PSOC™ 4 HV: PACSS OCD

This code example demonstrates using the precision analog channel subsystem (PACSS) overcurrent detection (OCD) feature in the PSOC™ 4 HVPA family.

The application configures the OCD to monitor current through the shunt resistor and triggers interrupts when the current exceeds configured thresholds. The OCD operates independently of the ADC, providing fast overcurrent detection for battery protection applications.

View this README on GitHub.

Provide feedback on this code example.

Requirements

ModusToolbox™ v3.7 or later (tested with v3.7)
Board support package (BSP) minimum required version: 3.1.0
Programming language: C
Associated parts: PSOC™ 4 HV MCU

Supported toolchains (make variable 'TOOLCHAIN')

GNU Arm® Embedded Compiler v14.2.1 (GCC_ARM) – Default value of TOOLCHAIN
Arm® Compiler v6.22 (ARM)
IAR C/C++ Compiler v9.50.2 (IAR)

Supported kits (make variable 'TARGET')

PSOC™ 4 HVPA-SPM 1.0 Evaluation Kit (KIT_PSOC-HVPA-SPM1_LITE) – Default value of TARGET

Hardware setup

This code example requires a jumper wire connection between the OCD output pin P3[2] and the LED pin P2[6] on the board to visualize the OCD output state via the onboard LED.

Note: Some of the PSOC™ 4 HV kits ship with KitProg2 installed. ModusToolbox™ requires KitProg3. Before using this code example, make sure that the board is upgraded to KitProg3. The tool and instructions are available in the Firmware Loader GitHub repository. If you do not upgrade, you will see an error like "unable to find CMSIS-DAP device" or "KitProg firmware is out of date".

Software setup

See the ModusToolbox™ tools package installation guide for information about installing and configuring the tools package.

Install a terminal emulator if you do not have one. Instructions in this document use Tera Term.

This example requires no additional software or tools.

Using the code example

Create the project

The ModusToolbox™ tools package provides the Project Creator as both a GUI tool and a command line tool.

Use Project Creator GUI

Open the Project Creator GUI tool

There are several ways to do this, including launching it from the dashboard or from inside the Eclipse IDE. For more details, see the Project Creator user guide (locally available at {ModusToolbox™ install directory}/tools_{version}/project-creator/docs/project-creator.pdf)
On the Choose Board Support Package (BSP) page, select a kit supported by this code example. See Supported kits

Note: To use this code example 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
On the Select Application page:

a. Select the Applications(s) Root Path and the Target IDE

Note: Depending on how you open the Project Creator tool, these fields may be pre-selected for you

b. Select this code example from the list by enabling its check box

Note: You can narrow the list of displayed examples by typing in the filter box

c. (Optional) Change the suggested New Application Name and New BSP Name

d. Click Create to complete the application creation process

Use Project Creator CLI

The 'project-creator-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™ 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™ installation instead of a standard Windows command-line application. This shell provides access to all ModusToolbox™ 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.

The following example clones the "PACSS OCD" application with the desired name "PACSS_OCD" configured for the KIT_PSOC-HVPA-SPM1_LITE BSP into the specified working directory, C:/mtb_projects:

project-creator-cli --board-id KIT_PSOC-HVPA-SPM1_LITE --app-id mtb-example-ce242826-pacss-ocd --user-app-name PACSS_OCD --target-dir "C:/mtb_projects"

The 'project-creator-cli' tool has the following arguments:

Argument	Description	Required/optional
`--board-id`	Defined in the field of the BSP manifest	Required
`--app-id`	Defined in the 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

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™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Open the project

After the project has been created, you can open it in your preferred development environment.

Eclipse IDE

If you opened the Project Creator tool from the included Eclipse IDE, the project will open in Eclipse automatically.

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

Visual Studio (VS) Code

Launch VS Code manually, and then open the generated {project-name}.code-workspace file located in the project directory.

For more details, see the Visual Studio Code for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_vscode_user_guide.pdf).

Arm® Keil® µVision®

Double-click the generated {project-name}.cprj file to launch the Keil® µVision® IDE.

For more details, see the Arm® Keil® µVision® for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_uvision_user_guide.pdf).

IAR Embedded Workbench

Open IAR Embedded Workbench manually, and create a new project. Then select the generated {project-name}.ipcf file located in the project directory.

For more details, see the IAR Embedded Workbench for ModusToolbox™ user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mt_iar_user_guide.pdf).

Command line

If you prefer to use the CLI, open the appropriate terminal, and navigate to the project directory. On Windows, use the command-line 'modus-shell' program; on Linux and macOS, you can use any terminal application. From there, you can run various make commands.

For more details, see the ModusToolbox™ tools package user guide (locally available at {ModusToolbox™ install directory}/docs_{version}/mtb_user_guide.pdf).

Operation

Connect the board to your PC using the provided USB cable through the KitProg3 USB connector
Open a terminal program and select the KitProg3 COM port. Set the serial port parameters to 8N1 and 115200 baud
Program the board using one of the following:
Using Eclipse IDE
1. Select the application project in the Project Explorer
2. In the Quick Panel, scroll down, and click <Application Name> Program (KitProg3_MiniProg4)
In other IDEs

Follow the instructions in your preferred IDE.
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 is specified in the application's Makefile but you can override this value manually:
```
make program TOOLCHAIN=<toolchain>
```
Example:
```
make program TOOLCHAIN=GCC_ARM
```
After programming, the application starts automatically. Confirm that the terminal displays the current measurement values and OCD status information, including glitch filter counter and comparator status and it updates in real time as the current changes. You can adjust the current by rotating the potentiometer to test the OCD functionality

Figure 1. Terminal output
When current exceeds the OCD threshold, the terminal will display OCD interrupt messages. The glitch filter counter increments when the threshold is exceeded, and if it reaches the configured limit, the OCD output is triggered and the LED will turn on

Debugging

You can debug the example to step through the code.

In Eclipse IDE

Use the <Application Name> Debug (KitProg3_MiniProg4) configuration in the Quick Panel. For details, see the "Program and debug" section in the Eclipse IDE for ModusToolbox™ user guide.

In other IDEs

Follow the instructions in your preferred IDE.

Design and implementation

Overview

The overcurrent detection (OCD) is a hardware safety mechanism in the PACSS block that provides fast detection of overcurrent conditions. Unlike software-based current monitoring through ADC sampling, the OCD operates independently and continuously, enabling rapid response to potentially dangerous current levels in battery management applications.

OCD architecture

The OCD monitors the differential voltage across the current sense inputs (RSH0/RSL0) and compares it against a programmable threshold. The OCD includes:

Positive comparator: Detects when the differential voltage exceeds the positive threshold (discharge overcurrent)
Negative comparator: Detects when the differential voltage exceeds the negative threshold (charge overcurrent)
Glitch filter: Filters out transient spikes to prevent false triggers
OCD output: Asserted when the glitch filter count exceeds the configured limit

Figure 2. Software flowchart
The application initializes the OCD using the Cy_DSADC_OcdInit() function with the configuration from the Device Configurator. The configuration includes threshold level, glitch filter mode, clock division, and comparator enable settings

After initialization, the OCD configuration is read back using the Cy_DSADC_OcdGetConfig() function to verify correct setup. The output mode is set using the Cy_DSADC_OcdSetOutputMode() function before enabling the OCD with the Cy_DSADC_OcdEnable() function

OCD interrupts are configured to handle three types of events:
- Unfiltered interrupt: Generated immediately when the OCD threshold is exceeded, before glitch filtering. Useful for monitoring transient events
- Trigger interrupt: Generated when the glitch filter count reaches the positive or negative limit. Indicates a sustained overcurrent condition
- Fault interrupt: Generated when an OCD operation error occurs

The ADC conversion is started in parallel using the Cy_DSADC_StartConversionAchan() function to measure the actual current through the shunt resistor. The ADC result is displayed alongside the OCD status

In the main loop, the application continuously monitors:
- ADC measurement results (input voltage and calculated current)
- Glitch filter counter value
- Positive and negative comparator status
- OCD interrupt flags (Trigger, Unfiltered, Fault)

OCD configuration parameters

Table 1. OCD configuration parameters

Parameter	Default value	Description
OCD Threshold	37.5 mV	Differential voltage threshold for overcurrent detection
Positive Limit	500	Glitch filter count limit for discharge overcurrent
Negative Limit	500	Glitch filter count limit for charge overcurrent
Glitch Filter Mode	Continuous	Filter mode (Continuous or Single-shot)
Clock Division	/2	OCD sampling clock divider

Resources and settings

Table 2. Application resources

Resource	Alias/object	Purpose
UART	CYBSP_UART	UART object used for monitoring OCD status on terminal
PACSS	PACSS	ADC to measure shunt voltage and OCD for overcurrent detection
OCD	OCD0	Overcurrent detector instance for monitoring current

Related resources

Resources	Links
Application notes	AN230264 – Getting started with PSOC™ HVPA family AN230370 – Precision analog channel subsystem in PSOC™ 4 HVPA family AN0034 – Getting started with PSOC™ 4 HVMS and PSOC™ 4 HVPA MCUs in ModusToolbox™
Code examples	Using ModusToolbox™ on GitHub
Device documentation	PSOC™ 4 HVPA datasheets PSOC™ 4 HVPA MCU reference manuals
Development kits	Select your kits from the Evaluation board finder
Libraries on GitHub	mtb-pdl-cat2 – PSOC™ 4 Peripheral Driver Library (PDL) mtb-hal-cat2 – Hardware Abstraction Layer (HAL) library
Tools	ModusToolbox™ – ModusToolbox™ software is a collection of easy-to-use libraries and tools enabling rapid development with Infineon MCUs for applications ranging from wireless and cloud-connected systems, edge AI/ML, embedded sense and control, to wired USB connectivity using PSOC™ Industrial/IoT MCUs, AIROC™ Wi-Fi and Bluetooth® connectivity devices, XMC™ Industrial MCUs, and EZ-USB™/EZ-PD™ wired connectivity controllers. ModusToolbox™ incorporates a comprehensive set of BSPs, HAL, libraries, configuration tools, and provides support for industry-standard IDEs to fast-track your embedded application development

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

Document history

Document title: CE242826 – PSOC™ 4 HV: PACSS OCD

Version	Description of change
1.0.0	New code example

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License

Infineon/mtb-example-ce242826-pacss-ocd

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