PC87108

The PC87108 is a serial communications device with infrared capability. PC87108 supports 6 modes or operation and is backward compatible with the 16550 and 16450. The operational modes are: UART, Sharp-IR, IrDA 1.0 SIR, IrDA 1.1 MIR and FIR, and Consumer Remote Control (commonly referred to as TV Remote).

Two methods are provided to access the internal registers PC87108: an internal 16-bit address decoder, or an externally generated chip select in combination with an internal 4-bit address decoder are used to generate the internal register select. When the internal 16-bit address decoder is used, any one of four PC COMM port legacy addresses can be selected as the base address. In order to support existing legacy software using the 16550 UART, the PC87108 provides a special fallback mechanism that automatically switches the device to 16550 compatibility mode when the standard baud generator divisor registers are accessed.

PC87108 architecture has been optimized to meet the requirements of a variety of UART and infrared based applications. DMA support for all operational modes has been incorporated into the architecture. Routing for interrupt and DMA handshake signals of PC87108is provided to meet Plug-and-Play as well as PC'95 requirements.

PC87108 can use either 1 or 2 DMA channels. One channel is required for infrared based applications since infrared communications work in half duplex fashion. Two channels would normally be needed to handle high-speed full duplex
UART based applications. To further ease driver of PC87108 design and simplify the implementation of infrared protocols, a 12-bit timer with 1 ms resolution has also been included.