In a previous post my colleague Kevin McDermott laid out the processing requirements for IoT devices. He also touched upon the data rate requirements for IoT.
Today I’d like to talk about our Ensigma Whisper RPU architecture, a hardware connectivity engine optimally designed for IoT applications.
The Whisper family offers a unique and comprehensive range of multi-standard solutions for embedding low power wireless standards on chip. Whisper supports such popular connectivity standards as 802.11 b/g/n Wi-Fi, Bluetooth Smart, and 802.15.4 (the basis for 6LoWPAN, ZigBee, Thread, etc.).
Having already covered the Whisper low power Wi-Fi architecture in a previous post, I would like to touch on the architecture’s capabilities when it comes to supporting Bluetooth Smart and 802.15.4.
For Bluetooth Smart and 802.15.4, the relevant Whisper RPU system components are illustrated in the figure below:
The Ensigma RPU with baseband accelerator block includes an embedded controller as well as several accelerator blocks such as AES, Whitening CRC, Interleaver, BCH and others. The host processor interfaces to the Whisper RPU through a standard AXI interface. Other peripheral blocks such as UART or USB can also easily interface with the RPU through dedicated interfaces. The multi-standard modem supports GFSK modulation (for Bluetooth Smart) and/or O-QPSK PHY (for 802.15.4). The RF block features a Polar Modulation Transmitter with two frequency modulation points along with a Sliding IF Receiver ensuring ultra-low power consumption for IoT applications.
The Whisper Bluetooth Smart PHY/baseband module includes support for the following features@
- Advertising/scanning/initiation roles
- Master/slave roles
- Authentication/encryption with pause/resume
- Frequency hopping
The corresponding 802.15.4 PHY features include
- Coherent demodulation
- Shared hardware with Bluetooth Low Energy
- Support for FFD (end device, coordinator and PAN coordinator)
- Station function and hub function
Imagination works closely with Bluetooth/ZigBee stack partners to provide a complete solution for Bluetooth Smart and ZigBee/Thread. The three diagrams below illustrate the split between the stack running on the Whisper RPU and the one on the host processor, respectively:
The Ensigma Whisper RPU software stack for ZigBee
Imagination’s Whisper RPU architecture provides an end to end solution from software to RF thus ensuring that the the entire architecture is optimized to provide the smallest area footprint and the lowest power consumption. This makes Ensigma Whisper RPUs the ideal communication IP for ultra-low power IoT applications.