A linux driver for the Scythe usb footswitch II

This is my driver to manage the Scythe usb footswitch II.

Motivations

I use a modal editor for programming, I keep switching modes all the time. One day I just found convenient to use my feet to switch between modes while programming. I bought a Scythe usb footswitch II to use under GNU/Linux. As expected it came with a Windows driver only. When plugin it on a PC running a Linux kernel, pressing the pedals only sends numbers.

In a first time I've been using an evdev driver patch and an Xorg configuration explained by this tutorial

It worked fine, but it was really annoying to set up, and I didn't like the idea of patching the evdev driver. So I decided to make my own driver to manage the device.

Compilation

Pre-requisite

Be sure to have your running kernel sources installed. See customization before compiling.

Build

Just run make.

Install

You have to load the driver, just run the load_driver.sh script as root. Then plug your device. By default the device is binded to the usbhid driver. The script will do what's necessary for it to be binded to the driver when you plug it.

Customization

You'll have to customize the driver for your device. Configuration information are in the footswitch_config.h file.

Device identifiers

Check that the device ids are matching your devices one.

To do so just plug your device run:

lsusb

You should see a line like this one:

Bus 00x Device 00x: ID 0426:3011 Integrated Device Technology, Inc.

Check that the ID's are matching. The vendor id will be ok, but the device id may change. Here, 0426 is the vendor id and 3011 is the device id. In the code, check the values from lsusb are maching, and change the following code if necessary:

#!c

#define VENDOR_ID 0x0426
// Change it depending on your device
#define PRODUCT_ID 0x3011

Pedals actions

So far there are no way to configure the driver with a userland file, values are written in the code. To change the values, just search for the following code

#!c

#define FS_PEDALS 3

/*!
 * structure holding keycodes for the footswtich driver
 * replace keycode with the proper values
 * Those values are listed in linux/include/linux/input.h or
 * linux/include/uapi/linux/input.h for latest kernels
 */
static const unsigned char                          usb_fs_keycode[FS_PEDALS] =
{
    63, 65, 64
};

And change the 3 values by the one you want to affect the pedals to. Those values are mapped from left to right (means the first one will be the assigned to the left pedal and the last one to the right pedal). Do not forget to change the FS_PEDALS to the the number of pedals of your switch!

The list of values are listed in the file indicated in the comments. Here is a set of useful values taken from this file. Of course you can use other values as long as it is a valid keycode for your running kernel.

#!c

#define KEY_ESC         1
#define KEY_1           2
#define KEY_2           3
#define KEY_3           4
#define KEY_4           5
#define KEY_5           6
#define KEY_6           7
#define KEY_7           8
#define KEY_8           9
#define KEY_9           10
#define KEY_0           11
#define KEY_MINUS       12
#define KEY_EQUAL       13
#define KEY_BACKSPACE   14
#define KEY_TAB         15
#define KEY_Q           16
#define KEY_W           17
#define KEY_E           18
#define KEY_R           19
#define KEY_T           20
#define KEY_Y           21
#define KEY_U           22
#define KEY_I           23
#define KEY_O           24
#define KEY_P           25
#define KEY_LEFTBRACE   26
#define KEY_RIGHTBRACE  27
#define KEY_ENTER       28
#define KEY_LEFTCTRL    29
#define KEY_A           30
#define KEY_S           31
#define KEY_D           32
#define KEY_F           33
#define KEY_G           34
#define KEY_H           35
#define KEY_J           36
#define KEY_K           37
#define KEY_L           38
#define KEY_SEMICOLON   39
#define KEY_APOSTROPHE  40
#define KEY_GRAVE       41
#define KEY_LEFTSHIFT   42
#define KEY_BACKSLASH   43
#define KEY_Z           44
#define KEY_X           45
#define KEY_C           46
#define KEY_V           47
#define KEY_B           48
#define KEY_N           49
#define KEY_M           50
#define KEY_COMMA       51
#define KEY_DOT         52
#define KEY_SLASH       53
#define KEY_RIGHTSHIFT  54
#define KEY_KPASTERISK  55
#define KEY_LEFTALT     56
#define KEY_SPACE       57
#define KEY_CAPSLOCK    58
#define KEY_F1          59
#define KEY_F2          60
#define KEY_F3          61
#define KEY_F4          62
#define KEY_F5          63
#define KEY_F6          64
#define KEY_F7          65
#define KEY_F8          66
#define KEY_F9          67
#define KEY_F10         68

Status

So far the driver has been working with linux kernels 3.9.x and 3.10.x It has only been tested with a 3 pedals footswitch, so if you're experiencing problems with an other model, please raise an issue.

Other information:

See the device

Special thanks

A huge thank to Dorian Zaccaria who helped me a lot in the documentation process to make this driver.

Wiki

usb_footswitch_driver / Home