ST STM32 Nucleo User manual

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UM2063
User manual
STM32 TCPM Application
Introduction
This document describes the STM32 USB-PD (Power Delivery) Expansion Package for
STM32Cube, referenced as X-CUBE-USB-PD.
To discover all our MCU based solutions for USB Type-C™ and Power Delivery technology
please go to our landing page https://www.st.com/content/st_com/en/stm32-usb-c.html.
X-CUBE-USB-PD is a USB-IF certified Expansion Package and consists of libraries, drivers,
sources, APIs and application examples running on STM32F0 Series microcontrollers
acting as USB Type-C™ port manager (TCPM).
The provided example helps to develop applications based on USB-PD DRP (Dual Role
Power).
The core of the stack is delivered in library format while the open-source format device part
offers a high level of flexibility to match the design considerations.
This Expansion Package supports one hardware implementation:
•Standardized TCPM/TCPC solution for any STM32 microcontroller
– Ideal solution to upgrade legacy design based-on any STM32 with USB-C™
– Lowest memory footprint and easy porting within the Cortex®-M series
– USB-PD 2.0/3.0+PPS compliant, multi-port
– Tested with TCPC controller from On-SEMI FUSB307B. Refer to USB Type-C™
port manager (TCPM)/port controller (TCPC) evaluation board (DB3623).
www.st.com

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Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Acronyms and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 USB-C™ PD architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Architecture overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Specific case of TCPM/TCPC architecture . . . . . . . . . . . . . . . . . . . . . . . . 8
3 USB-PD ST application setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Examples description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1 USB-PD DRP (TCPM/TCPC architecture) . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1.1 Example setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.1.2 Application description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1.3 Library initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1.4 TCPM API description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5 Memory footprint of the EVAL_FUSB307_DRP example . . . . . . . . . . . 15
6 Frequently asked questions (FAQs) . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

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List of tables
Table 1. List of acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Table 2. USB-PD - Dual role port memory footprint (in bytes) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 3. Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

List of figures UM2063
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List of figures
Figure 1. USB Power Delivery architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 2. USB Type-C™ port manager to USB Type-C™ port controller interface . . . . . . . . . . . . . . . 8
Figure 3. ST firmware architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 4. Project structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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1 Overview
This document describes how to use the USB-PD library supporting STM32 32-bit
microcontrollers based on Arm®(a) cores, for regular use and to create a customized
application.
It covers the following topics to ease the use of the library:
•USB-PD standard overview
•USB-PD library architecture
•USB-PD stack usage description
1.1 Acronyms and abbreviations
a. Arm is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.
Table 1. List of acronyms
Term Meaning
API Application programming interface
CAD Cable detection module
CC Configuration channel
DFP Downstream facing port
DPM Device policy manager
DRP Dual role port
FW Firmware
HW Hardware
PD Power delivery
PE Policy engine
PRL Protocol layer
TCPC USB Type-C™ port controller
TCPCi USB Type-C™ port controller interface
TCPM USB Type-C™ port manager
UFP Upstream facing port
USB Universal serial bus
VDM Vendor defined messages

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1.2 References
•Universal Serial Bus Power Delivery Specification, Revision 3.0, Version 2.0, August
29, 2019
•Universal Serial Bus Type-C™ Cable and Connector Specification 2.0, August 2019
•Universal Serial Bus Type-C™ Port Controller Interface Specification, Revision 1.0,
Version 1.2, November 2016
•User manual Managing USB power delivery systems with STM32 microcontrollers
(UM2552)
•Application note USB Type-C™ Power Delivery using STM32xx Series MCUs and
STM32xxx Series MPUs (AN5225)
•ST wiki USBPD overview:
https://wiki.st.com/stm32mcu/wiki/USB_Power_Delivery_overview
•STM32CubeMonitor-UCDPD: https://www.st.com/en/product/stm32cubemonucpd

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2 USB-C™ PD architecture
2.1 Architecture overview
The USB Power Delivery specification document defines the communicating layers of a PD
device (either provider or consumer) as shown in Figure 1.
Figure 1. USB Power Delivery architecture
A PD3.0-capable device is assumed to be made up of at least one port, which can
•sink power (a consumer), source power (a provider), or toggle between the two roles
(dual role power)
•optionally communicate via USB
•communicate using SOP Packets
•optionally communicate using SOP Prime packets.
Where USB products support USB Power Delivery protocols a USB DFP is initially a Source
and a USB UFP is initially a Sink, although USB-PD enables the Source/Sink and the
DFP/UFP roles to be swapped.
Note: There is only one Source port and one Sink port in each PD communication between port
partners.
MS41457V2
Provider
Protocol
Policy engine
Device policy manager
Consumer
Protocol
Policy engine
Device policy manager
CC-lines
Physical layerPhysical layer

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2.2 Specific case of TCPM/TCPC architecture
Implementation of USB-PD function may also be achieved in a TCPM/TCPC architecture,
with a standardized interface between USB Type-C™ port manager (TCPM) and a simple
USB Type-C™ port controller (TCPC) with the goal of easing USB Type-C™ Power Delivery
implementations.
Figure 2. USB Type-C™ port manager to USB Type-C™ port controller interface
TCPC interface (TCPCi) is using an I2C link and an alert pin. USB Type-C™ port controller
interface Specification (TCPCi) defines the interface between the TCPM and the TCPC(s).
In this architecture, one TCPM may be used to drive multiple TCPCs.
Protocol (PRL) functionalities are shared between TCPM and TCPC. TCPC must manage:
•GoodCRC management
•Retransmission
ST firmware architecture is described in Figure 3:

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Figure 3. ST firmware architecture
•Device Policy Manager (DPM)
DPM’s role is to manage all the ports present in the application and to share the power
between them according to the capability of the connected port partners. Once the
negotiation of power has ended, an explicit contract is concluded between them.
DPM can manage VDM exchanges, to manage the alternate modes, only once an
explicit contract is established. This layer is the high level of the USB C power stack
and the place where the user defines the power strategy of its application.
•Policy Engine (PE) layer
The Policy Engine (PE) role is to drive the message sequences according to the sent
message and to its expected response. It allows negotiating power, establishing an
Explicit Contract for the power exchange.
The acceptance or the refusal of a request depends on the response of the DPM
towards a specific power profile.
The PE also handles the Vendor Defined Messages flow, allowing to discover, enter or

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exit specified modes according to those supported by both provider and consumer
sides.
•Protocol layer high (PRL layer high)
This layer’s role is to construct, transmit and receive messages from/to TCPC layers
to/from the PE layer.
It interacts with the TCPM layer to transmit messages to TCPC through the TCPCi
interface.
•Type-C™ protocol management (TCPM)
This layer must handle messages exchanged between PRL and TCPC layers. It
means the management of alerts raised by TCPC, wrap communications, and others.
•Type-C™ protocol controller (TCPC) component
This layer is used to define all the registers accesses linked to TCPC component used
for Type-C™
•Type-C™ protocol controller interface (TCPCi)
This layer manages all the I2C transactions between TCPM and TCPC and also
interruptions linked to alerts.
•TCPC hardware
This layer is responsible for sending and receiving messages across the CC wires.
The TCPC hardware implements the entire USB-PD PHY layer with BMC encoding.
The TCPC implements a portion of the protocol layer transmission state diagram.
– CRCReceiveTimer
– RetryCounter
– Messages that are received are passed to the TCPM via I2C
– BIST handling
Note: For more information about the USB Power Delivery protocol, refer to the official
specification document mentioned in Section 1.2.