gpio_echo example

This example demonstrates use of the GPIO driver to verify the input/output functionality of GPIO pins and the operation of interrupts for GPIO pins.

Example directory in the SDK

The code of the example and build scripts are available at the following path:

/opt/KasperskyOS-Community-Edition-<platform>-<version>/examples/gpio_echo

List of programs

• Client – application that interacts with the GPIO driver.
• DCM – system program that lets you dynamically create IPC channels.

When you build an example for the target hardware platform, platform-specific drivers are automatically included in the solution:

• BSP is a hardware platform support package (Board Support Package). Provides cross-platform configuration of peripherals for the Radxa ROCK 3A and Raspberry Pi 4 B.
• GPIO – GPIO support driver for the Radxa ROCK 3A and Raspberry Pi 4 B.
• PinCtrl – low-level pin multiplexing (pinmux) configuration driver for the Radxa ROCK 3A.
• Bcm2711MboxArmToVc – driver for working with the VideoCore (VC6) coprocessor via mailbox technology for Raspberry Pi 4 B.

Initialization description

The solution initialization description file named init.yaml is generated during the solution build process based on the ./einit/src/init.yaml.in template. Macros in @INIT_*@‌ ‌format contained in the template are automatically expanded in the resulting init.yaml file. For more details, refer to init.yaml.in template.

Security policy description

The security policy description files for a KasperskyOS-based solution are located in the ./einit/src directory.

The security.psl file contains description of the solution security policy. This file is a top-level file into which a portion of the solution security policy description in the form of the PSL file dynld.psl is included via the use declaration. (The declarations in the PSL files are annotated to explain the purpose of these declarations.) The dynld.psl file contains the part of the security policy description that is used when dynamically linking the solution components.

Resources

The ./resources/xdl/gpio_echo directory contains the Client.edl file, which is the EDL description of the Client program.

Operating scenario

The Client program performs the following actions:

• Initializes drivers: BSP and GPIO. Opens the GPIO port with the name specified in the HW_MODULE_NAME macro.
• Configures GPIO pins:
  • The pin with the number specified in the GPIO_PIN_OUT macro is configured as an output pin.
  • The pin with the number specified in the GPIO_PIN_IN macro is configured as an input pin with interrupts enabled during the state transition (IN_MODE macro).
• Sets the output pin to a logical one state and verifies that an interrupt event was registered from the input pin. Verifies that the state of the input pin corresponds to a logical one.
• Sets the output pin to a logical zero state and checks whether an interrupt event was received from the input pin. Verifies that the state of the input pin corresponds to a logical zero.
• Closes the GPIO port, deinitializes drivers, and terminates with the EXIT_SUCCESS code if there are no errors.

Building and running the example

The CMake system, which is included with KasperskyOS Community Edition, is used to build and run the example.

For the gpio_echo example to work correctly, you must physically connect the output pin (the pin number is specified in the GPIO_PIN_OUT macro) to the input pin (GPIO_PIN_IN). This provides feedback so that a change in the state of an output pin triggers an interrupt event on the input pin.

See Building and running examples section.

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