Develop Reference

Why when reading NFCtag with Android phone you get different tag ID then when reading with dedicated reader?

I am using an Android Cilico F750 and the dedicated RFID reader is CF-RS103.
The RFID tag type is MIFARE Ultralight type C.
When read with a dedicated card reader the id of tag is: 2054270212(10 digit).
But when read with Android phone the id is: 36139312876727556(17digit) and reversed id is: 1316602805183616 (16digit).
Does anyone know why this happens and if its possible to convert the 10digit id to 17digit id or vice versa.
I use intents to detect tag and to resolve intent I use this:
public void resolveIntent(Intent intent){
String action = intent.getAction();
if(NfcAdapter.ACTION_TAG_DISCOVERED.equals(action)
||NfcAdapter.ACTION_TECH_DISCOVERED.equals(action)
||NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action))
{
Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);
NdefMessage[] msgs;
if(rawMsgs!=null)
{
msgs= new NdefMessage[rawMsgs.length];
for(int i=0; i<rawMsgs.length; i++)
{
msgs[i]=(NdefMessage) rawMsgs[i];
}
}
else
{
byte[] empty = new byte[0];
byte[] id = intent.getByteArrayExtra(NfcAdapter.EXTRA_ID);
Tag tag = (Tag) intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
byte[] payload = dumpTagData(tag).getBytes();
NdefRecord record = new NdefRecord(NdefRecord.TNF_UNKNOWN,empty,id,payload);
NdefMessage msg = new NdefMessage(new NdefRecord[]{record});
msgs= new NdefMessage[] {msg};
}
displayMsgs(msgs);
}}
And this are my helper functions:
private void displayMsgs(NdefMessage[] msgs)
{
if(msgs==null || msgs.length==0) {
return;
}
StringBuilder builder = new StringBuilder();
List<ParsedNdefRecord> records= NdefMessageParser.parse(msgs[0]);
final int size = records.size();
for(int i=0;i<size;i++)
{
ParsedNdefRecord record = records.get(i);
String str = record.str();
builder.append(str).append("\n");
}
text.setText(builder.toString());
}
private String dumpTagData(Tag tag) {
StringBuilder sb = new StringBuilder();
byte[] id = tag.getId();
sb.append("ID (hex): ").append(toHex(id)).append('\n');
sb.append("ID (reversed hex):").append(toReversedHex(id)).append('\n');
sb.append("ID (dec): ").append(toDec(id)).append('\n');
sb.append("ID (reversed dec):").append(toReversedDec(id)).append('\n');
String prefix = "android.nfc.tech.";
sb.append("Technologies: ");
for (String tech: tag.getTechList()) {
sb.append(tech.substring(prefix.length()));
sb.append(", ");
}
sb.delete(sb.length() - 2, sb.length());
for (String tech: tag.getTechList()) {
if (tech.equals(MifareClassic.class.getName())) {
sb.append('\n');
String type = "Unknown";
try {
MifareClassic mifareTag = MifareClassic.get(tag);
switch (mifareTag.getType()) {
case MifareClassic.TYPE_CLASSIC:
type = "Classic";
break;
case MifareClassic.TYPE_PLUS:
type = "Plus";
break;
case MifareClassic.TYPE_PRO:
type = "Pro";
break;
}
sb.append("Mifare Classic type: ");
sb.append(type);
sb.append('\n');
sb.append("Mifare size: ");
sb.append(mifareTag.getSize() + " bytes");
sb.append('\n');
sb.append("Mifare sectors: ");
sb.append(mifareTag.getSectorCount());
sb.append('\n');
sb.append("Mifare blocks: ");
sb.append(mifareTag.getBlockCount());
} catch (Exception e) {
sb.append("Mifare classic error: " + e.getMessage());
}
}
if (tech.equals(MifareUltralight.class.getName())) {
sb.append('\n');
MifareUltralight mifareUlTag = MifareUltralight.get(tag);
String type = "Unknown";
switch (mifareUlTag.getType()) {
case MifareUltralight.TYPE_ULTRALIGHT:
type = "Ultralight";
break;
case MifareUltralight.TYPE_ULTRALIGHT_C:
type = "Ultralight C";
break;
}
sb.append("Mifare Ultralight type: ");
sb.append(type);
}
}
return sb.toString();
}
private String toHex(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (int i = bytes.length - 1; i >= 0; --i) {
int b = bytes[i] & 0xff;
if (b < 0x10)
sb.append('0');
sb.append(Integer.toHexString(b));
if (i > 0) {
sb.append(" ");
}
}
return sb.toString();
}
private String toReversedHex(byte[] bytes) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < bytes.length; ++i) {
if (i > 0) {
sb.append(" ");
}
int b = bytes[i] & 0xff;
if (b < 0x10)
sb.append('0');
sb.append(Integer.toHexString(b));
}
return sb.toString();
}
private long toDec(byte[] bytes) {
long result = 0;
long factor = 1;
for (int i = 0; i < bytes.length; ++i) {
long value = bytes[i] & 0xffl;
result += value * factor;
factor *= 256l;
}
return result;
}
private long toReversedDec(byte[] bytes) {
long result = 0;
long factor = 1;
for (int i = bytes.length - 1; i >= 0; --i) {
long value = bytes[i] & 0xffl;
result += value * factor;
factor *= 256l;
}
return result;
}`
EDIT: I managed to resolve this issue by truncating the 7-byte HEX ID to 4-bytes.
And then formating the decimal ID if its total lenght is less than 10 digits with this statement that basically adds zeroes from left side if DEC ID is smaller than 10 digits:
String strFinal=String.format("%010d", Long.parseLong(str));
This document that describes how the ID is converted from HEX8 TO DEC10 helped me alot aswell: https://www.batag.com/download/rfidreader/LF/RAD-A200-R00-125kHz.8H10D.EM.V1.1.pdf
And a huge thanks to #Andrew and #Karam for helping me resolve this!

The card reader on the PC is configured wrong, it is configured by default to display the ID as 10 digit decimal number (4 byte) when the card has a 7 byte ID.
It thus has to loose some data, it is doing this by truncating the ID to the first 4 bytes of the 7 byte ID
Use the software on the PC change the output format to something suitable for the ID size on the Mifare Ultralight C cards (8 Hex?)
or
Use Mifare Classic cards instead as these had 4 byte ID
or
truncate the 7 byte ID to 4 bytes e.g. change bytes.length to 4 (a hard coding to the first 4 bytes in the 7 byte ID) in your code and handle the fact that there is a very large number (around 16.7 million) of Mifare Ultralight C cards that will seem to have the same "ID" as you want to display it
This is because the spec's give by a seller on Amazon https://www.amazon.co.uk/Chafon-CF-RS103-Multiple-Support-Compatible-Black/dp/B017VXVZ66 (I cannot find any details on the manufacturer's site)
It says "Default output 10 digit Dec, control output format through software. "
"Support with windows,linux and android system, but can only set output format in windows pcs.No programming and software required, just plug and play. "
The only sensible answer is move everything to use a 7 byte ID.

I don't know why are you trying always to convert to decimal?
and please try to explain more about the code you use to read the UID.
about your numbers and to convert 17 digits to 10 digits; I convert both of them to Hex:
36139312876727556(17digit) in Hex : 8064837A71AD04.
2054270212(10 digit) in Hex: 7A71AD04
as you notice you can just tirm first three bytes to get the 10 digits.
and I do belive the both of them are not the UID. but the 7bytes as sayed Andrew, and you already read it in the your photo : (04:B5:71:7A:83:64:80)

So I think the answer is that because you are converting a 7 byte ID to decimal you are getting variable lengths of numbers because of the conversion to decimal.
"The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive)."
From https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html
Could generate a decimal number with 1,2 or 3 characters thus as decimal the id can vary in length.
It also looks like that conversion is going wrong as in theory it should have negative numbers in there as well.
It is much better to handle it as a hex string if you want it to be human readable.
The correct method in Java to convert the 2 pages of the ID to hex is
StringBuilder Uid;
for (int i = 0; i < result.length; i++) {
// byte 4 is a check byte
if (i == 3) continue;
Uid.append(String.format("%02X ", result[i]));
}
Note as per the spec sheet of the card https://www.nxp.com/docs/en/data-sheet/MF0ICU2_SDS.pdf (Section 7.3.1)
There is check byte that is part of the ID, while this will always be the same on the same card and will still give you a unique ID it is technically not part of the ID.
Or if not reading at a low level then
https://developer.android.com/reference/android/nfc/Tag#getId()
will get you the id.
Note that the "36139312876727556(17digit) and reversed id" when converted to hex and reversed actual is 7 bytes and start with the right number.
The 10 digit just looks like the first 4 bytes of the 7 byte number also reversed.

invalid conversion from 'byte*' to 'byte'

invalid conversion from 'byte*' to 'byte'
i have write this arduino function
byte receiveMessage(AndroidAccessory acc,boolean accstates){
if(accstates){
byte rcvmsg[255];
int len = acc.read(rcvmsg, sizeof(rcvmsg), 1);
if (len > 0) {
if (rcvmsg[0] == COMMAND_TEXT) {
if (rcvmsg[1] == TARGET_DEFAULT){
byte textLength = rcvmsg[2];
int textEndIndex = 3 + textLength;
byte theMessage[textLength];
int i=0;
for(int x = 3; x < textEndIndex; x++) {
theMessage[i]=rcvmsg[x];
i++;
delay(250);
}
return theMessage;
delay(250);
}
}
}
}
}
this is the error
In function byte receiveMessage(AndroidAccessory, boolean) invalid conversion from byte*' to 'byte"
this function is to receive the data from the android and return it as a byte array

You need to use dynamic allocation, or pass the array to the function as a parameter which is a better solution in your case
void receiveMessage(AndroidAccessory acc, boolean accstates, byte *theMessage){
if (theMessage == NULL)
return;
if(accstates){
byte rcvmsg[255];
int len = acc.read(rcvmsg, sizeof(rcvmsg), 1);
if (len > 0) {
if (rcvmsg[0] == COMMAND_TEXT) {
if (rcvmsg[1] == TARGET_DEFAULT){
byte textLength = rcvmsg[2];
int textEndIndex = 3 + textLength;
int i=0;
for(int x = 3; x < textEndIndex; x++) {
theMessage[i]=rcvmsg[x];
i++;
delay(250);
}
return;
}
}
}
}
}
with this, you will call the function passing the array to it, for example
byte theMessage[255];
receiveMessage(acc, accstates, theMessage);
/* here the message already contains the data you read in the function */
But you can't return a local variable, because the data is only valid in the scope where the variable is valid, in fact it's invalid right outside the if (rcvmsg[0] == COMMAND_TEXT) block, because you defined it local to that block.
Note: please read Wimmel's comment, or you could set the last byte to '\0' if it's just text, and then use the array as a string.

As far as the error is concerned you are returning the incorrect value.
theMessage is a byte array not a byte
Also the last answers explains why cant you return local variable pointer

What the value mean convert from string to Hex for BLE?

I am developing BLE in Android.
And I try to send string value to BLE device
It seem the string need to convert to byte before send to BLE device.
I found some code like the following , the code seems can convert the string value to byte.
private byte[] parseHex(String hexString) {
hexString = hexString.replaceAll("\\s", "").toUpperCase();
String filtered = new String();
for(int i = 0; i != hexString.length(); ++i) {
if (hexVal(hexString.charAt(i)) != -1)
filtered += hexString.charAt(i);
}
if (filtered.length() % 2 != 0) {
char last = filtered.charAt(filtered.length() - 1);
filtered = filtered.substring(0, filtered.length() - 1) + '0' + last;
}
return hexStringToByteArray(filtered);
}
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
private int hexVal(char ch) {
return Character.digit(ch, 16);
}
I call the above function before send the string to the BLE device like the following code.
byte[] value = parseHex(text);
mCharacteristic.setValue(value);
mBluetoothGatt.writeCharacteristic(mCharacteristic);
The BLE device will show the value which I have send to it. But the value is strange and I did not under stand what it mean.
The value what I send and the value show from BLE device are like the following.
Send BLE Show
1 1
2 2
9 9
10 16
11 17
20 32
30 48
40 64
70 112
90 144
99 153
100 16
I did not understand what the value mean show on BLE device...
Does someone help me ?

You are sending the hex values, which is a base 16 system, but your BLE Show values are in decimal.
Therefore sending 10 in hex is 1*16+0*1=16 in decimal. Similarly, 99 is 9*16+9*1=153 in decimal

String Multiline - Android

i got this issue and i don't know how to solve it. Here is the problem:
1 - i have a data in my database who i split into a strings[] and then i split this strings[] into another 2 strings[] (even and odd lines). Everything works fine but when i want to join all the lines into a single String i got a multi line string intead of a single line. Someone can help me?
data
abcdef//
123456//
ghijkl//
789012
code:
String text = "";
vec1 = data.split("//"); //split the data
int LE = 0;
for (int a = 0; a < vec1.length; a++) { //verify how many even and odds line the data have
if (a % 2 == 0) { //if 0, LE++
LE++;
}
}
resul1 = new String[LE];
int contA = 0, contB = 0;
for (int c = 0; c < resul1.length; c++) {
if (c % 2 != 0) {
text += " " + resul1[c].toLowerCase().replace("Á","a").replace("Ã","a").replace("ã","a").replace("â","a").replace("á","a").replace("é","e").replace("É","e")
.replace("ê","e").replace("í","i").replace("Í","i").replace("ó","o").replace("Ó","o").replace("õ","o").replace("Õ","o").replace("ô","o").replace("Ô", "o")
.replace("Ú","u").replace("ú","u").replace("ç","c").replace("_","").replace("<","").replace(">","");
contA++;
}
}
And the String looks like
abcdef
ghijkl
instead of
abcdefghijkl

You should use replaceAll() method.
text.replaceAll("\\r\\n|\\r|\\n", ""); // the method removes all newline characters

Android - Strip extra \r\n's in stream?

Updated question: I am trying to connect to a terminal emulator using a library in android, this will connect to a serial device and should show me sent/received data. I should be able to send data over the connection via a text box below the terminal or by typing in the terminal itself and hitting enter on the keyboard in both cases.
When I was sending data via textbox I had to append \n to the data to get to a new line when I pressed the enter key like so:
mEntry = (EditText) findViewById(R.id.term_entry);
mEntry.setOnEditorActionListener(new TextView.OnEditorActionListener() {
#Override
public boolean onEditorAction(TextView v, int actionId,
KeyEvent event) {
/* Ignore enter-key-up events. */
if (event != null && event.getAction() == KeyEvent.ACTION_UP) {
return false;
}
Editable e = (Editable) v.getText();
String data = e.toString() + "\n";
sendOverSerial(data.getBytes());
TextKeyListener.clear(e);
return true;
}
});
And the write method:
public void write(byte[] bytes, int offset, int count) {
super.write(bytes, offset, count);
if (isRunning()) {
doLocalEcho(bytes);
}
return;
}
When I was hitting enter after typing in the terminal session itself no new line was occurring at all. So I had to test the data for \r and replace it with \r\n:
private void doLocalEcho(byte[] data) {
String str = new String(data);
appendToEmulator(data, 0, data.length);
notifyUpdate();
}
public void write(byte[] bytes, int offset, int count) {
// Count the number of CRs
String str = new String(bytes);
int numCRs = 0;
for (int i = offset; i < offset + count; ++i) {
if (bytes[i] == '\r') {
++numCRs;
}
}
if (numCRs == 0) {
// No CRs -- just send data as-is
super.write(bytes, offset, count);
if (isRunning()) {
doLocalEcho(bytes);
}
return;
}
// Convert CRs into CRLFs
byte[] translated = new byte[count + numCRs];
int j = 0;
for (int i = offset; i < offset + count; ++i) {
if (bytes[i] == '\r') {
translated[j++] = '\r';
translated[j++] = '\n';
} else {
translated[j++] = bytes[i];
}
}
super.write(translated, 0, translated.length);
// If server echo is off, echo the entered characters locally
if (isRunning()) {
doLocalEcho(translated);
}
}
So that worked fine, now when I typed in the terminal session itself and hit enter i got the newline I wanted. However now every time I send data from the text box with with \n there was an extra space between every newline as well as getting the extra newline.
http://i.imgur.com/gtdIH.png
So I thought that when counting the number of carriage returns peek ahead at the next byte, and if it is '\n' don't count it:
for (int i = offset; i < offset + count; ++i) {
if (bytes[i] == '\r' &&
(
(i+1 < offset + count) && // next byte isn't out of index
(bytes[i+1] != '\n')
) // next byte isn't a new line
)
{
++numCRs;
}
}
This fixed the problem of the spaces...but that was rather stupid as I am now back in a circle to the original problem, if I type directly in the terminal there is no new line, as it sees the \r\n and sees the next byte is invalid. What would be the best way to get both working together? I either have these weird extra spaces and all input is fine, or normal spacing and I can't enter text directly from the terminal, only the textbox. I assume it's really easy to fix, I just am scratching my head looking at it.

EDIT: Not fixed, thought I had but then when I enter directly from the terminal enter does not produce a new line. It must be because the \n is ignored after the \r
I have most of this fixed. When counting the number of carriage returns peek ahead at the next byte, and if it is '\n' don't count it:
for (int i = offset; i < offset + count; ++i) {
if (bytes[i] == '\r' &&
(
(i+1 < offset + count) && // next byte isn't out of index
(bytes[i+1] != '\n')
) // next byte isn't a new line
)
{
++numCRs;
}
}
The only problem left now is that I still get the prompt back twice like this:
switch#
switch#