XR17V352IB-0A-EVB Datasheet, PDF (36/64 Pages) Exar Corporation – HIGH PERFORMANCE DUAL PCI EXPRESS UART

XR17V352
HIGH PERFORMANCE DUAL PCI EXPRESS UART
REV. 1.0.4
bit wide pulse. For exact 3/16 or 1/4 of a bit wide pulse, the 16X sampling rate should be used and DLD[3:0] =
’0000’. The IR pulse width can vary if DLD[3:0] is not ’0000’.
The infrared decoder receives the input pulse from the infrared sensing diode on RX pin. Each time the
decoder senses a light pulse, it returns a "0" to the data bit stream. The RX input signal may be inverted prior
delivered to the input of the decoder via internal register setting. This option supports active LOW instead of
normal active HIGH pulse from some infrared modules on the market.
FIGURE 12. 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)
Bit Time
1/16 Clock Delay
RX Data
0 1 0 1 0 0 11 0 1
Data Bits
Character
IRdecoder-
3.4 Internal Loopback
Each UART channel provides an internal loopback capability for system diagnostic. The internal loopback
mode is enabled by setting MCR register bit [4] to a logic 1. All regular UART functions operate normally.
Figure 13 shows how the modem port signals are re-configured. Transmit data from the transmit shift register
output is internally routed to the receive shift register input allowing the system to receive the same data that it
was sending. The TX pin is held at HIGH or mark condition while RTS# and DTR# are de-asserted. The CTS#,
DSR#, CD# and RI# inputs are ignored.
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