The Serial Peripheral Interface (SPI) is an excellent method of providing inter- processor communications for multi-processor embedded systems. However, concurrent development of the master and slave applications can result in increased test and debugging time, due to both ends of the communication link being unproven software. The SPI-UART Gateway application allows the developer to test and debug an SPI slave application isolated from the master, using manually controlled communications via a suitable RS232 terminal; for example a serial port terminal emulator running on a PC.