ANSI speci?¬?es that a stored Group ID of zero (0) always
results in a match. For P2P commands, both standards require a Tag ID match. However,
ISO requires that the Owner ID must match as well as the Tag ID for P2P commands with
an Owner ID present in both the tag and the command.
Once the packet analysis unit veri?¬?es that the packet requires a response, it sends a
signal to the interrupt process unit to process the packet stored in the FIFO. Because the
packet analysis occurs in parallel with the packet buffering, a signal can be sent to the
interrupt unit before the entire packet is buffered. If the packet does not require processing
it is dropped from the FIFO. This prevents the processor from being powered up unless it is
needed to process the packet.
11.4.2.5 Interrupt Process Unit
The interrupt process unit will wake up the processor only when a whole RFID packet has
been stored into the output FIFO and the analysis result forwarded by the packet analysis
unit is positive. Figure 11.24 shows the state diagram for the interrupt procedure. The
interrupt process unit will go back to the idle state after sending an interrupt signal to
the processor.
11.4.2.6 Command Control Unit
The command control unit (Figure 11.25) fetches control commands from the processor,
such as read and write data to FIFO, update Tag ID or Group=Owner ID, starts the
transmission procedure, and so forth.
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