december 22, 2016

How to control the ears of your Karotz

In this blogpost, I'll try to explain how you can control the ears of your rabbit.

To control the ears, we need a little Linux program called "ears". You can find it in /karotz/bin/. It is not included in the original firmware of Violet/Mindscape, but can be found in the compressed archive called "tools2.jar", which was included in the USB-key installation of Violet/Mindscape. 

OpenKarotz and Free Rabbits OS (FROS) both include this program in the firmware that is flashed to your Karotz. So if you're running OpenKarotz or FROS, you'll find it as /karotz/bin/ears.

Lets start:
Open a telnet session (or SSH if you prefer) and login to your Karotz with username "karotz" and a blank password. Once logged in, type the following command:


When you run /karotz/bin/ears without parameters, it will show "reset" and the ears will move to their initial position, that is pointing upwards. You can call the "ears"-program with 4 parameters:

  • 1 position left ear
  • 2 speed left ear
  • 3 position right ear
  • 4 speed right ear

The position is a number between 0 and 16, or higher. It tells an ear to go to one of the 16 different positions, starting at 0 (pointing upwards), 6 (pointing down), or 17 (pointing upwards again). When you increase a position, an ear will move forward. When finished, it will remember its new position value. When you decrease a position, it will move backwards.

An example: position 34 is the same as position 17, but from the initial position (that is zero), it will go around two times. When finished, it will remember its position (that is 34). When you then enter a higher number, the ears will move forward to this new position. When you enter a lower number, it will go backwards to the position you ask for.

Ready for some tricks? First, we will make the left ear turn around one time:

/karotz/bin/ears 17 50 0 0

This will tell your Karotz: move left ear to position 17, with a speed of 50. Now lets move the right ear to the same position:

/karotz/bin/ears 0 0 17 50

Karotz knows both ears are at position 17 now. To go forward, we need to add a higher position number. To go backward, we need to enter a lower number. Lets move both ears back to its original position:

/karotz/bin/ears 0 50 0 50

And lets make them turn around two times:

/karotz/bin/ears 34 50 34 50

And, to make a funny effect, lets move the left ear forwards, and the right ear backwards.

/karotz/bin/ears 17 50 52 50

And lets point the ears in "sleeping position", so pointing down:

/karotz/bin/ears 6 50 6 50

The right ear made multiple turns to to back to position 6. The left ear was on 17, so needed only a few steps to move to the new position.

Lets move it with different speeds now: 

/karotz/bin/ears 22 50 22 5

And reset both ears to their initial position (that is zero):


As a bonus, here are a few random positions, with a pause between each of them. We use a same technique in our Tai Chi App. You can copy and paste it and enter it as one command in your telnet or SSH session: 

/karotz/bin/ears 4 50 27 50; sleep 8; /karotz/bin/ears 28 50 13 50; sleep 8; /karotz/bin/ears 2 50 31 50; sleep 8; /karotz/bin/ears 24 50 1 50; sleep 8; /karotz/bin/ears 16 50 27 50; sleep 8; /karotz/bin/ears 26 50 5 50; sleep 8; /karotz/bin/ears 15 50 24 50; sleep 8; /karotz/bin/ears

I hope you had fun. Let me know if you have any ideas what to do with the position of the ears.

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