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Potential input dial for Psychopy


I would like to use this input dial as response device in Psychopy

It is the PowerMate USB Multimedia Controller, Griffin Technology

I am just wondering whether you think it is possible at all to use, if someone has had experiences with this sort of things…and what would be required…

many thanks!


I have used them quite a bit - they’re great.

On linux, I map the dial rotations to keyboard events. That makes it straightforward to use in psychopy, as it is just like interacting with a keyboard.

Hi David,

I’ve used this dial with matlab, cambridge research systems have a ‘badged’ version which is useable in their matlab toolbox. I’d also like to know whether it’s likely to be compatible with PsychoPy as I’ve a student project that needs this kind of response.

Here’s the CRS version:

When our CB7 broke a few years ago I found the powermate version plug-in compatible.

Obviously, it doesn’t help to know that the device works with matlab/crs-toolbox. But I was wondering whether there was anything to be learned from this implementation.

Best wishes,


Hi I have tried it and seems to work nicely with Psychopy, though am still testing things

Hi David,

So I’ve borrowed a powermate, can you tell me what software you used with it? I’ve a PC and can’t seem to locate any software @garmin nor anywhere else.


Hi, I think you can download the software and also instructions from here


Hi, I think you can download the software and also instructions from here

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I’ve got it working thanks. I think it will be really useful for adjustment paradigms, particularly when there’s feedback on the screen.

Unfortunately I’m getting a lot of slip, i.e. if you mark a dot at zero degrees on the dial and move a stimulus around a lot, what was at zero degrees may now be in a different location. This occurs even after carefully tuning the exact angular step to match the switch activation in the dial. I think I might have to try an actual block of wood with some coloured chips and a webcam…

Strange it would drift that much. Is it just sending key presses on rotation or does it report some absolute value through an API? The former might result in ‘ticks’ being dropped, especially if it’s sending them out faster than PsychoPy is reading them (usually at the rate of the screen refresh) unless you’re using IoHub.

As a side note, I’ve used rotary encoders in the past with counter ICs to keep track of absolute position, which I then read-out using some microcontroller. These things can rotate practically forever (until the counter’s over/underflow) without drifting. Some microcontrollers like the ATmega32U4 (arduino leonardo) can emulate a joystick/mouse/keyboard so you can potentially make something similar which keeps track of rotation externally and feeds back the absolute position from zero as a joystick deflection.

Yes I think it’s missing ticks, it only drifts if the dial is turned quickly. I’ve made some progress with the webcam approach and intuitively makes sense because I’m asking participants to orient an object as they think it’s portrayed on the screen. Just need to translate my functioning matlab into python.