xr16m890 Exar Corporation, xr16m890 Datasheet - Page 24

• Manufacturer Part Number: xr16m890
• Description: Uart With 128-byte Fifo And Integrated Level Shifters
• Manufacturer: Exar Corporation

XR16M890
UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS
The M890 UART includes the infrared encoder and decoder compatible to the IrDA (Infrared Data Association)
version 1.0 and 1.1. 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 with a data rate up to 115.2 Kbps. For the IrDA 1.1
standard, the infrared encoder sends out a 1/4 of a bit time wide HIGH-pulse for each "0" bit in the transmit
data stream with a data rate up to 1.152 Mbps. 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’. With this bit enabled, the
infrared encoder and decoder is compatible to the IrDA 1.0 standard. For the infrared encoder and decoder to
be compatible to the IrDA 1.1 standard, MSR bit-7 will also need to be set to a ’1’ when EFR bit-4 is set to ’1’.
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.
F
1.19
IGURE
16. I
Infrared Mode
NFRARED
T
RANSMIT
TX Data
Transmit
(TX Pin)
IR Pulse
Receive
IR Pulse
(RX pin)
RX Data
D
ATA
0
E
NCODING AND
Bit Time
Bit Time
0
1
1/16 Clock Delay
Figure 16
1
0
PRELIMINARY
0
3/16 or 1/4 Bit Time
1
Character
Data Bits
1
R
24
Data Bits
Character
0
below.
ECEIVE
0
0
0
D
1
ATA
1
1
D
1
ECODING
0
0
1
1/2 Bit Time
1
IRdecoder-1
IrEncoder-1
Figure
16.
REV. P1.1.1