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POMultiple NFC ACR122U devices on a Raspberry Pi using smartcardio in Java
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  1. POMultiple NFC ACR122U devices on a Raspberry Pi using smartcardio in Java
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    copied!<p>I have 3 ACR122U NFC readers connected to a Raspberry Pi. I have a Java program that uses javax.smartcardio to interface with the readers. My program creates threads for each reader found:</p> <pre><code>List&lt;CardTerminal&gt; terminals = TerminalFactory.getDefault().terminals().list(); int terminalCount = terminals.size(); System.out.println("Detected " + String.valueOf(terminalCount) + " terminal/s"); for(int i = 0; i &lt; terminalCount; i++) { System.out.println("Initiating thread :" + String.valueOf(i)); new Thread(new AccessTerminal(i,terminals.get(i))).start(); } </code></pre> <p>Each thread class runs an AccessTerminal class which does basically the following:</p> <pre><code>System.out.println("Thread started... Waiting for card..."); cardTerminal.waitForCardPresent(0); System.out.println("Card found"); card = cardTerminal.connect("*"); cardChannel = card.getBasicChannel(); if(authenticate()) { int UID = getUID(); System.out.println("User identified as :" + String.valueOf(UID)); } cardTerminal.waitForCardAbsent(0); </code></pre> <p>The above code runs perfectly if only 1 ACR122U is connected. It ALSO runs perfectly when I have 3 ACR122U connected to a WINDOWS machine. However if I have two or more connected to a raspberry pi, The one reader does nothing at first but if I first scan the other reader then it gets halfway to "Card found" then freezes, then I can swipe the other reader and it comes up with with a NoCardPresent Exception. Bellow is the errors.</p> <pre><code>Starting system... Detected 2 terminal/s Initiating thread :0 Initiating thread :1 Thread started... Waiting for card... Thread started... Waiting for card... Card found Card found Card not valid Nov 27, 2013 1:02:01 PM livaccess.AccessTerminal run SEVERE: null javax.smartcardio.CardNotPresentException: No card present at sun.security.smartcardio.TerminalImpl.connect(TerminalImpl.java:82) at livaccess.AccessTerminal.run(AccessTerminal.java:41) at java.lang.Thread.run(Thread.java:722) Caused by: sun.security.smartcardio.PCSCException: SCARD_W_REMOVED_CARD at sun.security.smartcardio.PCSC.SCardStatus(Native Method) at sun.security.smartcardio.CardImpl.&lt;init&gt;(CardImpl.java:85) at sun.security.smartcardio.TerminalImpl.connect(TerminalImpl.java:78) ... 2 more </code></pre> <p>If I do exactly the same program with the same setup on a windows machine I get the following output:</p> <pre><code>Starting system... Detected 2 terminal/s Initiating thread :0 Initiating thread :1 Thread started... Waiting for card... Thread started... Waiting for card... Card found Card is valid User identified as :1534 Thread started... Waiting for card... Card found Card is valid User identified as :1534 </code></pre> <p>In both cases I swiped the same card at both readers. Don't worry about the Card is invalid or valid, that is an irrelevant check in my code.</p> <p>If someone has a solution for me I would be very great full. I have a feeling it has to do with linux not differentiating between the two usb devices.</p> <p>Thanks for reading! </p>
 

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