qmk_firmware/keyboards/handwired/pill60/blackpill_f401/keyboard.json

{
    "usb": {
        "shared_endpoint": {
            "keyboard": true
        }
    },
    "matrix_pins": {
        "cols": ["A8", "B2", "B1", "B15", "A10", "A0", "A1", "A2", "A3", "A4", "A5", "A6", "A7", "B0"],
        "rows": ["B4", "B3", "A15", "B13", "B5"]
    },
    "diode_direction": "COL2ROW",
    "processor": "STM32F401",
    "bootloader": "stm32-dfu",
    "board": "BLACKPILL_STM32_F401"
}