XR16C850CM EXAR [Exar Corporation], XR16C850CM Datasheet - Page 21

• Manufacturer Part Number: XR16C850CM
• Description: 2.97V TO 5.5V UART WITH 128-BYTE FIFO
• Manufacturer: EXAR [Exar Corporation]

xr
REV. 2.3.1
The 850 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 850 has a provision to invert
the input polarity to accomodate this. In this case, the user can enable FCTR bit-2 to invert the incoming
infrared RX signal.
2.20
Infrared Mode
F
IGURE
14. A
OP1#/RS485
850 UART
(0 = Transmit
1= Receive)
UTO
RS-485 H
RX
TX
ALF
Figure
Figure
-D
UPLEX
15.
15.
21
C
ONTROL
RS-485 Transceiver
2.97V TO 5.5V UART WITH 128-BYTE FIFO
D
R
T+
T-
R+
R-
XR16C850