USB human interface devices with Linux

I want to use a plastic drum pad to trigger sounds on the computer. It is connected by USB. It is not supported by Mac OS X by default. It is not a MIDI device.

Device connection

The following appears in /var/log/messages

Dec  4 21:11:13 colourbox kernel: usb 1-2: new low speed USB device using uhci_hcd and address 3
Dec  4 21:11:13 colourbox kernel: usb 1-2: configuration #1 chosen from 1 choice
Dec  4 21:11:13 colourbox kernel: usbcore: registered new driver hiddev
Dec  4 21:11:13 colourbox kernel: hiddev96: USB HID v1.00 Device [HID 1941:8021] on usb-0000:00:14.2-2
Dec  4 21:11:13 colourbox kernel: usbcore: registered new driver usbhid
Dec  4 21:11:13 colourbox kernel: drivers/usb/input/hid-core.c: v2.6:USB HID core driver

The following device node appears

# ls -al /dev/usb/hiddev0 
crw-rw---- 1 root root 180, 96 2008-12-04 21:53 /dev/usb/hiddev0

# lsusb
Bus 001 Device 004: ID 1941:8021  
Bus 001 Device 001: ID 0000:0000 

# lsusb -D /proc/bus/usb/001/004 
Device: ID 1941:8021  
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0         8
  idVendor           0x1941 
  idProduct          0x8021 
  bcdDevice            1.00
  iManufacturer           0 
  iProduct                0 
  iSerial                 0 
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           34
    bNumInterfaces          1
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xa0
      (Bus Powered)
      Remote Wakeup
    MaxPower              100mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           1
      bInterfaceClass         3 Human Interface Devices
      bInterfaceSubClass      0 No Subclass
      bInterfaceProtocol      0 None
      iInterface              0 
        HID Device Descriptor:
          bLength                 9
          bDescriptorType        33
          bcdHID               1.00
          bCountryCode            0 Not supported
          bNumDescriptors         1
          bDescriptorType        34 Report
          wDescriptorLength      52
         Report Descriptors: 
           ** UNAVAILABLE **
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x81  EP 1 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0008  1x 8 bytes
        bInterval              10
Device Status:     0x0000
  (Bus Powered)

Using the code Chuck hid example code from here.

# chuck hdi.ck /dev/usb/hiddev0
[hiddev0]:line(1).char(1): illegal token
[hiddev0]:line(1).char(2): illegal token
[hiddev0]:line(1).char(3): illegal token
....

See also

• Chuck hid example code
• forum post