XR16C850 Datasheet, PDF (12/55 Pages) Exar Corporation – UART with 128-byte FIFO’s FIFO Counters and Half-duplex Control

XR16C850
SYMBOL DESCRIPTION
Symbol
TX / IRTX
CLKSEL
-DMA
Pin
Signal
40 44 48 52 type
Pin Description
or “mark” condition). The inactive state (no data) for
the Infrared decoder interface is a logic 0. MCR bit-
6 selects the standard modem or infrared interface.
During the local loopback mode, the RX pin is
disconnected and TX data is internally connected to
the RX input, see figure 12.
11 13
8
8
O Transmit Data - This pin provides the serial transmit
data from the 850. Two user selectable interface
options are available. The first user option supports
a standard modem interface. The second option
provides an Infrared encoder interface, see figures 2
and 3. When using the standard serial interface, the
TX signal will be a logic 1 during reset, idle (no data),
or when the transmitter is disabled. The inactive
state (no data) for the Infrared encoder interface is a
logic 0. MCR bit-6 selects the standard serial or
infrared interface. During the local loopback mode,
the TX pin is disconnected and TX data is internally
connected to the RX input, see figure 12.
-
-
13 14
I
Clock Select Bit (internal pull-up). - The 1X or 4X pre-
scaleable clock is selected by this pin. The 1X clock
is selected when CLKSEL is a logic 1 (connected to
VCC) or the 4X is selected when CLKSEL is a logic
0 (connected to GND). MCR bit-7 can override the
state of this pin following reset or initialization (see
MCR bit-7). This pin is not available on 40 and 44 pin
packages which provide MCR bit-7 selection only.
-
-
-
20
I
DMA mode enable (internal pull-up). DMA mode is
enabled when this pin is connected to GND. TC, -
DACK, DRQ functions are activated when DMA
mode is selected. TX and RX DMA mode can then
be selected by register EMSR bit 2. Connect this
pin to VCC when DMA mode is not used.
Rev. 1.20
12