PC87108 Advanced UART and Infrared Controller
ADVANCE INFORMATION
November 1995
PC87108
Advanced UART and Infrared Controller
General Description
The PC87108 is a serial communications device with infra-
red capability It supports 6 modes or operation and is back-
ward 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
an internal 16-bit address decoder or an externally generat-
ed 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 compatibil-
ity mode when the standard baud generator divisor registers
are accessed
The device architecture has been optimized to meet the
requirements of a variety of UART and infrared based appli-
cations DMA support for all operational modes has been
incorporated into the architecture Routing for interrupt and
DMA handshake signals is provided to meet Plug-and-Play
as well as PC鈥?5 requirements
The device can use either 1 or 2 DMA channels One chan-
nel 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 design and simplify the implementa-
tion of infrared protocols a 12-bit timer with 1 ms resolution
has also been included
Features
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Fully compatible with 16550 and 16450 devices
Enhanced UART mode
Sharp-IR with selectable internal or external
modulation
IrDA 1 0 SIR with up to 115 2 kbps data rate
IrDA 1 1 MIR and FIR with 1 152 and 4 0 Mbps data
rates
Consumer remote control mode
UART mode baud rates up to 1 5 Mbps
Back-to-back infrared frame transmission and reception
Full duplex infrared capability for diagnostics
Transmit deferral
Automatic fallback to 16550 compatibility mode
IrDA modes pipelining
Selectable 16 or 32 level FIFOs
Multiple optical transceiver support
Automatic or manual transceiver configuration
12-bit timer for infrared protocol support
4 general purpose I O pins
Interrupt signal routing to 1 of 7 output pins
DMA handshake signal routing for either 1 or 2
channels
Full 16-bit address decode
Selectable base address or chip select mode
Power management support
3 3V and 5V operation
ISA compatible interface
80-pin PQFP or TQFP package
Block Diagram
TL XX 0249 鈥?1
C
1996 National Semiconductor Corporation
TL XX 0249
RRD-B30M66 Printed in U S A
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