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--- tutorials:products:rfidnfc:faqs.html [2012/07/23 18:13]
ktownsend [Can I set a delay calling readPassiveTargetID() ?]
+++ tutorials:products:rfidnfc:faqs.html [2016/01/28 18:05]
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-====== Frequently Asked Questions  ======
-Blah blah blah
-===== Can I set a delay calling readPassiveTargetID() ?  =====
-readPassiveTargetID() intentionally waits around in a blocking delay until a card enters the magnetic field.  The reason for this blocking delay is to ensure a well-understood command/response flow.  Once the magnetic field is activated and a read request is sent via readPassiveTargetID, you can keep sending new commands to the PN532, but the moment a card or tag enters the field, the PN532 will send a response to the initial read request, even if it's in the middle of some other response or activity.  To avoid having to debug this in SW, a blocking delay was implemented to keep the command/response pattern as clear as possible.
-As a workaround to this blocking-delay limitation, an optional programmable delay was recently added to the NFC libraries to allow you to set a specific timeout after read requests.  By default, the PN532 will wait forever for a card to enter the field, but specifying an optional 8-bit timeout delay will cause the read request to be aborted after the specified delay, and you can safely send new commands without worrying about mixing up response frames.
-Example Code:
-ToDo

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