![Labelled Pro Micro Image](pro-micro-labelled-image.jpg)
The `<shield_name>.overlay` is the devicetree description of the keyboard shield that is merged with the primary board devicetree description before the build. For ZMK, this file at a minimum should include the [chosen]() node named `zmk,kscan` that references a KSCAN driver instance. For a simple 3x3 macropad matrix,