HId note

[github756878399]

// Toggle LED (cmd 0x80). The first byte is the report number (0x0).
buf[0] = 0x0;
buf[1] = 0x80;
res = hid_write(handle, buf, 65);

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

/** @brief 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).
@InGroup API
@PARAM device A device handle returned from hid_open().
@PARAM data The data to send, including the report number as
the first byte.
@PARAM length The length in bytes of the data to send.
@returns
This function returns the actual number of bytes written and
-1 on error.