Custom USB HID Keyboard

  • 13 April 2024
  • 1 reply


I’m trying to create a streamdeck-style custom keyboard with an Arduino as a USB HID device, which issues specific key combinations such as CTRL + 0 to zoom to 100%.

Everything is working so far apart from zoom in using CTRL + +. It seems to be intercepted by the browser and performs a browser zoom, despite other variations working as expected:

  • CTRL + -: zooms out Miro board (as expected)
  • -: zooms out Miro board in/out (as expected)
  • CTRL + 0: zooms Miro board to 100% (as expected)
  • CTRL + RIGHT/LEFT/UP/DOWN: scrolls canvas (as expected)
  • MOUSE SCROLL UP/DOWN: zooms in/out at the cursor location (as expected)
  • CTRL + +: zooms the browser window
  • +: does nothing

Does anyone know of a specific key combinations I could use to ensure the browser doesn’t intercept? (I’m working in Microsoft Edge on Windows; I haven’t tried other browsers).



1 reply

I found the issue… I was sending the plus character which is effectively SHIFT + =. The keypad plus key uses a different key code.

All working now :-)