nano pb example

msg.proto

syntax = "proto2";

import "msg_osd.proto";

message Message {
    enum Type {
        Api = 1;
        Osd = 2;
    }
    required uint32 utime = 1;
    oneof payload {
        MsgApi msg_api = 2;
        MsgOsd msg_osd = 3;
    }
}

msg_osd.proto

syntax = "proto2";

message MsgOsd {
    enum VideoSystem {
        AUTO = 0;
        PAL = 1;
        NTSC = 2;
    }
    optional VideoSystem video_system = 1;

    enum UnitType {
        METRIC = 0;
        IMPERIAL = 1;
    }
    optional UnitType units = 2;

    message Alarm {
        optional string name = 1 [default = ""];
        optional uint32 limit = 2;
    }
    repeated Alarm alarms = 3;

    message Element {
        optional string name = 1 [default = ""];
        optional uint32 position = 2;
    }
    repeated Element elments = 4;
}