A method, systems, and devices are disclosed. An example method includes determining whether an external unit of an implanted medical device is coupled to an implanted unit of the implanted medical device. In response to determining that the external unit is coupled to the implanted unit, the example method includes causing the external unit to operate in a first operating mode. In response to determining that the external unit is not coupled to the implanted unit, the example method includes causing the external unit to operate in a second operating mode.