DLH + DLL
/ 16
CFPS
/ 12
DEMOD
16T
12CF
VOTE3
SHIFT
16T 12CF
CIR Transmitter
CIR Receiver
Carrier Frequency
Prescaler
DATA TO RX FIFO
CF: Carrier Freq
RX
RCTX
48 MHz
clk
/ 1 to (2^14 -1)
DATA FROM TX
FIFO
SHIFT REG (no
delays between
bytes on TX)
Pulse Duty 1/3 or 1/4
or 5/12 or 1/2
/ 1 to (2^8 - 1)
Auto Start
Detect
Manual or
Automatic stop
start- bit
"0"
"1"
T
2.4 ms
1.8 ms
1.2 ms
Frame space
(variable)
Complete frame
(45 ms)
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Functional Description
Figure 19-29. SIRC Bit Transmission Example
It is beyond the scope of this document to describe all encoding methods and techniques, the previous
information was provided to illustrate the consideration required to employ different encoding methods for
different industry standard protocols. The user should refer to industry standard documentation for specific
methods of encoding and protocol usage.
19.3.8.3.2 CIR Mode Operation
Depending on the encoding method (variable pulse distance / bi-phase), the LH should develop a data
structure that combines the 1 and 0 with a T period in order to encode the complete frame to transmit.
This can then be transmitted to the infrared output with a method of modulation shown in the following
diagram.
Figure 19-30. CIR Mode Block Components
3491
SPRUH73H–October 2011–Revised April 2013 Universal Asynchronous Receiver/Transmitter (UART)
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