The Host Microcontroller interprets commands and data for the User Application and performs end to end protocol functions. Output signal amplification and filtering, input signal filtering, and node coupling to the power line is accomplished using external components. SSC P300 interface to the Host system is supported through a Serial Peripheral Interface (SPI) using five I/O lines. A hardware, active-low, Reset (RST*) signal is also supplied by the Host system. A simple protocol is used to transfer commands and data between the host and SSC P300.
These commands and data include packets to be transmitted, received packets, status and configuration information. Analog data is transferred between the AC power line and the SSC P300 over the Signal In (SI) and Signal Out (SO) pins. In transmit mode, SSC chirpsfrom the SSC P300 SO pin are routed to the Output Amplifier, which is enabled by the SSC P300 Tristate (TS) signal. Once amplified, the output signal passes through a low-pass Output Filter, which removes harmonic energy (distortion) from the transmit signal, and on to the Tristate Switch.