void foo(int a,int b,unsigned char c)
{

    static volatile unsigned char tmp = 0;

    struct net_buf_simple *msg1 = NET_BUF_SIMPLE(2+4+2);

    struct bt_mesh_msg_ctx ctx1 = {
        .net_idx = b,
        .app_idx = a,
        .addr = 0xC001,
        .send_ttl = BT_MESH_TTL_DEFAULT,
    };

   
    bt_mesh_model_msg_init(msg1, BT_MESH_MODEL_OP_2(0x82, 0x03));

    net_buf_simple_add_u8(msg1,c);            // <------------------------------------------------------- C is 0 or 1
    net_buf_simple_add_u8(msg1, 00);    //<-------------------------------------------------------- what to send from here ??

                                                                                                                       // If I didn't add this then firmware throws error after receiving message.

    if (bt_mesh_model_send(&root_models[2], &ctx1, msg1, NULL, NULL)) {
        printk("Unable to send Vendor Button message\n\r");
    }

    printk("Button message sent with OpCode 0x%08x......\n\r", BT_MESH_MODEL_OP_2(0x82, 0x03));

}