mbed-os/platform/mbed_lib.json

{
    "name": "platform",
    "config": {
        "stdio-convert-newlines": {
            "help": "Enable conversion to standard newlines on stdin/stdout",
            "value": false
        },

        "stdio-baud-rate": {
            "help": "Baud rate for stdio",
            "value": 9600
        },

        "stdio-flush-at-exit": {
            "help": "Enable or disable the flush of standard I/O's at exit.",
            "value": true
        },

        "default-serial-baud-rate": {
            "help": "Default baud rate for a Serial or RawSerial instance (if not specified in the constructor)",
            "value": 9600
        }
    },
    "target_overrides": {
        "EFM32": {
            "stdio-baud-rate": 115200
        }
    }
}