TI Engineer's Annual Summary: Selected Q&A on Wireless Connectivity Technologies (ZigBee, Bluetooth, etc.)

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TI Engineer's Annual Summary: Selected Q&A on Wireless Connectivity Technologies (ZigBee, Bluetooth, etc.) [Copy link]

ZigBee technology related:

ZigBee PRO Specification

A. Subnode management

Child node management means that the parent node needs to monitor the neighbor table entries to see if they exceed the preconfigured timeout. If they do, they are "aged". The end device can update the timeout with the "Device Timeout Request" command. The child node sends a MAC data poll to reset the parent node's aging counter. Once the timeout value is exceeded and the child node has "aged", the parent node sends a leave request to the child node, which includes a rejoin attribute to allow the device to rejoin the network through a new parent node.

B. Parent Announce command

Zigbee3.0 stipulates that the parent node notification message is required on all routing devices (routers and coordinators) and is used to notify other routing devices known to child devices in the network. If a routing device previously in the network rejoins the network, the Parent Announce message is broadcast and sent 10 to 20 seconds after the device rejoins the network. The address is 0xFFFC.

C. TCLK update

R21 devices joining a Zigbee 3.0 centralized network must initiate the TC Link Key update procedure after joining the network. The node descriptor packet sent during the network association process can indicate the Zigbee version of the joining device. The coordinator (as a trust center) can be configured to accept or reject the assumption of legacy devices (i.e., not to initiate the TC Link Key update process). This feature increases memory consumption on the coordinator.

>>More Q&A selections: https://e2echina.ti.com/question_answer/wireless_connectivity/zigbee/f/104/t/185636

Bluetooth technology related:

1. Q: AOA measurement distance

A: The implementation of AOA depends on BLE connection. If BLE can be connected normally, AOA measurement can be performed. The specific distance depends on factors such as the experimental environment. It is recommended to use RF-RANGE-ESTIMATOR for evaluation.

2. Q: AOA measurement accuracy

A: The accuracy of AOA depends mainly on the measurement environment (multipath propagation, reflective surfaces, etc.) and the specific application part of the implementation. The routines provided by TI achieve an accuracy of about 5 degrees in an anechoic chamber.

3. Q: Measurement angle of AOA

A: Theoretically, each antenna array can cover 180 degrees, but the areas covered by the two arrays overlap [the angle between the two antenna arrays is 90 degrees], so theoretically the entire AoA boostpack can cover 270°, or ±135°. The actual measurement angle depends on the AOA algorithm implementation. The TI routine algorithm can measure an angle of ±100°.

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Hardware, RF and proprietary technology related:

The frequency of a crystal oscillator depends on the capacitive load value of the crystal. The crystal manual generally lists the optimal load capacitance of the crystal --- CL. This total CL usually includes the external load capacitance and the parasitic capacitance generated by the layout and package. Using external capacitors to obtain the correct frequency means that the internal capacitance must be set to the minimum value. For example, an application can use a minimum on-chip capacitance of about 2 pF and an off-chip capacitor of 7 pF to obtain a total load capacitance of 9 pF. CC13XX/CC26XX has an internally configured capacitance array. Normally, no external load is required and it is enough to adjust the internal capacitance directly.

The following takes CC2640R2F as an example to explain in detail the crystal oscillator selection and cap array adjustment.

1. Crystal oscillator selection

The chip's requirements for crystal oscillators are generally given in the chip's data sheet. The CC2640R2F datasheet has the following requirements:

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