xr16l2750im Exar Corporation, xr16l2750im Datasheet - Page 17

• Manufacturer Part Number: xr16l2750im
• Description: High-performance 2.25v - 5.5v Duart
• Manufacturer: Exar Corporation

xr
REV. 1.2.1
transmitter automatically re-asserts RTS# (LOW) output prior to sending the data. The RS485 half-duplex
direction control output can be inverted by enabling EMSR bit-3.
The 2750 UART includes the infrared encoder and decoder compatible to the IrDA (Infrared Data Association)
version 1.0. The IrDA 1.0 standard that stipulates the infrared encoder sends out a 3/16 of a bit wide HIGH-
pulse for each “0” bit in the transmit data stream. This signal encoding reduces the on-time of the infrared LED,
hence reduces the power consumption. See
The infrared encoder and decoder are enabled by setting MCR register bit-6 to a ‘1’. When the infrared feature
is enabled, the transmit data output, TX, idles at logic zero level. Likewise, the RX input assumes an idle level
of logic zero from a reset and power up, see
Typically, the wireless infrared decoder receives the input pulse from the infrared sensing diode on the RX pin.
Each time it senses a light pulse, it returns a logic 1 to the data bit stream. However, this is not true with some
infrared modules on the market which indicate a logic 0 by a light pulse. So the 2750 has a provision to invert
the input polarity to accommodate this. In this case user can enable FCTR bit-2 to invert the input signal.
2.19
Infrared Mode
F
IGURE
Receive
IR Pulse
(RX pin)
RX Data
TX Data
Transmit
(TX Pin)
IR Pulse
12. I
NFRARED
0
Bit Time
Bit Time
0
1
1/16 Clock Delay
T
RANSMIT
1
0
Figure 12
Figure
0
1
Character
Data Bits
12.
D
1
ATA
0
17
3/16 Bit Time
Data Bits
below.
Character
0
E
0
NCODING AND
0
1
2.25V TO 5.5V DUART WITH 64-BYTE FIFO
1 1
1
0
R
0
ECEIVE
1/2 Bit Time
1
1
IRdecoder-
IrEncoder-1
D
ATA
D
ECODING
XR16L2750