ZAURA Datasheet, PDF (18/99 Pages) –

ZAURA RF Wireless Library
Programmer’s Reference Manual
6
This transfer mechanism requires the recipient of an SDATA frame to
provide feedback if the frame is actually received. This feedback arrives
in the form of an Acknowledgement (ACK) frame. Reception of an ACK
informs the transmitter that the recipient received the SDATA frame as
well as whether the SDATA frame was accepted or rejected (invalid
sequence number or no buffer space); it can optionally request the trans-
mitter to delay the transmission of the next directed frame (reliable or
unreliable) targeting the requestor.
If a transmitter does not receive an ACK within a certain period of time
after transmitting an SDATA frame, it will automatically retransmit the
frame a user-configurable number of times before it aborts the transmis-
sion. If an ACK has not been received after exhausting all retransmission
attempts, the transmitting application should not assume that the target
failed to receive the SDATA frame. In this instance, the user application
must perform some form of polling to determine if the target actually
received the frame.
When a wireless node retransmits a frame, it is possible for the target to
receive multiple copies of the same frame. Therefore, ZAURA RF Wire-
less SDATA frames carry a sequence number and a retransmission bit that
recipients use to distinguish between new and duplicate frames.
Frame Formats
The ZAURA RF Wireless Network can be configured to use one of three
different frame formats: DA, DA_SA and DA_SA_CTRL. These frame
formats differ in the length of the header included in every frame. Extra
header bytes reduce the effective data rate of the RF channel but allow for
more complex data transfer modes (e.g., reliable data transfer). A user-
configurable frame format allows the ZAURA RF Wireless Network to be
deployed in a wide range of applications. For proper communications, all
nodes within a ZAURA RF Wireless cell must be configured to use the
same frame format.
The ZAURA RF Wireless Library
RM006003-1011