Communication circuit for bidirectional communication. A switching part is provided including a first BJT having a first base, a first collector, and a first emitter connected to an IO line. The first BJT is activated in response to an input data signal. A transmitter part is provided including a second BJT having a second base connected to the first collector, and a second collector connected to an output. A receiver part is provided comprising a third BJT having a third base connected to an input, and a third collector connected to the first base and to the IO line. A diode is provided in the IO line for impeding current associated with an input data signal and conducting a current associated with an output data signal.