The USB-C: When the "Universal" standard is not uniformly implemented

In a recent project, we faced an interesting challenge with USB-C connectivity that showcased both the promises and complications of this universally adopted standard. In layman’s terms our task was straightforward: we needed an Android tablet to act as a communication master (host) while simultaneously receiving power as a sink device through a single USB-C port.

In theory, USB-C should handle this with ease. The standard supports bidirectional power delivery and various alternate modes that allow simultaneous data transfer and power delivery. Combined with USB On-The-Go (OTG) technology, which enables devices to switch between host and peripheral roles, it seemed like we had all the pieces of the puzzle.

However, through some research we discovered that theory and practice don't always align. Not all Android devices support simultaneous OTG and charging, even with a USB-C port. This feature requires specific implementation at both hardware and software levels by device manufacturers. Additionally, any solution would need to handle complex power delivery negotiations between devices while maintaining stable data communications.

After exploring various options, we settled on a simple yet effective solution: a USB OTG Y-cable with power injection. This special cable includes three connectors: a USB-C male connector for the tablet, a USB-A female connector for data communication, and a USB-A male connector for power input. This setup allowed our tablet to act as a USB host for communication while simultaneously receiving power for charging.

The Y-cable solution proved to be the most reliable and universally compatible than attempting to implement a direct USB-C connection, which would have required complex power negotiation protocols and might have faced compatibility issues across different tablet models. Sometimes, the simplest solution really is the best one.