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f808275822
We first check that the HID device is managed by the kernel before calling libusb_detach_kernel_driver(). This will avoid side effects of libusb_detach_kernel_driver() like also doing a libusb_release_interface() Ludovic's original patch modified by Alan Ott <alan@signal11.us> |
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.gitignore | ||
hid-libusb.c | ||
hid.c | ||
Makefile | ||
README.txt |
There are two implementations of HIDAPI for Linux. One (hid.c) uses the Linux hidraw driver, and the other (hid-libusb.c) uses libusb. Which one you use depends on your application. Complete functionality of the hidraw version depends on patches to the Linux kernel which are not currently in the mainline. These patches have to do with sending and receiving feature reports. The libusb implementation uses libusb to talk directly to the device, bypassing any Linux HID driver. The disadvantage of the libusb version is that it will only work with USB devices, while the hidraw implementation will work with Bluetooth devices as well. To use HIDAPI, simply drop either hid.c or hid-libusb.c into your application and build using the build parameters in the Makefile. By default, on Linux, the Makefile in this directory is configured to use the libusb implementation. To switch to the hidraw implementation, simply change hid-libusb.c to hid.c in the Makefile. Libusb Implementation notes ---------------------------- For the libusb implementation, libusb-1.0 must be installed. Libusb 1.0 is different than the legacy libusb 0.1 which is installed on many systems. To install libusb-1.0 on Ubuntu and other Debian-based systems, run: sudo apt-get install libusb-1.0-0-dev Hidraw Implementation notes ---------------------------- For the hidraw implementation, libudev headers and libraries are required to build hidapi programs. To install libudev libraries on Ubuntu, and other Debian-based systems, run: sudo apt-get install libudev-dev On Redhat-based systems, run the following as root: yum install libudev-devel Unfortunately, the hidraw driver, which the linux version of hidapi is based on, contains bugs in kernel versions < 2.6.36, which the client application should be aware of. Bugs (hidraw implementation only): ----------------------------------- On Kernel versions < 2.6.34, if your device uses numbered reports, an extra byte will be returned at the beginning of all reports returned from read() for hidraw devices. This is worked around in the libary. No action should be necessary in the client library. On Kernel versions < 2.6.35, reports will only be sent using a Set_Report transfer on the CONTROL endpoint. No data will ever be sent on an Interrupt Out endpoint if one exists. This is fixed in 2.6.35. In 2.6.35, OUTPUT reports will be sent to the device on the first INTERRUPT OUT endpoint if it exists; If it does not exist, OUTPUT reports will be sent on the CONTROL endpoint. On Kernel versions < 2.6.36, add an extra byte containing the report number to sent reports if numbered reports are used, and the device does not contain an INTERRPUT OUT endpoint for OUTPUT transfers. For example, if your device uses numbered reports and wants to send {0x2 0xff 0xff 0xff} to the device (0x2 is the report number), you must send {0x2 0x2 0xff 0xff 0xff}. If your device has the optional Interrupt OUT endpoint, this does not apply (but really on 2.6.35 only, because 2.6.34 won't use the interrupt out endpoint).