USB TCPM software eases migration to USB-PD 3.0 power delivery

11th June 2018

Enaie Azambuja

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Helping engineers leverage the latest USB Power Delivery capabilities and versatile USB Type-C connections in new or legacy product designs, STMicroelectronics has introduced software for implementing a Type-C Port Manager (TCPM) on any general-purpose STM32 microcontroller.

Compliant with the USB Type-C Port Controller Interface (TCPCi) specification, and designed to manage a separate single- or multi-port Type-C Port Controller (TCPC) chip, ST’s X-CUBE-USB-PD stack implements the protocol layer and policy engine of the USB Power Delivery Specification (USB-PD 3.0 v1.1).

The stack demands minimal STM32 resources, having a low memory footprint and using only a single I2C bus address and one alert pin per port. In addition, standard register maps ensure easy interoperability with any connected TCPC device.

X-CUBE-USB-PD supports all USB-PD 3.0 options, including Programmable Power Supply (PPS) for connecting fast chargers, Fast Role Swap (FRS) for seamless user experiences during cable insertion or removal, and authentication-message exchange to allow data or power transfer only with genuine devices or chargers.

By supporting Provider, Consumer, and Dual-Role (DRP) modes, the stack enables product designers to leverage the benefits of USB Type-C in a wide variety of equipment types, such as power hubs or power banks, docking stations, game controllers, PC peripherals, multi-function accessories, and small appliances such as cordless vacuum cleaners, portable speakers, lighting products, proprietary chargers, and many other applications.

ST has tested the stack with ON Semiconductor’s FUSB307B, a USB-PD 3.0 v1.1-certified TCPC chip, creating a fully certified and ready-to-use solution that centralises the TCPM for multiple USB-PD ports.

The FUSB307B provides a 1Mbps I2C microcontroller interface and handles functionality such as plug-insertion/orientation detection and dead-battery power-up. Time-critical Power-Delivery functions that offload the microcontroller effectively enable any STM32 including entry-level devices to manage multi-port, multi-role USB-PD interfaces.

X-CUBE-USB-PD currently contains libraries tested on STM32 Arm Cortex-M0 and Cortex-M4 microcontrollers, giving developers a choice of over 420 different part numbers. Libraries for other STM32 series will be introduced by the end of 2018.

An ON Semiconductor FUSB307B evaluation board, ON-FUSB3-STM32, is also available to help streamline development. The board, which features a STM32F072 microcontroller and a USB-C connector, demonstrates control of a single port.