOCKED"); // Changes the lock state text
lock_state_img.setImageResource(R.drawable.locked_icon); //Changes the lock state icon
}
else if(string.equals("4"))
{
lock_state_text.setText("Lock State: UNLOCKED");
lock_state_img.setImageResource(R.drawable.unlocked_icon);
}
}
});
}
}
catch (IOException ex)
{
stopThread = true;
}
}
}
});
thread.start();
}
#Override
protected void onStart()
{
super.onStart();
}
}
And this is my arduino source code :
//Android-controlled Arduino Bluetooth Servo Door Lock by uscv
#include <Servo.h>
#include <EEPROM.h>
Servo servo;
char state;
void setup() {
// put your setup code here, to run once:
servo.attach(7);
if(EEPROM.read(0) == 1) // Reads the EEPROM value stored to know what state the door lock was in before it was last turned off
{ // An EEPROM value of 1 means UNLOCKED and a value of 2 means LOCKED
servo.write(0); // Rotates the servo to the unlocked position
delay(200);
}
else if(EEPROM.read(0) == 2)
{
servo.write(75); // Rotates the servo to the locked position
delay(200);
}
Serial.begin(9600);
}
void loop() {
// put your main code here, to run repeatedly:
if(Serial.available() > 0)
{
char data;
data = Serial.read(); // The variable data is used to store the value sent by the Android app
switch(data)
{
case '1':
if(EEPROM.read(0) == 1) //An EEPROM value of 1 means it is currently unlocked
{
EEPROM.write(0, 2); // Writes the number 2 to address 0 on the Arduino's EEPROM. This value will be used by the Arduino to remember the last state the door lock was in
Serial.print("3"); // Sends the number 3 to the Android app. To see what this does, please see the Android Studio Project file
servo.write(75);
delay(15);
}
else if(EEPROM.read(0) == 2) //An EEPROM value of 2 means it i currently locked
{
EEPROM.write(0, 1); // Writes the number 1 to address 0 on the Arduino's EEPROM. This value will be used by the Arduino to remember the last state the door lock was in
Serial.print("4"); // Sends the number 4 to the Android app. The number sent will be used by the app to update the locked/unlocked icon
servo.write(0);
delay(15);
}
break;
case '3':
if(EEPROM.read(0) == '1')
{
Serial.print("4");
}
else if(EEPROM.read(0) == '2')
{
Serial.print("3");
}
break;
}
}
}
So, first the android app will start bluetooth, then connect to the arduino uno card and then perform the following functions:
1. "3" sent from android phone to arduino
2. received either "4" or "3" based on its status from arduino uno to android
3. Change the lock image on the android phone
4. send "1" from the android phone to the arduino
5. Change the status of the servo motor sg90 from its current position
Now, my android application is error-free and connects to the arduino uno and also is able to start the bluetooth of the phone. It establishes the connection but does not change the position of the servo motor sg90. I dont understand the problem what should we do?
You are calling EEPROM.read() before initializating the EEPROM. In other words for example in your setup() you are checking whether you EEPROM address 0 contains a certain value rather than initialization it with a certain value. Then
in your loop(), again you are checking whether EEPROM address contains a certain value before any value is written to the EEPROM and thus you will never reach the EEPROM write part because your if statements always returns false. So, start first by writing a value to EEPROM address 0.
I am working on an Android app that will constantly receive data from an Arduino HC-05 and store it in a database. For now I am focusing on receiving the data properly (so just displaying it on the screen is my next step).
I have followed this guide (PDF) to setup a basic app that will receive data from the Arduino. However, it doesn't include a section about using the received data. I've tried adding two lines of code to the handleMessage function in order to display the received data on screen, but I don't see any difference in the textview (it stays "Hello World!").
I know that my Arduino is sending the data just fine, since on another app called "Serial Bluetooth Terminal" it is displayed properly. Here is the code for the Handler class:
Handler mHandler = new Handler() {
#Override
public void handleMessage(Message msg) {
byte[] writeBuf = (byte[]) msg.obj;
int begin = (int)msg.arg1;
int end = (int)msg.arg2;
switch(msg.what) {
case 1:
String writeMessage = new String(writeBuf);
writeMessage = writeMessage.substring(begin, end);
// 2 lines of code I've added here:
TextView tempTextView = (TextView) findViewById(R.id.text_view);
tempTextView.setText(writeMessage);
break;
}
}
};
Aside from the 2 lines, the code is basically the same as the final stage of the guide. And here is the code for the Arduino (which currently just sends "1 2.00 3.00" over and over):
#include <SoftwareSerial.h>
SoftwareSerial BTSerial(0, 1); //RX|TX
int Temp= 1;
float Ph = 2;
float Ec = 3;
void setup() {
Serial.begin(9600);
BTSerial.begin(9600);
}
void loop() {
Serial.print(Temp);
Serial.print(" ");
delay(100);
Serial.print(Ph);
Serial.print(" ");
delay(100);
Serial.print(Ec);
Serial.print(" ");
delay(100);
Serial.print('\n');
if(Serial.available())
BTSerial.write(Serial.read());
}
My app uses the foreground dispatch system to allow a user to tap their NFC tag in order to perform a read-then-write operation on the tag.
It works nicely if the user taps their tag properly (i.e., they tap it in the correct place on the phone and leave it connected for long enough), but if they physically remove the tag too early, then ndef.writeNdefMessage(...) throws an IOException.
That means the write operation fails, which is fair enough. But the real problem is that the same failed operation also deletes the entire ndef formatting/message from the tag!
My code is built around the snippets from the Advanced NFC | Android Developers page (as unfortunately the link to the ForegroundDispatch sample appears to be broken and there is no such sample project to import into Android Studio).
Step 1. Here is the logcat/stacktrace output when the user first taps their NFC tag, but moves it away too soon:
03-28 20:15:18.589 21278-21278/com.example.exampleapp E/NfcTestActivity: Tag error
java.io.IOException
at android.nfc.tech.Ndef.writeNdefMessage(Ndef.java:320)
at com.example.exampleapp.NfcTestActivity.onNewIntent(NfcTestActivity.java:170)
at android.app.Instrumentation.callActivityOnNewIntent(Instrumentation.java:1224)
at android.app.ActivityThread.deliverNewIntents(ActivityThread.java:2946)
at android.app.ActivityThread.performNewIntents(ActivityThread.java:2959)
at android.app.ActivityThread.handleNewIntent(ActivityThread.java:2968)
at android.app.ActivityThread.access$1700(ActivityThread.java:181)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1554)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6145)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
03-28 20:15:18.599 1481-17792/? E/SecNfcJni: nfaConnectionCallback: NFA_SELECT_RESULT_EVT error: status = 3
03-28 20:15:18.599 1481-1502/? E/SecNfcJni: reSelect: tag is not active
Step 2. Next, the same user taps the same tag again but it appears to no longer contain an ndef message (which I have confirmed by altering the code and checking that ndef.getCachedNdefMessage() returns null):
03-28 20:15:27.499 21278-21278/com.example.exampleapp E/NfcTestActivity: Tag error
java.lang.Exception: Tag was not ndef formatted: android.nfc.action.TECH_DISCOVERED
at com.example.exampleapp.NfcTestActivity.onNewIntent(NfcTestActivity.java:124)
at android.app.Instrumentation.callActivityOnNewIntent(Instrumentation.java:1224)
at android.app.ActivityThread.deliverNewIntents(ActivityThread.java:2946)
at android.app.ActivityThread.performNewIntents(ActivityThread.java:2959)
at android.app.ActivityThread.handleNewIntent(ActivityThread.java:2968)
at android.app.ActivityThread.access$1700(ActivityThread.java:181)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1554)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6145)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
I am getting this issue with both devices I have tested with so far - a Samsung Galaxy Core Prime (a lower end phone) running Android 5.1.1 and a Samsung Galaxy A5 (a mid range phone) running Android 5.0.2.
The NFC tags used by my app contain important information (i.e., inadvertently deleting the tag data is not an option!), so my questions are...
Why is my code (see below) erasing the tag data like this?
How can I fix the underlying problem, or is there an acceptable workaround?
Would it be worth me trying to use NfcA or IsoDep rather than Ndef?
Having done a lot of searching, I'm very surprised that this problem has not been discussed elsewhere, so if the problem isn't to do with my code, then could it be to do with the NFC tags I am using?...
The tags I'm using are NXP MIFARE Ultralight (Ultralight C) - NTAG203 (Tag type: ISO 14443-3A). Some of these I bought from ebay, and some I bought from Rapid NFC (a reputable company), yet I seem to have this problem with all of them.
Here is my complete code for the activity:
package com.example.exampleapp;
import android.app.PendingIntent;
import android.content.Intent;
import android.content.IntentFilter;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;
public class NfcTestActivity extends AppCompatActivity {
private static String LOG_TAG = NfcTestActivity.class.getSimpleName();
private static int SUCCESS_COUNT = 0;
private static int FAILURE_COUNT = 0;
private NfcAdapter nfcAdapter;
private PendingIntent pendingIntent;
private IntentFilter[] intentFiltersArray;
private String[][] techListsArray;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nfc_test);
getSupportActionBar().setDisplayShowHomeEnabled(true);
nfcAdapter = NfcAdapter.getDefaultAdapter(this);
if (nfcAdapter == null) {
makeToast("NFC not available!", Toast.LENGTH_LONG);
finish();
}
else {
//makeToast("NFC available");
pendingIntent = PendingIntent.getActivity(this, 0, new Intent(this, getClass()).addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP), 0);
IntentFilter ndef = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);
try {
ndef.addDataType("*/*"); /* Handles all MIME based dispatches.
You should specify only the ones that you need. */
} catch (IntentFilter.MalformedMimeTypeException e) {
throw new RuntimeException("fail", e);
}
intentFiltersArray = new IntentFilter[]{
ndef
};
techListsArray = new String[][]{
new String[]{
Ndef.class.getName()
}
};
}
}
#Override
public void onPause() {
super.onPause();
if (nfcAdapter != null) {
nfcAdapter.disableForegroundDispatch(this);
}
}
#Override
public void onResume() {
super.onResume();
if (nfcAdapter != null) {
nfcAdapter.enableForegroundDispatch(this, pendingIntent, intentFiltersArray, techListsArray);
}
}
public void onNewIntent(Intent intent) {
Ndef ndef = null;
try {
String action = intent.getAction();
//makeToast("action: " + action);
if (!NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {
throw new Exception("Tag was not ndef formatted: " + action); // line #124
}
else {
Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
//do something with tagFromIntent
ndef = Ndef.get(tag);
//makeToast("ndef: " + ndef);
if (ndef == null) {
throw new Exception("ndef == null!");
}
else {
// Connect
ndef.connect();
// Get cached message
NdefMessage ndefMessageOld = ndef.getCachedNdefMessage();
if (ndefMessageOld == null) {
throw new Exception("No ndef message on tag!");
}
else {
// Get old records
NdefRecord[] ndefRecordsOld = ndefMessageOld.getRecords();
int numRecords = (ndefRecordsOld == null) ? 0 : ndefRecordsOld.length;
// Create/copy 'new' records
NdefRecord[] ndefRecordsNew = new NdefRecord[numRecords];
for (int i = 0; i < numRecords; i++) {
ndefRecordsNew[i] = ndefRecordsOld[i];
}
// Create new message
NdefMessage ndefMessageNew = new NdefMessage(ndefRecordsNew);
// Write new message
ndef.writeNdefMessage(ndefMessageNew); // line #170
SUCCESS_COUNT++;
// Report success
String msg = "Read & wrote " + numRecords + " records.";
makeToast(msg);
Log.d(LOG_TAG, msg);
}
}
}
}
catch(Exception e) {
FAILURE_COUNT++;
Log.e(LOG_TAG, "Tag error", e);
makeToast("Tag error: " + e, Toast.LENGTH_LONG);
}
finally {
try {
if (ndef != null) {
ndef.close();
}
}
catch(Exception e) {
Log.e(LOG_TAG, "Error closing ndef", e);
makeToast("Error closing ndef: " + e, Toast.LENGTH_LONG);
}
makeToast("Successes: " + SUCCESS_COUNT + ". Failures: " + FAILURE_COUNT);
}
}
private void makeToast(final String msg) {
makeToast(msg, Toast.LENGTH_SHORT);
}
private void makeToast(final String msg, final int duration) {
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
Toast.makeText(NfcTestActivity.this, msg, duration).show();
}
});
}
}
I really wonder what else you would expect to happen when you remove a storage device in the middle of overwriting its data.
Why is my code (see below) erasing the tag data like this?
You code is not really "erasing" data. It simply starts overwriting the data from the beginning of the tag memory leaving the tag in an undefined state when you interrupt writing.
An NFC tag only supports storing one NDEF message at a time. Consequently, when you start to write an new NDEF message, the old NDEF message needs to be overwritten. Thus,
ndef.writeNdefMessage(ndefMessageNew);
will overwrite the existing NDEF message starting at its first block. For NTAG203, MIFARE Ultralight and MIFARE Ultralight C (that's three different tag types by the way), this first block will be around block 4. writeNdefMessage will then write the new message block for block replacing old data with new data.
If the write procedure is interrupted (e.g. by pulling the tag from the reader field), then only parts of the new message are written (and parts of the old message may remain on the tag). Since neither the old nor the new message are complete, Android (just as any other NDEF reader) cannot read a valid NDEF message from the tag and, therefore, does not detect any NDEF message. The tag is still detected by your app since you also registered for the TECH_DISCOVERED intent (which does not require the tag to contain a vaild NDEF message).
How can I fix the underlying problem, or is there an acceptable workaround?
If your NDEF message is that long that your users are actually able to pull the tag while writing there is not much you can do against the pulling itself (except for instructing the users not to do so). NFC tags also do not have any form of pulling protection out-of-the-box. I.e. there are currently no tags that will reliably store the old NDEF message until the new NDEF message was written completely.
What you could possibly do is to store the old (or the new) NDEF message (possibly mapped to the tag ID) within your app and let the users restart the write procedure once it failed. Still, that would require user cooperation.
Would it be worth me trying to use NfcA or IsoDep rather than Ndef?
That might be another option: Don't use NDEF for the critical data but use an application-specific memory layout instead (or in addition to NDEF). NTAG/MIFARE Ultralight have a command set on top of ISO 14443-3A (NFC-A) and do not support ISO-DEP (ISO 14443-4). Thus, you could use NfcA (or MifareUltralight) to directly read from/write to the tags using low-level commands. You could structure the tag memory in two sections that you use to store the old and the new data:
Block x: Flag indicating which section (1 or 2) contains the valid data
Block x+1: First block of section 1
Block x+2: Second block of section 1
[...]
Block x+m: Last block of section 1
Block x+m+1: First block of section 2
Block x+m+2: Second block of section 2
[...]
Block x+2*m: Last block of section 2
Where x is the first block of your custom memory structure (you could even start that area after some fixed NDEF message) and m is the length of each section in blocks (1 block on NTAG/MF Ultralight has 4 bytes).
You would then use something like this to read and update your tag:
Read from block x to find out which section contains the vaild (newest) data -> section s.
Read the data from section s and use it as current data.
Write the new data to the other section (if s = 1: section 0; if s = 0: section 1).
If the data was written successfully (and completely), update block x with the new section number.
Low-level read and write commands look like this:
READ:
byte[] result = nfcA.transceive(new byte[] {
(byte)0x30, // READ
(byte)(blockNumber & 0x0ff)
});
WRITE:
byte[] result = nfcA.transceive(new byte[] {
(byte)0xA2, // WRITE
(byte)(blockNumber & 0x0ff),
byte0, byte1, byte2, byte3
});
I'm wondering if anybody can help me figure out what is causing the data I am sending to become corrupt.
My setup is currently an Arduino pro mini with a HM-10 bluetooth module connected (I have also tried HM-11 Module too) and an Android application to receive the bluetooth data.
Module setup: http://letsmakerobots.com/node/38009
If I send data with big enough intervals then the data is fine, but if I send the data continuously I see messages getting mixed up and lost. To test this I send "$0.1,0.2,0.3,0.4,0.5" to the Android application from the Arduino, sometimes the stream of data appears to send fine but other times it is really quite scrambled. Please see the below graphs that demonstrate this:
Good case:
Bad case:
Arduino code:
String inputString = ""; //Hold the incoming data.
boolean stringComplete = false; //Determines if the string is complete.
boolean realtime = false;
void setup()
{
Serial.begin(9600);
delay(500);
Serial.print("AT+START");
delay(500);
}
void loop()
{
if(stringComplete)
{
if(inputString.equals("rStart"))
{
Serial.println("$startACK");
realtime = true;
}
else if(inputString.equals("stop"))
{
Serial.println("$stopACK");
realtime = false;
}
else{
Serial.print(inputString);
}
inputString = "";
stringComplete = false;
}
if(realtime)
{
Serial.println("$0.1,0.2,0.3,0.4,0.5,0.6");
delay(10);
}
}
void serialEvent() {
while (Serial.available())
{
// get the new byte:
char inChar = (char)Serial.read();
if (inChar == '\n')
{
stringComplete = true;
}
else
{
inputString += inChar;
}
}
}
The Android side just receives the data and then parses it in an IntentService:
#Override
protected void onHandleIntent(Intent intent) {
//Incoming command.
String rawData = intent.getStringExtra(DataProcessingIntentService.REQUEST);
//Append our new data to our data helper.
Log.i(this.getClass().getName(), "Previous Raw: (" + DataProcessingHelper.getInstance().getData() + ")");
DataProcessingHelper.getInstance().appendData(rawData);
Log.i(this.getClass().getName(), "New Raw: (" + DataProcessingHelper.getInstance().getData() + ")");
commandStartIndex = DataProcessingHelper.getInstance().getData().indexOf("$");
commandEndIndex = DataProcessingHelper.getInstance().getData().indexOf("\n");
//Set this as the data starting point.
if(commandStartIndex != -1){
DataProcessingHelper.getInstance().offsetData(commandStartIndex);
}
//Ensure that a command has been found and that the end index is after the starting index.
if(commandStartIndex != -1 && commandEndIndex > commandStartIndex){
//Remove the command structure from the command.
command = DataProcessingHelper.getInstance().getData().substring(commandStartIndex+1, commandEndIndex-1); //Remove the \r\n end command.
DataProcessingHelper.getInstance().offsetData(commandEndIndex+1);
if(command.length() > 1){
//Split the data out of the comand.
splitData = command.split(",");
Log.i(this.getClass().getName(), "Broadcasting the processed data. (" + command + ")");
//Broadcast data.
Intent broadcastIntent = new Intent();
broadcastIntent.setAction(DataProcessingIntentService.RESPONSE);
broadcastIntent.addCategory(Intent.CATEGORY_DEFAULT);
broadcastIntent.putExtra(DataProcessingIntentService.RESPONSE, splitData);
sendBroadcast(broadcastIntent);
}else{
Log.e(this.getClass().getName(), "Command is less than 1 character long!");
}
}
}
Thank you for any help!
I have now figured out what was causing this problem. It appears that BLE only supports a maximum of 20 bytes per a transaction. The time between these transactions is different depending on what you are using. I'm currently using notifications which means that I can send 20 bytes every 7.5 milliseconds maximum. I have opted for 10 milliseconds to be safe. I will now need to look into breaking up packets into 20 bytes maximum to ensure no data corruption.