Cadence extends battery life and improves user experience for wearables

Cadence Design Systems’ Tensilica HiFi 1 DSP has been designed to improve the user experience for small battery devices such as TWS earbuds, hearing aids, Bluetooth headsets, smart watches and other wearables.

The HiFi 1 DSP’s ultra-low energy consumption extends the duration of voice communication and music playback, allowing always listening to voice commands but with minimal impact on battery life. This will enable smaller form factors, lower-cost consumer and mobile devices, as well as automotive and industrial devices, while offering increased functionality with low energy consumption.

A number of converging trends are driving the need for low-energy audio/voice capabilities in a small form factor. Increasingly, hearables and wearables are adopting the Low Complexity Communications Codec (LC3) standardized by the Bluetooth Special Interest Group (SIG) in 2020. In addition, consumer preference for hands-free and touch-free control is driving demand for always-on, or always-listening, devices that respond to voice wake-up commands, and appliances are even adopting these capabilities. To deliver on these trends a small form factor and longer battery life are crucial.

“The Low Complexity Communication Codecs (LC3 and LC3plus) co-invented by Fraunhofer help limit energy consumption for battery-constrained Bluetooth devices. Fraunhofer and Cadence have a long history partnering on various codecs including LC3/LC3plus, which Cadence has optimised on its Tensilica HiFi DSPs,” said Manfred Lutzky, Head of Audio for Communications department at Fraunhofer IIS.

“We’re pleased to see them building upon that experience with the new HiFi 1 DSP that is energy- and cycle-optimised for LC3 and LC3plus. The HiFi 1 DSP embodies the codec’s ultra-low energy levels, which should bring relief to small battery hearable and wearable devices with added features and help accelerate the widespread adoption of LC3 and LC3plus.”

The HiFi 1 DSP delivers ultra-low energy encoding and playback of LC3 and other Bluetooth codecs and ultra-low energy keyword spotting for voice wake-up, all in the smallest footprint HiFi DSP. Compared to the HiFi 3 DSP, the most popular audio DSP in the industry for the target applications, the HiFi 1 DSP offers:

● 11 to 16% lower area
● 60 to 73% greater cycle and energy efficiency for ML-based “OK Google” keyword spotting and person detect applications
● Greater than 18% cycle efficiency and 14% energy efficiency for LC3 decoding

“The HiFi 1 DSP from Cadence significantly lowers the energy required to run the always-on class of AI applications, such as the TensorFlow Lite Micro (TFLM) networks, speech wake word and person detect, enabling battery-constrained devices to run for longer lengths of time,” said Pete Warden, technical lead of TFLM at Google.

“Cadence and Google have long collaborated on TFLM, and we are excited to continue the collaboration as Cadence pushes the boundaries of energy and performance further.”

HiFi 1 DSP Features and Benefits:

● Special instructions including arithmetic coding for LC3 encode and decode make the HiFi 1 DSP capable of delivering energy-efficient Bluetooth LE Audio
● Instructions for ITU-T3GPP-standardised 2019 BASOPs accelerate speech codecs and run them with high energy efficiency, increasing talk time
● Neural network ISA and load/store accelerate keyword spotting and other machine learning workloads for reduced energy consumption, while memory access-optimised ISA reduces improves performance with small cache sizes
● Efficient signal processing reduces energy and cycles for audio and speech pre- and post-processing
● Optional, low-latency vector floating point unit (VFPU) delivers higher FP throughput with lower energy consumption.
● Vector bool register improves energy efficiency for conditional code

“HiFi DSPs enjoy wide adoption in current-generation TWS earbuds and Bluetooth headsets,” said David Glasco, vice president of research and development for Tensilica IP at Cadence. “The advent of LC3 and wider market trends set the stage for next-generation hearables to offer a superior user experience and longer battery life. With many speech and voice algorithms migrating towards AI, we’re also seeing vastly expanding use cases for analytics and better sound quality in TWS earbuds.”