Interest Check: Scroll wheel expansion card

Hi everyone! How many of y’all are interested in a scroll wheel expansion card?

  • Yes, I’m interested!
  • I’m not sure…
  • a what card?
  • no.

0 voters

The idea of a scroll wheel expansion card is to have a wheel sticking slightly out of the side of the framework laptop, and can control whatever you want it to. Whether it be audio, mouse scroll, copy & paste, mouse 2D movements, this expansion card should do the job!

Here’s a mockup of what the ideal scroll wheel expansion card I have in mind:

(Oct 23) Here’s an update: I already have the schematics and PCB layout done:
(Oct 24) Changed the screenshot to reflect pcb layout change from square to framework pcb

The card will be controlled by an ATMega32U4, which means that the card will be configurable with the QMK framework.


I would love this, but having a rotary encoder or a optical sensor probably will not fit in the form factor.

1 Like

I can see something like this being useful. The Logitech MX Master 3 has a side scroll wheel that can be programmed to do a bunch of different things. I use it the most in the browser to quickly switch through tabs. In excel it scrolls left-right (I’ve always hated tilting the middle mouse wheel). I imagine if it were on the left side and easy to reach it might actually be pretty handy.


Sorted interested, yes.

Here’s the github page to my board design. The first iteration of this card has a non-expansion card PCB size, so it will not fit the reference design cases.

Since this card will include a rotary encoder, it will be impossible to fit into a regular sized expansion card. As much as I would like to, having only 1.5mm of clearance between the PCB and the cap height of the plastic on the expansion card is impossible for this project.

Reference measurements for the PCB and cap height for card

(Depth of space between the PCB and the top) - (thickness of the plastic) = 2.8mm - 1.3mm = 1.5mm of space to work with.

I hope people don’t mind that this expansion card being taller than the standard.

There are other “double height” designs floating around. We could really, really use a standard for those, so various “double height” cards can be compatible (i.e. not make the laptop lopsided).


@Framework or @nrp, care to comment? (Please?!)


Instead of a scroll wheel with an encoder – what about a capacitive touch strip that you can slide your finger across? Think like the way the touchpad works — slide your finger up and down and across rather than turning a wheel with an encoder.

Using a 32U4 processor is still completely doable and within the form factor and building a multi-segment capacitive touch slider can be done on a flexPCB.


I think this is a cool idea, and I’m really into it. I do have two thoughts to share.

  1. QMK is lovely, but many applications don’t support rotary encoders without an interface application of some kind. You may want to try finding, building, or working with someone to build a companion application to interface with some popular programs (Adobe’s rubbish and some CAD programs).

  2. A double height card is probably not the most marketable, or practical design. I think you’d be able to circumvent the large Z axis height though by dropping the rotary encoder, and replacing with a hall effects based encoder. You could probably achieve this by either having the dial its self be a two piece design with embedded magnets, or a single milled/3d printed component that has an inner channel for the magnets that is not exposed visible to the outside. Then pair either dial with some mounting mechanism, and a PCB with the hall effects sensor onboard. All should still be able to run off of that same ATMega. Let me know if I didn’t explain the thought too well, and if so I can shoot over a 3D.

Best of luck in your design and production efforts.


I like the idea of the hall effects encoder and the touch input, but my goal in this expansion card is to be:

  • cheap/affordable – already failed
  • same form factor as regular expansion card – also failed
  • OS independent – achievable with the QMK framework once set up

I can see the touch input happening, and maybe squeezing it within the 1mm space on a small form card, but I don’t have the hardware experience, nor the budget to implement it. As for the hall effects encoder, I see some alternatives out there, but they are more expensive and taller… unless, of course, my search/google/ddg skills are failing me.