4.7.2. KMI functional overview

This section provides a functional overview of the Keyboard and Mouse Interface (KMI). For detailed information about the KMI, see KMI (PL050) Technical Reference Manual.

The APB interface and register block provides the interface with the APB and control registers. All control register bits are synchronized to the main clock for KMI logic before they are used in the KMI core. This block also generates individual transmit and receive interrupts.

The transmit block converts the parallel transmit data into a serial bit stream with a rate dependent on the incoming KMI clock signal. This block performs odd parity generation, data framing, and parallel-to-serial conversion. This block operates on KMIREFCLK (that on the baseboard is supplied by CLK24MHz) with the incoming clock signal KMICLKIN providing the bit-rate information. The data is shifted out on the falling edge of the KMICLKIN input.

The receive block performs serial-to-parallel conversion on the serial data stream received on the KMIDATAIN input pin. The falling edge on the synchronized and sampled KMICLKIN input signal is used to sample the KMIDATAIN input line. The KMIDATAIN input is synchronized to the KMIREFCLK clock.

The controller controls transmit and receive operations. If simultaneous requests for transmission and reception occur, the transmit request is given priority.

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