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WLC PTx EPP: Wireless power transmitter EPP application

This code example demonstrates the wireless charging power transmitter EPP function with USB-PD sink as the power input.

View this README on GitHub.

Provide feedback on this code example.

Requirements

Supported toolchains (make variable 'TOOLCHAIN')

  • GNU Arm® embedded compiler v9.3.1 (GCC_ARM) - Default value of TOOLCHAIN
  • Arm® compiler v6.13 (ARM)
  • IAR C/C++ compiler v8.4 (IAR)

Supported kits (make variable 'TARGET')

  • WLC1 15W Reference Board: REF_WLC_TX15W_C1 (WLC1115-68LQXQ) – Default value of TARGET

Hardware setup

  1. Connect the board to your PC using the USB cable through the KitProg3 USB connector. This cable is used for programming the WLC1 device. It is also used during debugging.

  2. Connect the USBPD port to the USB-C power adapter. This cable is used for the USB power delivery source and it provides power to the user LED.

See the kit user guide for more details on configuring the board.

Software setup

This example does not require additional software or tools.

Using the code example

Create the project and open it using one of the following:

In Eclipse IDE for ModusToolbox™ software
  1. Click the New Application link in the Quick Panel (or, use File > New > ModusToolbox Application). This launches the Project Creator tool.

  2. Pick a kit supported by the code example from the list shown in the Project Creator - Choose Board Support Package (BSP) dialog.

    When you select a supported kit, the example is reconfigured automatically to work with the kit. To work with a different supported kit later, use the Library Manager to choose the BSP for the supported kit. You can use the Library Manager to select or update the BSP and firmware libraries used in this application. To access the Library Manager, click the link from the Quick Panel.

    You can also just start the application creation process again and select a different kit.

    If you want to use the application for a kit not listed here, you may need to update the source files. If the kit does not have the required resources, the application may not work.

  3. In the Project Creator - Select Application dialog, choose the example by enabling the checkbox.

  4. (Optional) Change the suggested New Application Name.

  5. The Application(s) Root Path defaults to the Eclipse workspace which is usually the desired location for the application. If you want to store the application in a different location, you can change the Application(s) Root Path value. Applications that share libraries should be in the same root path.

  6. Click Create to complete the application creation process.

For more details, see the Eclipse IDE for ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/ide_{version}/docs/mt_ide_user_guide.pdf).

In command-line interface (CLI)

ModusToolbox™ software provides the Project Creator as both a GUI tool and the command-line tool, "project-creator-cli". The CLI tool can be used to create applications from a CLI terminal or from within batch files or shell scripts. This tool is available in the {ModusToolbox™ software install directory}/tools_{version}/project-creator/ directory.

Use a CLI terminal to invoke the "project-creator-cli" tool. On Windows, use the command line "modus-shell" program provided in the ModusToolbox™ software installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ software tools. You can access it by typing modus-shell in the search box in the Windows menu. In Linux and macOS, you can use any terminal application.

This tool has the following arguments:

Argument Description Required/optional
--board-id Defined in the <id> field of the BSP manifest Required
--app-id Defined in the <id> field of the CE manifest Required
--target-dir Specify the directory in which the application is to be created if you prefer not to use the default current working directory Optional
--user-app-name Specify the name of the application if you prefer to have a name other than the example's default name Optional

The following example will clone the "WLC1 EPP Power Transmitter" application with the desired name "WLC1_EPP_Power_Transmitter" configured for the WLC1115-68LQXQ BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id WLC1115-68LQXQ --app-id mtb-example-wlc1-ptx-epp --user-app-name mtb-example-wlc1-ptx-epp --target-dir "C:/mtb_projects"

Note: The project-creator-cli tool uses the git clone and make getlibs commands to fetch the repository and import the required libraries. For details, see the "Project creator tools" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

In third-party IDEs

Use one of the following options:

  • Use the standalone Project Creator tool:

    1. Launch Project Creator from the Windows Start menu or from {ModusToolbox™ software install directory}/tools_{version}/project-creator/project-creator.exe.

    2. In the initial Choose Board Support Package screen, select the BSP, and click Next.

    3. In the Select Application screen, select the appropriate IDE from the Target IDE drop-down menu.

    4. Click Create and follow the instructions printed in the bottom pane to import or open the exported project in the respective IDE.


  • Use command-line interface (CLI):

    1. Follow the instructions from the In command-line interface (CLI) section to create the application, and then import the libraries using the make getlibs command.

    2. Export the application to a supported IDE using the make <ide> command.

    3. Follow the instructions displayed in the terminal to create or import the application as an IDE project.

For a list of supported IDEs and more details, see the "Exporting to IDEs" section of the ModusToolbox™ software user guide (locally available at {ModusToolbox™ software install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

  1. Ensure that the steps listed in the Hardware setup section are completed.

  2. Program the board using one of the following:

    Using Eclipse IDE for ModusToolbox™ software
    1. Select the application project in the Project Explorer.

    2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4).

    Using CLI

    From the terminal, execute the make program command to build and program the application using the default toolchain to the default target. The default toolchain and target are specified in the application's Makefile but you can override those values manually:

    make program TARGET=<BSP> TOOLCHAIN=<toolchain>
    

    Example:

    make program TARGET=WLC1115-68LQXQ TOOLCHAIN=GCC_ARM
    

Debugging

You can debug the example to step through the code. In the IDE, use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. Ensure that the board is connected to your PC using the USB cable through the KitProg3 USB connector. See the "Debug mode" section in the kit user guide.

For more details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ software user guide.

Design and implementation

Figure 1. Firmware flowchart


The firmware operation is divided into three sections:

Initialization

The application firmware entry happens when the bootloader detects a valid firmware image and jumps to the specified address. The firmware first verifies the configuration information stored in flash by calculating the checksum of the table and comparing against the value stored in the table. If the checksum does not match, it automatically switches to the bootloader mode for flashing. When a valid configuration table is identified, the firmware proceeds to initialize the peripheral blocks and then enables the various system interrupts.

Main task loop

The main task loop is an infinite loop executing the specific set of tasks periodically. These tasks get executed sequentially as shown in Figure 1.

  • Qi tasks: The Qi FW module only processes high priority tasks inside the interrupt context or inside blocked critical sections. It then stores various Qi-specific interrupts and pending events and the main task loop continuously executes a Qi state machine task function which performs the actual handling. The solution manager handlers are invoked from inside this task function.

  • PD tasks: The PD FW module only processes high priority tasks inside the interrupt context. It then stores various PD-specific interrupts and events in an event bit mask. The main task loop continuously executes a PD scheduler task functionz, which performs the actual handling. The solution manager handlers are invoked from inside this task function.

  • HPI tasks: WLC communicates with the host processor/application processor for handling device-common commands and WiCG-specific commands. This task processes any host processor requests. Please refer to the WiCG host processor interface document, JRND-55, for more details.

  • Console tasks: WLC provides console interface through a UART peripheral for solution status logging. This task collects console print requests in the console queue from various modules and processes them based on request priority or verbosity level.

  • Instrumentation tasks: The instrumentation task mainly monitors the firmware state and provides a recovery path in system error events such as WDT software and hardware reset and stack overflow etc.

Low Power mode

Sleep mode is not used in the general WLC stack implementation, as all of the tasks are implemented in the form of state machines that can have incremental work to be completed.

The WLC devices support a low power mode called Deep Sleep. In this mode, the IMO is disabled and only ILO is functional. WLC attempts to stay in Deep Sleep mode for as long as possible when no Qi object is detected, waking up only long enough to perform any work triggered due to incoming Qi or Type-C or PD events or I2C-based requests.

QiStack

Figure 2. QiStack components

  • Qi Policy manager: The Qi Policy Manager (QPM) is the top layer and maintains the core stack state machine. It interacts with the HAL layer and low-level Qi modules such as the communication manager, object manager, and power manager for configuration, monitoring, request, control, and event handling.

  • Communication manager: Qi uses amplitude shift keying (ASK) and frequency shift keying (FSK) for in-band communication between the transmitter and receiver. ASK is the communication mode from Rx to Tx, while FSK is the communication mode from Tx to Rx.

  • Object manager: The Qi transmitter detects the object and the type of object on its coil surface before initiating power transfer and also while power transfer is in progress. The object can either be Rx only or FO only or RX + FO.

  • Power manager: The power manager handles the inverter, coil voltage/current, and PID loop methods.

The QiStack middleware library implements the state machines defined in the Wireless Power Consortium Qi v1.3.2 .

PDStack

The PDStack middleware library implements the state machines defined in the USB Type-C cable and connector and the USB Power Delivery specifications. PDStack consists of the following main modules:

  • Type-C manager: Responsible for detecting a Type-C connection and identifying the type of connection. It uses the configurable Rp/Rd terminations provided by the USBPD block and the internal line state comparators. The Type-C manager implements the state machines defined in the USB Type-C cable and connector specification and provides the following functionality:

    • Manage CC terminations: Applies Rp/Rd terminations according to the port role

    • Attach detection: Performs the required debounce and determines the type of device attached

    • Detach detection: Monitors the CC line and Vbus for detecting a device detach

  • Protocol layer: Forms the messages used to communicate between a pair of ports/cable plugs. It is responsible for forming capability messages, requests, responses, and acknowledgements. It receives inputs from the policy engine indicating which messages to send and relays the responses back to the policy engine.

  • Policy engine: Provides a mechanism to monitor and control the USB Power Delivery system within a particular consumer, provider, or cable plug. It implements the state machines defined in the USB Power Delivery specification and contains implementations of all PD atomic message sequences (AMS). It interfaces with the protocol layer for PD message transmission/reception for controlling the reception of message types according to conditions such as the current state of the port. It also interfaces with the Type-C manager for error conditions such as Type-C error recovery.

  • Device policy manager (DPM): Provides an interface to the application layer to initialize, monitor, and configure the PDStack middleware operation. The DPM provides the following functionality:

    • Initialize the policy engine and Type-C manager

    • Start the Type-C state machine followed by the policy engine state machine

    • Stop and disable the Type-C port

    • Allow entry/exit from Deep Sleep to achieve low power based on the port status

    • Provide APIs for the application to send PD/Type-C commands

    • Provide event callbacks to the application for application-specific handling

The PDStack library uses a set of callbacks registered by the application to perform board-specific tasks, such as turning the consumer power path ON/OFF and identifying the optimal source power profile to be used for charging. In this example, these functions are implemented using the appropriate APIs provided as part of the peripheral driver library (PDL).

The stack also provides notification of various connection and PD policy state changes so that the rest of the system can be configured as required. These events are used by the example application to implement a separate USB Battery Charging 1.2 sink state machine, which distinguishes between a standard downstream port (SDP), charging downstream port (CDP), and dedicated charging port (DCP).

Bootloader

The WLCx bootloader is a fixed function firmware segment, which is factory-programmed and provides firmware upgrade and configuration update functionality over the I2C and CC interface.

Deep Sleep

The application tries to keep the WLCx MCU device in Deep Sleep, where all clocks are disabled and only limited hardware blocks are enabled for most of its working time. Interrupts in the USBPD block are configured to detect any changes that happen while the device is in sleep, and wake it up for further processing.

Fault protection

  • Type-C VBUS undervoltage protection (VBUS UVP): Incorporates a dedicated voltage comparator with an integrated digital filter that detects undervoltage on the Type-C VBUS. On VBUS undervoltage detection, the VBUS and buck-boost regulator are turned off to protect onboard components as well as the external sink devices. Voltage levels to detect undervoltage, debounce period, and retries are configurable through the Wireless Charging Configuration Utility.

  • Type-C VBUS overvoltage protection (VBUS OVP): Incorporates a dedicated voltage comparator with an integrated digital filter that detects overvoltage on the Type-C VBUS. Type-C VBUS overvoltage handling and configurability are similar to VBUS UVP.

  • Type-C VBUS overcurrent protection (VBUS OCP): Incorporates a current sense amplifier and a dedicated comparator with an integrated digital filter that detects overcurrent on the Type-C VBUS. Type-C VBUS overcurrent handling and configurability are similar to VBUS UVP.

  • Type-C VBUS Short-circuit protection (VBUS SCP): Shares the current sense amplifier with VBUS OCP and incorporates a dedicated comparator with an integrated digital filter that detects overcurrent on Type-C VBUS. The debounce period and retries are configurable through the Wireless Charging Configuration Utility.

  • VIN undervoltage protection (VIN UVP): Supports comparator-based VIN UV detection and also supports Auto Provider FET cut-off.

  • VIN overvoltage protection (VIN OVP): Supports comparator-based VIN OV detection and also supports Auto Provider FET cut-off.

  • VREG inrush current limit: Incorporates protection against large current load on VDDD (internal regulator). This helps to avoid VDDD droop because of inrush and also unknown behavior of the device and possible brownout. The port is disabled (buck-boost turned off) after a fault is detected and device software reset is executed to recover from VDDD fault. Device reset is necessary because any misbehavior in VDDD needs to reset the device completely to start fresh firmware/hardware execution.

  • VDDD brown-out detection (VDDD BOD): VDDD can enter the hardware brown-out level because of lower voltage or GND short on VDDD or inrush current. A software brown-out detection helps to exit the context or state cleanly by disabling buck-boost regulation and other components.

Compile-time configurations

The WLCx MCU USBPD sink application functionality can be customized through a set of compile-time parameters that can be turned ON/OFF through the config.h header file.

Table 1. Compile time configurations

Macro name Description Allowed values
CY_PD_SINK_ONLY Specifies that the application supports only the USBPD sink (consumer) role Should be set to 1u
CY_PD_REV3_ENABLE Enable USBPD Revision 3.0 support 1u or 0u
BATTERY_CHARGING_ENABLE Enables BC 1.2 (CDP/DCP) detection when connected to a non-USBPD power source 1u or 0u
SYS_DEEPSLEEP_ENABLE Enables device entry into deep sleep mode for power saving when the CPU is idle 1u or 0u
APP_VBUS_SRC_FET_BYPASS_EN Enables No Provider FET configuration 1u or 0u
QC_SRC_AFC_CHARGING_DISABLED Disables QC and AFC protocol support in state machine 1u or 0u
VREG_INRUSH_DET_ENABLE Enables Vreg inrush detection fault 1u or 0u
VREG_BROWN_OUT_DET_ENABLE Enables VDDD brown-out fault detection 1u or 0u
BB_ILIM_DET_ENABLE Enables buck-boost Ilim fault detection 1u or 0u
VBTR_ENABLE Enables hardware-based voltage transition slew rate 1u or 0u
VIN_OVP_ENABLE Enables overvoltage protection fault over VIN 1u or 0u
VIN_UVP_ENABLE Enables undervoltage protection fault over VIN 1u or 0u
VBUS_OCP_ENABLE Enables overcurrent protection fault over VBUS 1u or 0u
VBUS_SCP_ENABLE Enables short circuit protection fault over VBUS 1u or 0u
VBUS_UVP_ENABLE Enables undervoltage protection fault over VBUS 1u or 0u
VBUS_OVP_ENABLE Enables overvoltage protection fault over VBUS 1u or 0u

PDStack library selection

The USB Type-C connection manager, USB Power Delivery (USBPD) protocol layer, and USBPD device policy engine state machine implementations are provided in the form of pre-compiled libraries as part of the PDStack middleWare library.

Multiple variants of the PDStack library with different feature sets are provided; you can choose the appropriate version based on the features required by the target application.

  • WLC1_PD3_SNK: Library with support for USB Type-C sink operation and USBPD Revision 3.0 messaging. This library can be used in any Power-Delivery WLCx application.

The library of choice can be selected by editing the Makefile in the application folder and changing the value of the COMPONENTS variable.

Device configuration

The properties of the device parameters, wireless configuration, and USB PD configuration including the port role and the default response to various USBPD messages can be configured using the Wireless Charging Configuration Utility.

These parameters have been set to the appropriate values for a Power Delivery sink application by default.

Wireless charger configuration

Figure 3. Qi configuration using Wireless Charging Configuration Utility


  • Qi main configuration: The Qi main configuration details such as profile, mode, packet timeout, and EPT counter parameters.

  • Coils: Configure the parameters specific to the coil.

  • Qi foreign object detection (FOD) configuration: Configure Qi foreign object detection (FOD) Q factor parameters of the coil

  • Vin configuration: Enables/Disables dynamic PD contract selection based on PRx requirements to optimize power usage.

  • Fault-protection configuration: Configure parameters for the protection mechanisms.

PD configuration

Figure 4. USB Type-C port configuration using Wireless Charging Configuration Utility


Properties of the USB-C port are configured using the Port Information section. Because this application supports only the USBPD sink operation, the Port Role must be set as Sink and DRP Toggle must be disabled. Other parameters such as Manufacturer Vendor ID and Manufacturer Product ID can be set to desired values.

The Source PDO and SCEDB Configuration sections are not applicable for this application because only the sink operation is supported.

Figure 5. Sink capability configuration using Wireless Charging Configuration Utility


The power capabilities supported by the application in the sink role are specified using the Sink PDO section. See the USB Power Delivery specification for details on how to encode the various sink capabilities. A maximum of seven PDOs can be added using the configurator.

Figure 6. Extended sink capability configuration using Wireless Charging Configuration Utility


The SKEDB section is used to input the extended sink capabilities response that will be sent by the application when queried by the power source. See the Power Delivery specification for details on the extended sink capabilities format.

Once the parameters are updated as desired, save the configuration and build the application.

Resources and settings

Table 2. Application Resources

Resource Alias/object Purpose
USBPD PD_PORT0 USBPD block used for PD communication

List of application files and their usage

Table 3. Application files

File Purpose
app_version.h Version definition for the WLC firmware application. It follows an Infineon-defined format that identifies the type of application along with the version information
ccgx_version.h Defines the base firmware stack version for CCGx
config.c This source file contains the default run-time configuration for the CCGx application and has been generated using the Wireless Charging Configuration Utility
config.h Header file that enables/disables firmware features and provides macros or function mappings for hardware-specific functions such as FET control and voltage selection.
fault.c This source file contains the solution layer implementation for fault protection
fault.h Header file that enables/disables solution layer fault protections
solution.c This source file provides various user configurations, user hardware-specific functions, and custom code modules
solution.h Header file for solution-specific implementation
main.c This source file contains the main application entry point

Related resources

Table 4. Resource information

Resources Links
Code examples on GitHub Using ModusToolbox™ software
Device documentation WLC1 datasheets
Development kits Visit WLC1
Libraries on GitHub mtb-pdl-cat2 – Peripheral driver library (PDL) and docs
Middleware on GitHub pdstack – PDStack middleware library and docs
qistack – QiStack middleware library and docs
ccgxAppCommon – Application specific files for CCGx Projects
wlchpi - Host Processor Interface Module
Tools Eclipse IDE for ModusToolbox™ software
ModusToolbox™ software is a collection of easy-to-use software and tools enabling rapid development with Infineon MCUs, covering applications from embedded sense and control to wireless and cloud-connected systems using AIROC™ Wi-Fi & Bluetooth® combo devices.
Wireless Charging Configuration Utility
The Wireless Charging Configuration Utility is a GUI-based Microsoft Windows application developed by Infineon to guide a user through the process of configuring and programming this chip.

Other resources

Infineon provides a wealth of data at https://www.infineon.com/cms/en/product/power/wireless-charging-ics to help you select the right device, and quickly and effectively integrate it into your design.

Document history

Document Title: CE235394WLC PTx EPP: Wireless power transmitter EPP application

Version Description of change
1.0.0 New code example



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