XR16L2751CM EXAR [Exar Corporation], XR16L2751CM Datasheet - Page 19

• Manufacturer Part Number: XR16L2751CM
• Description: 2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
• Manufacturer: EXAR [Exar Corporation]

XR16L2751
2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
REV. 1.0.0
The 2751 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 2751 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
T X D ata
T ransm it
IR P ulse
(T X P in)
12. I
NFRARED
0
Bit Time
B it T im e
0
1
1/16 Clock Delay
T
RANSMIT
1
0
Figure
Figure 12
0
1
C haracter
D ata B its
12.
D
1
ATA
0
19
3/16 B it T im e
Data Bits
below.
Character
0
E
0
NCODING AND
0
1
1
1
1
0
R
0
ECEIVE
1/2 B it T im e
1
1
IRdecoder-1
IrE ncoder-1
D
ATA
D
ECODING
áç
áç
áç
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