I did some more investigations from the Datasheet!
The MC13213 System in Package (SiP) integrates the MC9S08GT MCU with the MC1320x transceiver
into a single 9x9mm LGA package. The MC13213 provides 60 K Flash memory and 4 K of RAM. By
using the IEEE 802.15.4 Compliant MAC, or BeeStack ZigBee Protocol Stack.
Specifically it's a ZigBee 2006 compliant platform.
Now about the packets, there is nothing to reverse.
The packet structure and command formats are available in the manual.
The ZSTAR3 uses a simple time based protocol for an RF transfer of information between sensor boards
and the USB receiver. The protocol is based on a simple star topology for a communication network, with
one master point (USB stick) and slaves (sensor boards). It provides time slots for up to 16 sensors. Main
data of a load contains acceleration (X, Y and Z axis) and basic status data. The protocol is built on top of
modified Section 5.2, Simple Media Access Controller (SMAC) drivers that are available for the
MC1319x and MC1321x transceivers families. It is bidirectional, allowing the set up of independent
connections for up to 16 ZSTAR3 demos, together in one RF space (thus, up to 256 sensor boards).
All data is transferred in so-called Zpackets. This protocol is primarily targeted at simple demo purposes,
allowing a fast transfer of the accelerometer data in short packets with minimum overheads and with
minimum battery loads (most of the receive windows eliminated, short transmit packets, etc.).
So basically the stack layer is organized as follow:
RF Zig bee <-> SMAC <-> ZStar
As on Page 35 of the ZStarReference Manual.
Next step I will try to do a NodeDiscovery with my Xbee 2.5 series and see if it can see the sensors.
Another issue is that the NetNum is not related to the XBee address, so I have no idea how the MC is configured in terms of PAN and ID address.
Well if it doesn't work I guess you need to buy the usb key adapter!