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QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
Utilities & Libraries
GPIO Framework
GPIO client functions (gpio_api.h)
gpio_get_fsel()
Get the GPIO function select value

QNX Momentics IDE User's Guide
This User's Guide describes version 8.0 of the Integrated Development Environment (IDE) that's part of the QNX Tool Suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running the QNX OS 8.0.
- Quickstart Guide
- System Architecture
  The System Architecture guide accompanies the QNX OS and is intended for both application developers and end-users.
- OS Components & Operations
- Graphics
- Programming
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX OS system and developers who want to create a QNX OS resource manager free from vulnerabilities.
- Utilities & Libraries
  - C Library Reference
  - Devctl and Ioctl Commands
  - Introspection API Reference
  - JSON Library Reference
  - PAM Reference
  - QNX Helpers Developer's Guide
    These libraries provide QNX helpers, including helpers that assist with logging, string conversion, and number and type sizes.
  - SPI Framework Technote
  - GPIO Framework
    - Interfacing GPIO hardware modules
    - GPIO client functions (gpio_api.h)
      - gpio_close()
        Close a GPIO device
      - gpio_custom()
        Perform a custom GPIO operation
      - gpio_get_debounce()
        Get the GPIO debounce
      - gpio_get_dir()
        Get the GPIO direction
      - gpio_get_enable()
        Get the GPIO enable state
      - gpio_get_fsel()
        Get the GPIO function select value
      - gpio_get_info()
        Get the GPIO information of a pin
      - gpio_get_itype()
        Get the GPIO interrupt trigger type
      - gpio_get_level()
        Get the GPIO level
      - gpio_get_pull()
        Get the GPIO pull configuration
      - gpio_open()
        Open a GPIO device
      - gpio_set_debounce()
        Set the GPIO debounce
      - gpio_set_dir()
        Set the GPIO direction
      - gpio_set_enable()
        Set the GPIO enable state
      - gpio_set_itype()
        Set the GPIO interrupt trigger type
      - gpio_set_level()
        Set the GPIO level
      - gpio_set_pull()
        Set the GPIO pull configuration
    - GPIO hardware module functions (gpio_hw.h)
  - QNX Cryptography Library
    The QNX Cryptography Library (qcrypto) is a flexible cryptography framework that allows you to choose which cryptography provider responds to requests on a per-process basis.
  - QNX devcrypto Service
  - Utilities Reference
  - WPA Control Interface Reference
    This document provides a reference for the Wi-Fi Protected Access (WPA) control interface, which provides a C API for the WPA/IEEE 802.11i protocols in Wi-Fi client stations. Application developers who want to control WPA operations and get associated status and event data should read this reference.
- Migrating to QNX OS 8.0
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Toolkit for Visual Studio Code
This User's Guide describes the QNX^® Toolkit for Visual Studio Code. The guide introduces you to the QNX Toolkit by explaining the QNX development environment and how to build, run, and debug your QNX^® Operating System (OS) applications and systems.
QNX Hypervisor and QNX Hypervisor for Safety
The QNX Hypervisor and QNX Hypervisor for Safety products allow you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation, explains how to obtain technical support, and provides some information about licensing.

gpio_get_fsel()

Get the GPIO function select value

Synopsis:

#include <hw/gpio_api.h>

gpio_itype_t gpio_get_fsel( int32_t gpio_fd,
                            gpio_header_t hdr );

Arguments:

gpio_fd: The file descriptor of a GPIO device.
hdr: The GPIO header identifying a GPIO pin.

Description:

The gpio_get_fsel() function gets the GPIO function select value of a pin.

Returns:

A valid GPIO function select value on success, or -1 if an error occurs (errno is set).

Errors:

Any error value that MsgSend() can return.

Page updated: June 11, 2026