Among the many consumer products Cardinal Peak is involved with, we have worked on multiple true wireless earbuds projects. These systems have several unique engineering challenges beyond your standard Bluetooth wireless headphones.
The first challenge is coordinating the actions of multiple independent devices (left bud, right bud, smart case and audio source) into one cohesive system. Part of the challenge here is that the reference designs from the silicon vendors are often not sufficient. Therefore, it is left to the development to build out additional components to incorporate into a robust system. With truly wireless earbuds, increasing battery size is not an option, so the second major challenge is minimizing power as needed.
This case study is particularly focused on the system issues of embedded software engineering (the state machine) and how they impact user experience and power consumption.
What are True Wireless Earbuds (TWE)?
True wireless Bluetooth earbuds are two separate Bluetooth earbud devices communicating wirelessly between each other and an audio source to provide convenient cord-free access for on-the-go music streaming, remote gaming and hands-free voice/video calling. Often, a smart charging case is integrated into the system as well. When included with extended features such as noise cancellation, voice assistant integration and biometric monitoring, the set is also referred to as a hearable (a hybrid of “wearable headphone”).
In 2020, true wireless earbuds were the most desired form factor for on-the-go headphone use, and adoption doubled from the previous year. Additionally, users demand the best audio fidelity without glitching or dropouts, and they want the most battery life possible between charges (9-18 hours).