XR16M890IL32-0C Datasheet, PDF (24/63 Pages) Exar Corporation – UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS

XR16M890
UART WITH 128-BYTE FIFO AND INTEGRATED LEVEL SHIFTERS
REV. 1.0.0
1.19 Infrared Mode
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 Figure 16 below.
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, SFR bit-3 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 Figure 16.
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.
FIGURE 16. INFRARED TRANSMIT DATA ENCODING AND RECEIVE DATA DECODING
Character
Data Bits
TX Data 0 ¹ 0 ¹ 0 0 ^{1 1} 0 ¹
Transmit
IR Pulse
(TX Pin)
Bit Time _{3/16 or 1/4 Bit Time}
1/2 Bit Time
IrEncoder-1
Receive
IR Pulse
(RX pin)
RX Data
Bit Time
1/16 Clock Delay
0 1 0 1 0 0 11 0 1
Data Bits
Character
IRdecoder-1
24