Wireless Stylus Charging

System Requirements

Goal: develop a pen and charging system with an intentionally designed experience, while meeting crucial technical requirements.

The engineering teams* depended on a comprehensive, documented, socialized, and verifiable system design, built on:

Coil alignment tolerances
Coil configurations (copper weight, number and span of turns), derived from requirements around coupling efficiencies and alignment volume
Full table of charging behavior: charge only when plugged in? What if system is asleep, or hibernating?
Impact to over-all battery life of host
Protocol for negotiating power levels
FOD (Foreign Object Detection) and mitigation: flowchart of behavior, to minimize energy loss and maximize responsiveness. This was a big deal.
Behavior of indicator light
Loosely coupled Bluetooth behavior
When & how to report percent of charge to host
Limiting level of full charge to extend battery life
Many other minute details

These system requirements drove design, engineering, and test validation workstreams through the whole end-to-end development process. The system shipped in 2019 and empowered multiple follow-on products following the same repeatable system design platform.

*Multi-disciplinary teams: ID, ME, EE, FW, SW, O/S, Nearshore Pen Engineering, Test / Validation teams, & Suppliers / Partners.

Testimonials

From a System Engineer at Microsoft:

"Carl is one of those rare individuals I can turn to when I need help influencing the organization, or convincing others of the right path, particularly when we’re dealing with systems of a high degree of technical complexity that impact stake holders across a variety of functional areas. I work with EE, FW, SW (Surface and Windows), UX (particularly User Research), MTE (manufacturing test), DVSE (design verification), as well as outside suppliers like our touch controller supplier, and it can be challenging to keep all these groups aligned. Carl is well known and respected across the business, and his involvement always adds credibility to what I’m trying to do."

From a PM at Accenture:

"I've been fortunate to have the opportunity to work with Carl. His technical leadership in new product development has been incredible. I've witness his significant impact to the project teams I've managed with his ability to mentor new and senior engineers, providing top-notch technical guidance to create innovative products, and continuously challenge the team to ensure project success as well as our clients' success."

From a Verification/System Director at Microsoft: