Example implementations relate to serial port pin voltages. For example, an apparatus includes a first input device to receive a first input based on a setting, a second input device to receive a second input based on the setting, and a third input device to receive a third input based on the setting. The apparatus also includes a circuit coupled to the first input device, the second input device, and the third input device. In response to the first input, the second input, and the third input, the circuit is to provide a first voltage to a first pin of a serial port and a second voltage to a second pin of the serial port. The first voltage and the second voltage are defined by the setting.