Circuit, apparatus, method, and signal set for sending and controlling bi-directional data flow between a microprocessor (or other device) and a peripheral device having a standard UART-based, SPI-based, or similar interface over a single input/output (I/O) port line, utilizing the differences of the instantaneous source impedance of the I/O port line operating with data in and data out states. Circuit, apparatus, method, and signal set for separating the 1-wire data into standard 2-wire and 3-wire UART-based, SPI-based, or similar interfaces for use with unmodified peripheral devices. The exchange of data on a bit-by-bit or analog basis, with insignificant return delay, allows operation independent of any signaling protocol.