Kinetis W-Series Bit Streaming Mode (BSM)
The Kinetis W series are wireless platforms that have IEEE 802.15.4 2.4 GHz radio transceiver support. One of the features of the transceiver is the Bit Streaming Mode. This feature allows all 802.15.4 packet data, received or transmitted, to be serialized and shifted out to external hardware for further processing. It essentially exposes the traffic between the digital modem and link layer acceleration hardware meaning de-modulated Rx data and un-modulated Tx data. This data flow does not require MCU cycle time or any software processing on the KW silicon.
The implementation uses a simple, synchronous 3-wire interface:
For Kinetis KW2x for instance, this interface can be made available also on the package via the PTC3, PTC1 and PTC0 pins.
The BSM outputs can be consumed by an external system and generate packet trace data for all 802.15.4 traffic appearing on a network, within range of the KW device. This enables non-intrusive Personal Area Network (PAN) level monitoring and debugging. Such a setup usually a data consumer in the form of an external MCU or similar processing unit that acquires the data, processes it and forwards it to a system that can be accessed by the user (serial interface, display screen etc.).
The most powerful use case for this feature would be a complex, non-intrusive network analysis and “super-sniffer” solution, based on the data that reaches the node over the air, regardless of any filtering rules that might be in place at link layer level.