User's Manual Part 2

ZSTAR RF protocol
Wireless Sensing Triple Axis Reference design, Rev. 0.9
Freescale Semiconductor 41
5.3.2.4 ZSTAR_ACK
This command is sent as the data acknowledgement so the Sensor Board board knows that the
connection is still alive. If the receive window is opened by the Sensor Board and the
ZSTAR_ACK has
not been received, the operation (periodic transmission of a
ZSTAR_DATA packet) continues but the
Sensor Board will try to receive an acknowledgement more frequently. If the acknowledgement is not
received several times, the connection is dropped and the Sensor Board will try to re-establish the
connection again. The USB stick will recognize this situation once several
ZSTAR_DATA packets have
not been received.
5.3.2.5 ZSTAR_CALIB
This command carries the calibration data provided by the USB stick for the Sensor Board and is sent
instead of a
ZSTAR_ACK packet. The calibration data is intended to be stored in Flash memory of the
Sensor Board. Since the Sensor Board does not receive after every
ZSTAR_DATA packet, the USB stick
keeps sending a
ZSTAR_CALIB until the Sensor Board confirms reception using a new
ZSTAR_CONNECT packet.
5.3.2.6 ZSTAR_STATUS
This command carries the g-range data provided by the USB stick for the Sensor Board and is sent
instead of a
ZSTAR_ACK packet. The g-range data is intended to switch the g-range of accelerometer
sensor. Since the Sensor Board does not receive after every
ZSTAR_DATA packet, the USB stick keeps
sending a
ZSTAR_STATUS until the Sensor Board confirms reception using a new ZSTAR_CONNECT
packet.