In a typical Zigbee network, devices will automatically join the network and pick the best parent to join. The device will join as high up the tree as possible and will join the parent that has the highest LQI. In some applications, a more controlled topology may be required. The NLME direct join request in the Z-Stack can be utilized to accomplish this. This design note describes a particular scenario in which this function might be used. The scenario is to let an end device (RFD) join the network normally, and then provide a means for it to join a specific router (FFD). The setup of the example consists of a coordinator, router, and end device. Since the end device is assumed to be in range of the coordinator, it will first join the coordinator on power up. Then, a joystick action causes the router to allow the end device to directly join it. Another joystick action tells the end device to leave the network and then re-join at the router. The following code snippets explain stepby-step how this is accomplished. This is applicable to the Z-stack 1.4.3 release.

http://www.ti.com/lit/swru124