platformio-core/platformio/boards/misc.json

{
    "raspduino": {
        "build": {
            "core": "arduino",
            "extra_flags": "-DARDUINO_ARCH_AVR -DAVR_RASPDUINO",
            "f_cpu": "16000000L",
            "mcu": "atmega328p",
            "variant": "standard"
        },
        "framework": "arduino",
        "name": "Raspduino",
        "platform": "atmelavr",
        "upload": {
            "maximum_ram_size": 2048,
            "maximum_size": 30720,
            "protocol": "arduino",
            "speed": 57600
        }
    }
}