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Functions
hidapi API

Functions

int HID_API_EXPORT HID_API_CALL hid_init (void)
 Initialize the HIDAPI library. More...
 
int HID_API_EXPORT HID_API_CALL hid_exit (void)
 Finalize the HIDAPI library. More...
 
struct hid_device_info
HID_API_EXPORT *HID_API_CALL 
hid_enumerate (unsigned short vendor_id, unsigned short product_id)
 Enumerate the HID Devices. More...
 
void HID_API_EXPORT HID_API_CALL hid_free_enumeration (struct hid_device_info *devs)
 Free an enumeration Linked List. More...
 
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. More...
 
HID_API_EXPORT hid_device
*HID_API_CALL 
hid_open_path (const char *path)
 Open a HID device by its path name. More...
 
int HID_API_EXPORT HID_API_CALL hid_write (hid_device *device, const unsigned char *data, size_t length)
 Write an Output report to a HID device. More...
 
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. More...
 
int HID_API_EXPORT HID_API_CALL hid_read (hid_device *device, unsigned char *data, size_t length)
 Read an Input report from a HID device. More...
 
int HID_API_EXPORT HID_API_CALL hid_set_nonblocking (hid_device *device, int nonblock)
 Set the device handle to be non-blocking. More...
 
int HID_API_EXPORT HID_API_CALL hid_send_feature_report (hid_device *device, const unsigned char *data, size_t length)
 Send a Feature report to the device. More...
 
int HID_API_EXPORT HID_API_CALL hid_get_feature_report (hid_device *device, unsigned char *data, size_t length)
 Get a feature report from a HID device. More...
 
void HID_API_EXPORT HID_API_CALL hid_close (hid_device *device)
 Close a HID device. More...
 
int HID_API_EXPORT_CALL hid_get_manufacturer_string (hid_device *device, wchar_t *string, size_t maxlen)
 Get The Manufacturer String from a HID device. More...
 
int HID_API_EXPORT_CALL hid_get_product_string (hid_device *device, wchar_t *string, size_t maxlen)
 Get The Product String from a HID device. More...
 
int HID_API_EXPORT_CALL hid_get_serial_number_string (hid_device *device, wchar_t *string, size_t maxlen)
 Get The Serial Number String from a HID device. More...
 
int HID_API_EXPORT_CALL hid_get_indexed_string (hid_device *device, int string_index, wchar_t *string, size_t maxlen)
 Get a string from a HID device, based on its string index. More...
 
HID_API_EXPORT const wchar_t
*HID_API_CALL 
hid_error (hid_device *device)
 Get a string describing the last error which occurred. More...
 

Detailed Description

Function Documentation

void HID_API_EXPORT HID_API_CALL hid_close ( hid_device device)

Close a HID device.

Parameters
deviceA device handle returned from hid_open().
struct hid_device_info HID_API_EXPORT* HID_API_CALL hid_enumerate ( unsigned short  vendor_id,
unsigned short  product_id 
)
read

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 @p vendor_id and @p product_id are both set to 0, then
all HID devices will be returned.
Parameters
vendor_idThe Vendor ID (VID) of the types of device to open.
product_idThe 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, containing information about the HID devices attached to the system, or NULL in the case of failure. Free this linked list by calling hid_free_enumeration().
HID_API_EXPORT const wchar_t* HID_API_CALL hid_error ( hid_device device)

Get a string describing the last error which occurred.

Parameters
deviceA device handle returned from hid_open().
Returns
This function returns a string containing the last error which occurred or NULL if none has occurred.
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.
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
devsPointer to a list of struct_device returned from hid_enumerate().
int HID_API_EXPORT HID_API_CALL hid_get_feature_report ( hid_device device,
unsigned char *  data,
size_t  length 
)

Get a feature report from a HID device.

Make sure to set the first byte of @p data[] to the Report
ID of the report to be read.  Make sure to allow space for
this extra byte in @p data[].
Parameters
deviceA device handle returned from hid_open().
dataA 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.
lengthThe 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 and -1 on error.
int HID_API_EXPORT_CALL hid_get_indexed_string ( hid_device device,
int  string_index,
wchar_t *  string,
size_t  maxlen 
)

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

Parameters
deviceA device handle returned from hid_open().
string_indexThe index of the string to get.
stringA wide string buffer to put the data into.
maxlenThe length of the buffer in multiples of wchar_t.
Returns
This function returns 0 on success and -1 on error.
int HID_API_EXPORT_CALL hid_get_manufacturer_string ( hid_device device,
wchar_t *  string,
size_t  maxlen 
)

Get The Manufacturer String from a HID device.

Parameters
deviceA device handle returned from hid_open().
stringA wide string buffer to put the data into.
maxlenThe length of the buffer in multiples of wchar_t.
Returns
This function returns 0 on success and -1 on error.
int HID_API_EXPORT_CALL hid_get_product_string ( hid_device device,
wchar_t *  string,
size_t  maxlen 
)

Get The Product String from a HID device.

Parameters
deviceA device handle returned from hid_open().
stringA wide string buffer to put the data into.
maxlenThe length of the buffer in multiples of wchar_t.
Returns
This function returns 0 on success and -1 on error.
int HID_API_EXPORT_CALL hid_get_serial_number_string ( hid_device device,
wchar_t *  string,
size_t  maxlen 
)

Get The Serial Number String from a HID device.

Parameters
deviceA device handle returned from hid_open().
stringA wide string buffer to put the data into.
maxlenThe length of the buffer in multiples of wchar_t.
Returns
This function returns 0 on success and -1 on error.
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.
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 @p serial_number is NULL, the first device with the
specified VID and PID is opened.
Parameters
vendor_idThe Vendor ID (VID) of the device to open.
product_idThe Product ID (PID) of the device to open.
serial_numberThe 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.
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
pathThe path name of the device to open
Returns
This function returns a pointer to a hid_device object on success or NULL on failure.
int HID_API_EXPORT HID_API_CALL hid_read ( hid_device device,
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
deviceA device handle returned from hid_open().
dataA buffer to put the read data into.
lengthThe 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.
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
deviceA device handle returned from hid_open().
dataA buffer to put the read data into.
lengthThe number of bytes to read. For devices with multiple reports, make sure to read an extra byte for the report number.
millisecondstimeout in milliseconds or -1 for blocking wait.
Returns
This function returns the actual number of bytes read and -1 on error.
int HID_API_EXPORT HID_API_CALL hid_send_feature_report ( hid_device device,
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 @p 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
deviceA device handle returned from hid_open().
dataThe data to send, including the report number as the first byte.
lengthThe 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.
int HID_API_EXPORT HID_API_CALL hid_set_nonblocking ( hid_device device,
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
deviceA device handle returned from hid_open().
nonblockenable or not the nonblocking reads
  • 1 to enable nonblocking
  • 0 to disable nonblocking.
Returns
This function returns 0 on success and -1 on error.
int HID_API_EXPORT HID_API_CALL hid_write ( hid_device device,
const unsigned char *  data,
size_t  length 
)

Write an Output report to a HID device.

The first byte of @p 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 OUT endpoint, if
one exists. If it does not, it will send the data through
the Control Endpoint (Endpoint 0).
Parameters
deviceA device handle returned from hid_open().
dataThe data to send, including the report number as the first byte.
lengthThe length in bytes of the data to send.
Returns
This function returns the actual number of bytes written and -1 on error.