Self-contained low power Wi-Fi IP for IoT apps

The emerging theme of fit-for-purpose IoT parts gained yet another perspective, this time with ARM and CEVA chiming in on a low-power Wi-Fi approach outlined in a new webinar. It was a rather unique event with an abbreviated 25-minute presentation and an extended 35-minute Q&A that added a lot of insight.

CEVA is betting heavily on two data points. First is a rough estimate I’m not sure I believe entirely: a calculation courtesy of Green Peak saying if there are 600M+ households all converted to smart homes with 100+ nodes each, it adds up to 60B nodes. Obviously the math is correct, and I know and respect Cees and his guys, but I don’t think the penetration in the smart home is that wide or that deep anytime soon. That said, I do think the opportunity for Wi-Fi in the smart home is significant and worth customizing silicon.

Second is the segment getting a lot of air time: wearables. CEVA used this chart from Analysys Mason to guide their projection. I was reading something this morning saying Apple Watch shipments are actually expected to decline this year – despite Apple users loving the device and waiting for the 2[SUP]nd[/SUP] gen version, the general population isn’t as excited. Again, wearables are big; the question is if they will be huge. This projection will need more drive beyond Apple and Samsung, and as I’ve said previously Xiaomi may be the surprise here along with FitBit and Garmin. I do think Wi-Fi penetration in wearables will be better than many think, with one example coming up.

Inflated expectations tamped down a bit, one element that I am confident will trigger more IoT growth is low-power Wi-Fi IP. One point Franz Dugand of CEVA made effectively was that not all Wi-Fi IP is created equally. CEVA segments its RivieraWaves Wi-Fi platforms into three categories: stream, surf, and sense. What we’re really talking about here is the sense category, where CEVA is focused on self-contained IP that accelerates functions in hardware and offloads the CPU while handling the protocol stack.

Besides the usual treatments of functional and fine-grained clock gating plus power gating, CEVA has incorporated newer Wi-Fi technology in their IP to get the power down. They support WMM-Power Save, which naps between packets to save power while the access point buffers traffic. They also have done things like small retention memory with short wakeup times, and a software-defined AGC (automatic gain control) and CCA (clear channel assessment, part of carrier sense) that allows tuning or upgrading. Noteworthy is that CEVA doesn’t supply the radio itself, instead turning to Catena and Sabertek for RF expertise.

For their part, ARM focused on their core IoT story (pun intended) built around the Cortex-M3 and mbed OS. One reason for that is the mbed Device Connector, a cloud-service offering for IoT apps using simple REST APIs and lighter protocols like CoAP. One of the questions Mike Eftimakis was asked was what is special about ARM’s IoT IP to help save power. He pointed out they are doing things like caching flash.

CEVA and ARM have demonstrated the Wi-Fi Smart Home Station using an ARM FPGA-based prototyping platform with their combined IP and a daughter board with the Wi-Fi radio. One factoid: CEVA says one of their customers has achieved 5 days of 500Kb/s Wi-Fi transfers on one coin cell. Another question Franz addressed was how this compares to Bluetooth, and his answer should provoke some use case thought. He suggested Apple normally uses Bluetooth in the Apple Watch until there is something big to transfer like a map, then it switches to Wi-Fi. This is the classic work-per-unit-time argument that going faster for less time may save energy.

CEVA has a very competitive low power Wi-Fi IP solution for those looking to differentiate IoT parts through design. The complete archived webinar with the Q&A is informative, including CEVA’s answer to my question on HaLow and many other questions:

Low Power Wi-Fi for IoT