6–8
6.4
Infrared Coupling of Transmitter/Receiver— Modulated Transmission
Mode
Table 6–5 lists the parts for the schematic of an infrared receiver working in the modulated continuous
configuration shown in Figure 6–6. This modulated receiver can be used with a normal infrared transmitter
(see Figure 6–4) provided that the following guide lines are observed.
The transmitter is configured as a modulated transmitter, and the content of the configuration EEPROM cells
is:
CA
CB
CC
CD
CE
CF
CG
CH
CI
1
0
1
0
0
0
0
0
0
The oscillating frequency of the transmitter must always be 120 kHz. This is accomplished by using a correct
combination of R
osc
and C
osc
.
The receiver is cascaded with a TDA3048 (or equivalent) to process the received signal and demodulate
it. The receiver is configured as a modulated (1-code) Q-state inverting receiver, and the content of the
EEPROM cells is:
CA
CB
CC
CD
CE
CF
CG
CH
CI
0
0
0
0
0
0
0
0
1
The receiver is used in the inverting mode. The code is considered to be inverted when using OUT on the
transmitter to transmit the code. The signal path between the transmitter and receiver does not invert the
signal; using the modulated mode (CB = 0) also does not invert the signal. The result is a signal that is
inverted at the internal logic controller of the receiver; then CI = 1 for an inverting receiver. The oscillating
frequency of the receiver is approximately 900 kHz. OUT on the receiver maintains the same status for
approximately 0.5 seconds (1M
×
470 nF).
Summary of Contents for TMS3637P
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