ST16C654D Exar Corporation, ST16C654D Datasheet - Page 19

• Manufacturer Part Number: ST16C654D
• Description: St16c654d -quad Uart With 64-byte Fifo And Infrared Irda Encoder/decoder
• Manufacturer: Exar Corporation

xr
REV. 5.0.2
The 654 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.
2.15
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
19
3/16 Bit Time
Data Bits
below.
Character
0
E
2.97V TO 5.5V QUAD UART WITH 64-BYTE FIFO
0
NCODING AND
0
1
1 1
1
0
R
0
ECEIVE
1/2 Bit Time
1
1
IRdecoder-
IrEncoder-1
D
ATA
D
ECODING
ST16C654/654D