qmk_firmware/keyboards/bastardkb/charybdis/3x5/blackpill/info.json

{
    "keyboard_name": "Charybdis Nano (3x5) Blackpill",
    "usb": {
        "device_version": "1.0.0"
    },
    "matrix_pins": {
        "cols": ["B1", "B10", "B3", "B4", "B5"],
        "rows": ["A2", "B8", "A8", "B9"]
    },
    "diode_direction": "ROW2COL",
    "processor": "STM32F411",
    "bootloader": "stm32-dfu",
    "board": "BLACKPILL_STM32_F411"
}