XR16L580 Exar Corporation, XR16L580 Datasheet - Page 17

• Manufacturer Part Number: XR16L580
• Description: Smallest 2.25 to 5.5V Uart With 16-Byte Fifo And Power-save
• Manufacturer: Exar Corporation

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REV. 1.2.0
The L580 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 L580 has a provision to invert
the input polarity to accommodate this. In this case, the user can enable MCR bit-2 to invert the IR signal at the
RX pin.
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2.17
Infrared Mode
F
IGURE
Receive
IR Pulse
(RX pin)
RX Data
T X D ata
T ransm it
(T X P in)
IR P ulse
12. I
SMALLEST 2.25V TO 5.5V UART WITH 16-BYTE FIFO AND POWERSAVE
NFRARED
0
Bit Time
B it T im e
0
1
1/16 Clock Delay
T
RANSMIT
1
0
Figure 12
Figure
0
1
C haracter
D ata B its
12.
D
1
ATA
0
17
Data Bits
3/16 B it T im e
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
XR16L580