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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 QNX Neutrino 7.1.
Sensor Framework
Sensor Framework Libraries
Sensor Developer's Guide
The Sensor library abstracts the complexity of interfacing with sensors and cameras connected to the target board.
Sensor Library Reference
The Sensor library provides applications with a consistent interface to interact with sensors connected to the system.
sensor_api.h
The definitions, data types, and functions to access sensors, receive and store data from them, and handle sensor events.
sensor_roll_close_file()
Close the file descriptor for a file on the sensor roll

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics 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 QNX Neutrino 7.1.
- Quickstart Guide
- OS Components & Operations
- Audio & Graphics API
- Multimedia
- Networking Middleware
- Programming
- Sensor Framework
  - Architecture
  - Getting Started
    This guide gets you started with the Sensor Framework for QNX SDP.
  - Sensor Framework Libraries
    - ADAS Library Developer's Guide
      The ADAS library facilitates the development of embedded systems that rely on sensor data.
    - Camera Developer's Guide
      The Camera library abstracts the complexity of interfacing with a camera connected to the target board.
    - Sensor Developer's Guide
      The Sensor library abstracts the complexity of interfacing with sensors and cameras connected to the target board.
      - Sensor Library Overview
        The Sensor library provides applications with a consistent interface to simultaneously access up to 64 sensors connected to the hardware platform.
      - Opening and closing a connection to a sensor unit
        Applications use a handle provided through the Sensor API to access each of the logical sensor units that are configured in the sensor configuration file.
      - Starting and stopping a sensor unit
      - Opening and closing a connection to an interim data unit
        Applications use a handle provided through the Sensor API to access each of the interim data units that are configured in the interim data configuration file.
      - Starting an interim data unit
      - Accessing sensor data and status
        Applications can access the sensor's data and status by binding callback functions or events that are of the structure sigevent to sensor events that are of particular interest.
      - Publishing interim data
        Publishers are applications that generate interim data information for other applications.
      - Subscribing to interim data
        Subscribers are applications that use interim data that publishers generate.
      - Recording data from a sensor
        Applications can record the data that's streaming from a sensor to a file.
      - Querying sensor information
      - Using external clocks
        Sensor timestamps can be based on a reference time provided by an external clock library.
      - Using external sensor drivers
        Sensors that aren't already supported by the Sensor Framework for QNX SDP can be provided by an external sensor driver library.
      - Sensor Library Reference
        The Sensor library provides applications with a consistent interface to interact with sensors connected to the system.
        sensor_api.h
        The definitions, data types, and functions to access sensors, receive and store data from them, and handle sensor events.
        Definitions in sensor_api.h
        Preprocessor macro definitions for the sensor_api.h header file in the libsensor library
        sensor_access_mode_t
        Available access modes
        sensor_bayerformat_t
        Bayer array macro-pixel format
        sensor_bayerjustify_t
        Bayer bit justification
        sensor_buffer_t
        Content of a data buffer
        sensor_close()
        Discontinue using a logical sensor on the device
        sensor_coord_system_t
        Coordinate transforms
        sensor_data_callback_t
        Callback function that receives data
        sensor_devstatus_t
        Status of the sensor device
        sensor_disable_data_callback()
        Disable a data callback
        sensor_disable_event()
        Disable a registered event
        sensor_disable_status_callback()
        Disable a status callback
        sensor_enable_event()
        Register a sigevent to be signaled when an event occurs
        sensor_error_t
        Error codes for the Sensor library
        sensor_event_t
        Sensor events that you can register
        sensor_eventkey_t
        Sensor event key that indicates an event is enabled
        sensor_eventmode_t
        Event buffering modes
        sensor_feed_input_metadata()
        Feed metadata to a sensor
        sensor_format_t
        Format of the data in a sensor buffer
        sensor_format_data_t
        Format for sensor data with payload consisting of format-specific structures
        sensor_format_info_t
        Union containing all available frame descriptors for the Sensor library
        sensor_format_unspecified_t
        Format to represent data when the format is unknown
        sensor_format_user_data_t
        Format for user data published as interim sensor data
        sensor_format_video_bayer_t
        Format for all Bayer video formats
        sensor_format_video_cbycry_t
        Format for a YCbCr 4:2:2 packed frame type
        sensor_format_video_compressed_t
        Format for compressed video frames
        sensor_format_video_packed_t
        Format for all packed video formats
        sensor_format_video_planar_t
        Format for all planar video formats
        sensor_format_video_roi_t
        Format for a region-of-interest (ROI) video data
        sensor_format_video_semiplanar_t
        Format for semi-planar video
        sensor_get_buffer()
        Retrieve a data buffer for an event that was signaled
        sensor_get_location_property()
        Retrieve one or more location properties for a sensor
        sensor_get_metadata_limits()
        Retrieve limit values for a metadata type
        sensor_get_physical_property()
        Retrieve one or more physical properties of the sensor
        sensor_get_screen_buffer()
        Retrieve the Screen buffer associated with a sensor buffer
        sensor_get_status_details()
        Retrieve the status details from a status event
        sensor_get_streaming_property()
        Retrieve one or more streaming properties of the sensor
        sensor_get_supported_sensors()
        Retrieve an enumerated list of sensors available on the device
        sensor_get_unit()
        Retrieve the sensor unit associated with a sensor handle
        sensor_handle_t
        Pointer type representing a handle for an open instance of a sensor unit
        sensor_input_metadata_t
        Data structure describing metadata provided by a client to a sensor
        sensor_location_prop_t
        Sensor location properties
        sensor_metadata_limits_t
        Limit values for a metadata type supported by a sensor
        sensor_metadata_type_t
        Sensor metadata types
        sensor_open()
        Request a handle to access a logical sensor unit
        sensor_physprop_t
        Sensor physical properties
        sensor_playback_group_t
        Sensor playback groups
        sensor_register_data_callback()
        Register a data callback for a specified event
        sensor_register_status_callback()
        Register a status callback for an event
        sensor_return_buffer()
        Return the memory for a data buffer that was retrieved
        sensor_roll_close_file()
        Close the file descriptor for a file on the sensor roll
        sensor_roll_format_t
        Sensor formats used by sensor roll files
        sensor_roll_get_path()
        Retrieve the sensor roll path
        sensor_roll_open_file()
        Create and open the next available file on the sensor roll for writing
        sensor_roll_set_filename_suffix()
        Set the suffix to add to filenames generated from the sensor roll
        sensor_roll_set_path()
        Set the sensor roll path
        sensor_speed_metadata_t
        Sensor speed metadata structure
        sensor_speed_metadata_limits_t
        Sensor speed metadata limit values structure
        sensor_speed_yaw_metadata_t
        Sensor speed and yaw rate metadata structure
        sensor_speed_yaw_metadata_limits_t
        Sensor speed and yaw rate metadata limit values structure
        sensor_start()
        Start streaming data from a sensor
        sensor_start_recording()
        Start recording sensor data to a file
        sensor_status_callback_t
        Prototype for a callback function that receives sensor status updates
        sensor_stop()
        Stop streaming data from a sensor
        sensor_stop_recording()
        Stop recording sensor data
        sensor_streamprop_t
        Sensor streaming properties
        sensor_type_t
        Supported sensor types
        sensor_unit_t
        Sensor units on the device
        sensor_vehicle_direction_t
        Host vehicle direction
        sensor_videocodec_t
        Video compression formats used by the video encoder
        supported_sensor_info_t
        Information associated with a sensor
        sensor_gps_imu.h
        The definitions of the data formats for GPS and IMU sensors.
        sensor_interim_data.h
        The definitions and functions to work with interim data.
        sensor_lidar.h
        The definitions of the data formats for lidar sensors.
        sensor_radar.h
        The definitions of the data formats for radar sensors.
        external_sensor_api.h
        The definitions and functions to use the External Sensor library.
      - Glossary
        This is a list of terms commonly used in the context of the Sensor library.
  - Sensor Framework Services
- System Security Guide
  The QNX System Security Guide is intended for both system integrators who are responsible for the security of a QNX Neutrino RTOS system and developers who want to create a QNX Neutrino resource manager free from vulnerabilities.
- Utilities & Libraries
QNX Hypervisor
The QNX Hypervisor allows 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.
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 Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

sensor_roll_close_file()

Close the file descriptor for a file on the sensor roll

Synopsis:

#include <sensor/sensor_api.h>

sensor_error_t sensor_roll_close_file(int fd)

Arguments:

fd: The file descriptor to close.

Library:

libsensor

Description:

The sensor roll is a directory on the device where the Sensor library saves files. Use this function to close the file descriptor that was returned for one of these files by calling sensor_roll_open_file().

Returns:

SENSOR_EOK when the function successfully completes, otherwise another sensor_error_t value that provides the reason that the call failed.

Page updated: March 12, 2026