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How do I change the keymap of a single device (Logitech presenter)?

rated 0 times [ 15] [ 0] / answers: 1 / hits: 25316 / 2 Years ago, sat, june 4, 2022, 6:38:51

My Logitech R400 presenter sends the following key codes:

keycode 112 (keysym 0xff55,  Prior) [page up]

keycode 117 (keysym 0xff56,   Next) [page down]

keycode  60 (keysym   0x2e, period)

keycode  71 (keysym 0xffc2,     F5)

keycode   9 (keysym 0xff1b, Escape)

Basically, I want to use this presenter to remotely control Banshee, so I'd like to remap Prior to B, Next to N, and so on.

How can I change the keymap for this device only (as I certainly don't want to remap those key codes globally)?

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brasiplacar

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answered 2 Years ago utilitere · Accepted Answer

I never did that but I think you need to create a keymap file in /lib/udev/keymaps/ and add a rule for your device to /lib/udev/rules.d/95-keymap.rules

Details:

An udev keymap maps scan codes to key codes, so you need to find both to create the keymap file. To find the scan codes run the following and press the buttons on the device:
```
sudo /lib/udev/keymap -i input/event5
```
You might need to try different numbers for event*. The output should look like this:
```
scan code: 0x70037   key code: dot

scan code: 0x70029   key code: esc

scan code: 0x7003E   key code: f5

scan code: 0x7004B   key code: pageup

scan code: 0x7004E   key code: pagedown
```
A list of key codes can be found here.

Now create the keymap file (I'm storing it as /lib/udev/keymaps/logitech-r400):
```
0x70037 brightnessdown

0x70029 brightnessup

0x7003E brightnessdown

0x7004B brightnessup

0x7004E brightnessdown
```
Doesn't do anything useful - just a test to easily see if it works.

To test the new keymap temporarily, run:

sudo /lib/udev/keymap input/event5 /lib/udev/keymaps/logitech-r400

which should result in output like this:

Remapped scancode 0x70037 to 0xe0 (prior: 0x34)

Remapped scancode 0x70029 to 0xe1 (prior: 0x01)

Remapped scancode 0x7003e to 0xe0 (prior: 0x3f)

Remapped scancode 0x7004b to 0xe1 (prior: 0x68)

Remapped scancode 0x7004e to 0xe0 (prior: 0x6d)

The buttons should now change the brightness.

If you want to make that change permanent, you need to add an udev rule to /lib/udev/rules.d/95-keymap.rules that applies the keymap file to the device.
1. Open the file: gksudo gedit /lib/udev/rules.d/95-keymap.rules
2. At the bottom of the file, but before the LABEL="keyboard_end" line, add:
```
ENV{ID_VENDOR}=="Logitech*", ATTRS{idProduct}=="c52d", RUN+="keymap $name logitech-r400"
```
3. Save, close, and after a reboot the buttons should change the brightness.