Macros
#define	HID_API_VERSION_MAJOR 0
	Static/compile-time major version of the library.

#define	HID_API_VERSION_MINOR 15
	Static/compile-time minor version of the library.

#define	HID_API_VERSION_PATCH 0
	Static/compile-time patch version of the library.

#define	HID_API_MAKE_VERSION(mj, mn, p) (((mj) << 24) \| ((mn) << 8) \| (p))
	Coverts a version as Major/Minor/Patch into a number: <8 bit major><16 bit minor><8 bit patch>.

#define	HID_API_VERSION HID_API_MAKE_VERSION(HID_API_VERSION_MAJOR, HID_API_VERSION_MINOR, HID_API_VERSION_PATCH)
	Static/compile-time version of the library.

#define	HID_API_VERSION_STR HID_API_TO_VERSION_STR(HID_API_VERSION_MAJOR, HID_API_VERSION_MINOR, HID_API_VERSION_PATCH)
	Static/compile-time string version of the library.

#define	HID_API_MAX_REPORT_DESCRIPTOR_SIZE 4096
	Maximum expected HID Report descriptor size in bytes.

Enumerations
enum	hid_bus_type { HID_API_BUS_UNKNOWN = 0x00 , HID_API_BUS_USB = 0x01 , HID_API_BUS_BLUETOOTH = 0x02 , HID_API_BUS_I2C = 0x03 , HID_API_BUS_SPI = 0x04 }
	HID underlying bus types. More...

Functions
int HID_API_EXPORT HID_API_CALL	hid_init (void)
	Initialize the HIDAPI library.

int HID_API_EXPORT HID_API_CALL	hid_exit (void)
	Finalize the HIDAPI library.

struct hid_device_info HID_API_EXPORT *HID_API_CALL	hid_enumerate (unsigned short vendor_id, unsigned short product_id)
	Enumerate the HID Devices.

void HID_API_EXPORT HID_API_CALL	hid_free_enumeration (struct hid_device_info *devs)
	Free an enumeration Linked List.

HID_API_EXPORT hid_device *HID_API_CALL	hid_open (unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number)
	Open a HID device using a Vendor ID (VID), Product ID (PID) and optionally a serial number.

HID_API_EXPORT hid_device *HID_API_CALL	hid_open_path (const char *path)
	Open a HID device by its path name.

int HID_API_EXPORT HID_API_CALL	hid_write (hid_device dev, const unsigned char data, size_t length)
	Write an Output report to a HID device.

int HID_API_EXPORT HID_API_CALL	hid_read_timeout (hid_device dev, unsigned char data, size_t length, int milliseconds)
	Read an Input report from a HID device with timeout.

int HID_API_EXPORT HID_API_CALL	hid_read (hid_device dev, unsigned char data, size_t length)
	Read an Input report from a HID device.

int HID_API_EXPORT HID_API_CALL	hid_set_nonblocking (hid_device *dev, int nonblock)
	Set the device handle to be non-blocking.

int HID_API_EXPORT HID_API_CALL	hid_send_feature_report (hid_device dev, const unsigned char data, size_t length)
	Send a Feature report to the device.

int HID_API_EXPORT HID_API_CALL	hid_get_feature_report (hid_device dev, unsigned char data, size_t length)
	Get a feature report from a HID device.

int HID_API_EXPORT HID_API_CALL	hid_send_output_report (hid_device dev, const unsigned char data, size_t length)
	Send a Output report to the device.

int HID_API_EXPORT HID_API_CALL	hid_get_input_report (hid_device dev, unsigned char data, size_t length)
	Get a input report from a HID device.

void HID_API_EXPORT HID_API_CALL	hid_close (hid_device *dev)
	Close a HID device.

int HID_API_EXPORT_CALL	hid_get_manufacturer_string (hid_device dev, wchar_t string, size_t maxlen)
	Get The Manufacturer String from a HID device.

int HID_API_EXPORT_CALL	hid_get_product_string (hid_device dev, wchar_t string, size_t maxlen)
	Get The Product String from a HID device.

int HID_API_EXPORT_CALL	hid_get_serial_number_string (hid_device dev, wchar_t string, size_t maxlen)
	Get The Serial Number String from a HID device.

struct hid_device_info HID_API_EXPORT *HID_API_CALL	hid_get_device_info (hid_device *dev)
	Get The struct hid_device_info from a HID device.

int HID_API_EXPORT_CALL	hid_get_indexed_string (hid_device dev, int string_index, wchar_t string, size_t maxlen)
	Get a string from a HID device, based on its string index.

int HID_API_EXPORT_CALL	hid_get_report_descriptor (hid_device dev, unsigned char buf, size_t buf_size)
	Get a report descriptor from a HID device.

HID_API_EXPORT const wchar_t *HID_API_CALL	hid_error (hid_device *dev)
	Get a string describing the last error which occurred.

HID_API_EXPORT const struct hid_api_version *HID_API_CALL	hid_version (void)
	Get a runtime version of the library.

HID_API_EXPORT const char *HID_API_CALL	hid_version_str (void)
	Get a runtime version string of the library.

Detailed Description

Macro Definition Documentation

◆ HID_API_MAKE_VERSION

#define HID_API_MAKE_VERSION	(	mj,
		mn,
		p
	)	(((mj) << 24) \| ((mn) << 8) \| (p))

Coverts a version as Major/Minor/Patch into a number: <8 bit major><16 bit minor><8 bit patch>.

This macro was added in version 0.12.0.

Convenient function to be used for compile-time checks, like:

#if HID_API_VERSION >= HID_API_MAKE_VERSION(0, 12, 0)

Examples: test.c.

◆ HID_API_MAX_REPORT_DESCRIPTOR_SIZE

#define HID_API_MAX_REPORT_DESCRIPTOR_SIZE 4096

Maximum expected HID Report descriptor size in bytes.

Since version 0.13.0, HID_API_VERSION >= HID_API_MAKE_VERSION(0, 13, 0)

Examples: test.c.

◆ HID_API_VERSION

#define HID_API_VERSION HID_API_MAKE_VERSION(HID_API_VERSION_MAJOR, HID_API_VERSION_MINOR, HID_API_VERSION_PATCH)

Static/compile-time version of the library.

This macro was added in version 0.12.0.

See also: HID_API_MAKE_VERSION.

Examples: test.c.

◆ HID_API_VERSION_MAJOR

#define HID_API_VERSION_MAJOR 0

Static/compile-time major version of the library.

◆ HID_API_VERSION_MINOR

#define HID_API_VERSION_MINOR 15

Static/compile-time minor version of the library.

◆ HID_API_VERSION_PATCH

#define HID_API_VERSION_PATCH 0

Static/compile-time patch version of the library.

◆ HID_API_VERSION_STR

#define HID_API_VERSION_STR HID_API_TO_VERSION_STR(HID_API_VERSION_MAJOR, HID_API_VERSION_MINOR, HID_API_VERSION_PATCH)

Static/compile-time string version of the library.

Examples: test.c.

Enumeration Type Documentation

◆ hid_bus_type

enum hid_bus_type

HID underlying bus types.

Enumerator
HID_API_BUS_UNKNOWN	Unknown bus type
HID_API_BUS_USB	USB bus Specifications: https://usb.org/hid
HID_API_BUS_BLUETOOTH	Bluetooth or Bluetooth LE bus Specifications: https://www.bluetooth.com/specifications/specs/human-interface-device-profile-1-1-1/ https://www.bluetooth.com/specifications/specs/hid-service-1-0/ https://www.bluetooth.com/specifications/specs/hid-over-gatt-profile-1-0/
HID_API_BUS_I2C	I2C bus Specifications: https://docs.microsoft.com/previous-versions/windows/hardware/design/dn642101(v=vs.85)
HID_API_BUS_SPI	SPI bus Specifications: https://www.microsoft.com/download/details.aspx?id=103325

Function Documentation

◆ hid_close()

void HID_API_EXPORT HID_API_CALL hid_close ( hid_device * dev )

Close a HID device.

Parameters

dev	A device handle returned from hid_open().

Examples: test.c.

◆ hid_enumerate()

struct hid_device_info HID_API_EXPORT *HID_API_CALL hid_enumerate	(	unsigned short	vendor_id,
		unsigned short	product_id
	)

Enumerate the HID Devices.

This function returns a linked list of all the HID devices attached to the system which match vendor_id and product_id. If vendor_id is set to 0 then any vendor matches. If product_id is set to 0 then any product matches. If vendor_id and product_id are both set to 0, then all HID devices will be returned.

Parameters

vendor_id	The Vendor ID (VID) of the types of device to open.
product_id	The Product ID (PID) of the types of device to open.

Returns: This function returns a pointer to a linked list of type struct hid_device_info, containing information about the HID devices attached to the system, or NULL in the case of failure or if no HID devices present in the system. Call hid_error(NULL) to get the failure reason.

Note: The returned value by this function must to be freed by calling hid_free_enumeration(), when not needed anymore.

Examples: test.c.

◆ hid_error()

HID_API_EXPORT const wchar_t *HID_API_CALL hid_error ( hid_device * dev )

Get a string describing the last error which occurred.

This function is intended for logging/debugging purposes.

This function guarantees to never return NULL. If there was no error in the last function call - the returned string clearly indicates that.

Any HIDAPI function that can explicitly indicate an execution failure (e.g. by an error code, or by returning NULL) - may set the error string, to be returned by this function.

Strings returned from hid_error() must not be freed by the user, i.e. owned by HIDAPI library. Device-specific error string may remain allocated at most until hid_close() is called. Global error string may remain allocated at most until hid_exit() is called.

Parameters

dev	A device handle returned from hid_open(), or NULL to get the last non-device-specific error (e.g. for errors in hid_open() or hid_enumerate()).

Returns: A string describing the last error (if any).

Examples: test.c.

◆ hid_exit()

int HID_API_EXPORT HID_API_CALL hid_exit ( void )

Finalize the HIDAPI library.

This function frees all of the static data associated with HIDAPI. It should be called at the end of execution to avoid memory leaks.

Returns: This function returns 0 on success and -1 on error.

Examples: test.c.

◆ hid_free_enumeration()

void HID_API_EXPORT HID_API_CALL hid_free_enumeration ( struct hid_device_info * devs )

Free an enumeration Linked List.

This function frees a linked list created by hid_enumerate().

Parameters

devs	Pointer to a list of struct_device returned from hid_enumerate().

Examples: test.c.

◆ hid_get_device_info()

struct hid_device_info HID_API_EXPORT *HID_API_CALL hid_get_device_info ( hid_device * dev )

Get The struct hid_device_info from a HID device.

Since version 0.13.0, HID_API_VERSION >= HID_API_MAKE_VERSION(0, 13, 0)

Parameters

dev	A device handle returned from hid_open().

Returns: This function returns a pointer to the struct hid_device_info for this hid_device, or NULL in the case of failure. Call hid_error(dev) to get the failure reason. This struct is valid until the device is closed with hid_close().

Note: The returned object is owned by the dev, and SHOULD NOT be freed by the user.

Examples: test.c.

◆ hid_get_feature_report()

int HID_API_EXPORT HID_API_CALL hid_get_feature_report	(	hid_device *	dev,
		unsigned char *	data,
		size_t	length
	)

Get a feature report from a HID device.

Set the first byte of data[] to the Report ID of the report to be read. Make sure to allow space for this extra byte in data[]. Upon return, the first byte will still contain the Report ID, and the report data will start in data[1].

Parameters

dev	A device handle returned from hid_open().
data	A buffer to put the read data into, including the Report ID. Set the first byte of `data`[] to the Report ID of the report to be read, or set it to zero if your device does not use numbered reports.
length	The number of bytes to read, including an extra byte for the report ID. The buffer can be longer than the actual report.

Returns: This function returns the number of bytes read plus one for the report ID (which is still in the first byte), or -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_get_indexed_string()

int HID_API_EXPORT_CALL hid_get_indexed_string	(	hid_device *	dev,
		int	string_index,
		wchar_t *	string,
		size_t	maxlen
	)

Get a string from a HID device, based on its string index.

Parameters

dev	A device handle returned from hid_open().
string_index	The index of the string to get.
string	A wide string buffer to put the data into.
maxlen	The length of the buffer in multiples of wchar_t.

Returns: This function returns 0 on success and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_get_input_report()

int HID_API_EXPORT HID_API_CALL hid_get_input_report	(	hid_device *	dev,
		unsigned char *	data,
		size_t	length
	)

Get a input report from a HID device.

Since version 0.10.0, HID_API_VERSION >= HID_API_MAKE_VERSION(0, 10, 0)

Set the first byte of data[] to the Report ID of the report to be read. Make sure to allow space for this extra byte in data[]. Upon return, the first byte will still contain the Report ID, and the report data will start in data[1].

Parameters

dev	A device handle returned from hid_open().
data	A buffer to put the read data into, including the Report ID. Set the first byte of `data`[] to the Report ID of the report to be read, or set it to zero if your device does not use numbered reports.
length	The number of bytes to read, including an extra byte for the report ID. The buffer can be longer than the actual report.

Returns: This function returns the number of bytes read plus one for the report ID (which is still in the first byte), or -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_get_manufacturer_string()

int HID_API_EXPORT_CALL hid_get_manufacturer_string	(	hid_device *	dev,
		wchar_t *	string,
		size_t	maxlen
	)

Get The Manufacturer String from a HID device.

Parameters

dev	A device handle returned from hid_open().
string	A wide string buffer to put the data into.
maxlen	The length of the buffer in multiples of wchar_t.

Returns: This function returns 0 on success and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_get_product_string()

int HID_API_EXPORT_CALL hid_get_product_string	(	hid_device *	dev,
		wchar_t *	string,
		size_t	maxlen
	)

Get The Product String from a HID device.

Parameters

dev	A device handle returned from hid_open().
string	A wide string buffer to put the data into.
maxlen	The length of the buffer in multiples of wchar_t.

Returns: This function returns 0 on success and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_get_report_descriptor()

int HID_API_EXPORT_CALL hid_get_report_descriptor	(	hid_device *	dev,
		unsigned char *	buf,
		size_t	buf_size
	)

Get a report descriptor from a HID device.

Since version 0.14.0, HID_API_VERSION >= HID_API_MAKE_VERSION(0, 14, 0)

User has to provide a preallocated buffer where descriptor will be copied to. The recommended size for preallocated buffer is HID_API_MAX_REPORT_DESCRIPTOR_SIZE bytes.

Parameters

dev	A device handle returned from hid_open().
buf	The buffer to copy descriptor into.
buf_size	The size of the buffer in bytes.

Returns: This function returns non-negative number of bytes actually copied, or -1 on error.

Examples: test.c.

◆ hid_get_serial_number_string()

int HID_API_EXPORT_CALL hid_get_serial_number_string	(	hid_device *	dev,
		wchar_t *	string,
		size_t	maxlen
	)

Get The Serial Number String from a HID device.

Parameters

dev	A device handle returned from hid_open().
string	A wide string buffer to put the data into.
maxlen	The length of the buffer in multiples of wchar_t.

Returns: This function returns 0 on success and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_init()

int HID_API_EXPORT HID_API_CALL hid_init ( void )

Initialize the HIDAPI library.

This function initializes the HIDAPI library. Calling it is not strictly necessary, as it will be called automatically by hid_enumerate() and any of the hid_open_*() functions if it is needed. This function should be called at the beginning of execution however, if there is a chance of HIDAPI handles being opened by different threads simultaneously.

Returns: This function returns 0 on success and -1 on error. Call hid_error(NULL) to get the failure reason.

Examples: test.c.

◆ hid_open()

HID_API_EXPORT hid_device *HID_API_CALL hid_open	(	unsigned short	vendor_id,
		unsigned short	product_id,
		const wchar_t *	serial_number
	)

Open a HID device using a Vendor ID (VID), Product ID (PID) and optionally a serial number.

If serial_number is NULL, the first device with the specified VID and PID is opened.

Parameters

vendor_id	The Vendor ID (VID) of the device to open.
product_id	The Product ID (PID) of the device to open.
serial_number	The Serial Number of the device to open (Optionally NULL).

Returns: This function returns a pointer to a hid_device object on success or NULL on failure. Call hid_error(NULL) to get the failure reason.

Note: The returned object must be freed by calling hid_close(), when not needed anymore.

Examples: test.c.

◆ hid_open_path()

HID_API_EXPORT hid_device *HID_API_CALL hid_open_path ( const char * path )

Open a HID device by its path name.

The path name be determined by calling hid_enumerate(), or a platform-specific path name can be used (eg: /dev/hidraw0 on Linux).

Parameters

path	The path name of the device to open

Returns: This function returns a pointer to a hid_device object on success or NULL on failure. Call hid_error(NULL) to get the failure reason.

Note: The returned object must be freed by calling hid_close(), when not needed anymore.

Examples: test.c.

◆ hid_read()

int HID_API_EXPORT HID_API_CALL hid_read	(	hid_device *	dev,
		unsigned char *	data,
		size_t	length
	)

Read an Input report from a HID device.

Input reports are returned to the host through the INTERRUPT IN endpoint. The first byte will contain the Report number if the device uses numbered reports.

Parameters

dev	A device handle returned from hid_open().
data	A buffer to put the read data into.
length	The number of bytes to read. For devices with multiple reports, make sure to read an extra byte for the report number.

Returns: This function returns the actual number of bytes read and -1 on error. Call hid_error(dev) to get the failure reason. If no packet was available to be read and the handle is in non-blocking mode, this function returns 0.

Examples: test.c.

◆ hid_read_timeout()

int HID_API_EXPORT HID_API_CALL hid_read_timeout	(	hid_device *	dev,
		unsigned char *	data,
		size_t	length,
		int	milliseconds
	)

Read an Input report from a HID device with timeout.

Input reports are returned to the host through the INTERRUPT IN endpoint. The first byte will contain the Report number if the device uses numbered reports.

Parameters

dev	A device handle returned from hid_open().
data	A buffer to put the read data into.
length	The number of bytes to read. For devices with multiple reports, make sure to read an extra byte for the report number.
milliseconds	timeout in milliseconds or -1 for blocking wait.

Returns: This function returns the actual number of bytes read and -1 on error. Call hid_error(dev) to get the failure reason. If no packet was available to be read within the timeout period, this function returns 0.

Examples: test.c.

◆ hid_send_feature_report()

int HID_API_EXPORT HID_API_CALL hid_send_feature_report	(	hid_device *	dev,
		const unsigned char *	data,
		size_t	length
	)

Send a Feature report to the device.

Feature reports are sent over the Control endpoint as a Set_Report transfer. The first byte of data[] must contain the Report ID. For devices which only support a single report, this must be set to 0x0. The remaining bytes contain the report data. Since the Report ID is mandatory, calls to hid_send_feature_report() will always contain one more byte than the report contains. For example, if a hid report is 16 bytes long, 17 bytes must be passed to hid_send_feature_report(): the Report ID (or 0x0, for devices which do not use numbered reports), followed by the report data (16 bytes). In this example, the length passed in would be 17.

Parameters

dev	A device handle returned from hid_open().
data	The data to send, including the report number as the first byte.
length	The length in bytes of the data to send, including the report number.

Returns: This function returns the actual number of bytes written and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_send_output_report()

int HID_API_EXPORT HID_API_CALL hid_send_output_report	(	hid_device *	dev,
		const unsigned char *	data,
		size_t	length
	)

Send a Output report to the device.

Since version 0.15.0, HID_API_VERSION >= HID_API_MAKE_VERSION(0, 15, 0)

Output reports are sent over the Control endpoint as a Set_Report transfer. The first byte of data[] must contain the Report ID. For devices which only support a single report, this must be set to 0x0. The remaining bytes contain the report data. Since the Report ID is mandatory, calls to hid_send_output_report() will always contain one more byte than the report contains. For example, if a hid report is 16 bytes long, 17 bytes must be passed to hid_send_output_report(): the Report ID (or 0x0, for devices which do not use numbered reports), followed by the report data (16 bytes). In this example, the length passed in would be 17.

This function sets the return value of hid_error().

Parameters

dev	A device handle returned from hid_open().
data	The data to send, including the report number as the first byte.
length	The length in bytes of the data to send, including the report number.

Returns: This function returns the actual number of bytes written and -1 on error.

See also: hid_write

Examples: test.c.

◆ hid_set_nonblocking()

int HID_API_EXPORT HID_API_CALL hid_set_nonblocking	(	hid_device *	dev,
		int	nonblock
	)

Set the device handle to be non-blocking.

In non-blocking mode calls to hid_read() will return immediately with a value of 0 if there is no data to be read. In blocking mode, hid_read() will wait (block) until there is data to read before returning.

Nonblocking can be turned on and off at any time.

Parameters

dev	A device handle returned from hid_open().
nonblock	enable or not the nonblocking reads 1 to enable nonblocking 0 to disable nonblocking.

Returns: This function returns 0 on success and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

◆ hid_version()

HID_API_EXPORT const struct hid_api_version *HID_API_CALL hid_version ( void )

Get a runtime version of the library.

This function is thread-safe.

Returns: Pointer to statically allocated struct, that contains version.

Examples: test.c.

◆ hid_version_str()

HID_API_EXPORT const char *HID_API_CALL hid_version_str ( void )

Get a runtime version string of the library.

This function is thread-safe.

Returns: Pointer to statically allocated string, that contains version string.

Examples: test.c.

◆ hid_write()

int HID_API_EXPORT HID_API_CALL hid_write	(	hid_device *	dev,
		const unsigned char *	data,
		size_t	length
	)

Write an Output report to a HID device.

The first byte of data[] must contain the Report ID. For devices which only support a single report, this must be set to 0x0. The remaining bytes contain the report data. Since the Report ID is mandatory, calls to hid_write() will always contain one more byte than the report contains. For example, if a hid report is 16 bytes long, 17 bytes must be passed to hid_write(), the Report ID (or 0x0, for devices with a single report), followed by the report data (16 bytes). In this example, the length passed in would be 17.

hid_write() will send the data on the first interrupt OUT endpoint, if one exists. If it does not the behaviour is as hid_send_output_report

Parameters

dev	A device handle returned from hid_open().
data	The data to send, including the report number as the first byte.
length	The length in bytes of the data to send.

Returns: This function returns the actual number of bytes written and -1 on error. Call hid_error(dev) to get the failure reason.

Examples: test.c.

Macros

Enumerations

Functions

Detailed Description

Macro Definition Documentation

◆ HID_API_MAKE_VERSION

◆ HID_API_MAX_REPORT_DESCRIPTOR_SIZE

◆ HID_API_VERSION

◆ HID_API_VERSION_MAJOR

◆ HID_API_VERSION_MINOR

◆ HID_API_VERSION_PATCH

◆ HID_API_VERSION_STR

Enumeration Type Documentation

◆ hid_bus_type

Function Documentation

◆ hid_close()

◆ hid_enumerate()

◆ hid_error()

◆ hid_exit()

◆ hid_free_enumeration()

◆ hid_get_device_info()

◆ hid_get_feature_report()

◆ hid_get_indexed_string()

◆ hid_get_input_report()

◆ hid_get_manufacturer_string()

◆ hid_get_product_string()

◆ hid_get_report_descriptor()

◆ hid_get_serial_number_string()

◆ hid_init()

◆ hid_open()

◆ hid_open_path()

◆ hid_read()

◆ hid_read_timeout()

◆ hid_send_feature_report()

◆ hid_send_output_report()

◆ hid_set_nonblocking()

◆ hid_version()

◆ hid_version_str()

◆ hid_write()