01
011
t
t
t
t
t
Effective
t
length
Nominal
t
Modulation pulse
Carrier
uart-014
Public Version
UART/IrDA/CIR Environment
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19.2.6 CIR Functional Interfaces
19.2.6.1 CIR Interface Description
describes the CIR interface.
Table 19-10. CIR I/O Description
Signal
I/O
(1)
Description
Reset
CIR Signals
uart3_rx_irrx
I
Serial data input
Unknown
uart3_cts_rctx
O
Serial data output in CIR mode. In other modes, this pin is set to
0
the reset value (inactive state).
uart3_rts_sd
O
SD mode is used to configure the transceivers.
1
The SD pinout is an inverted value of the
UART3.
[6] SD_MOD bit.
(1)
I = Input, O = Output
19.2.6.2 CIR Protocol and Data Format
In the CIR mode, the infrared operation functions as a programmable (universal) remote control.
The CIR mode uses a variable PWM technique (based on multiples of a programmable t period) to
encompass the various formats of infrared encoding for remote control applications. The CIR logic
transmits data packets based on the user-defined frame structure and packet content.
19.2.6.2.1 Carrier Modulation
Each modulated pulse that constitutes a digit is a train of on/off pulses (see
Figure 19-13. CIR Pulse Modulation
2882
UART/IrDA/CIR
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated