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các loại remote TV,... ngoại trừ đầu đĩa.dều dùng kỹ thuật mã hóa Manchester ,bạn có thể dể dàng dọc dược mã bằng cách dùng vi dk ,PIC chẳng hạn.

đọc kỹ cái này nhé,nó hướng dẫn khá chi tiết

RC5 TRANSMISSION PROTOCOL
To ensure immunity to interference from other IR
sources such as the sun, lamps and IR sound trans-missions
(to headphones), bi-phase encoding (also
called Manchester encoding) is used for RC5 code
words. As shown in figure 2 each bi-phase encoded
bit is a symbol comprising two logic levels with a tran-sition
in the middle.
As shown in figure 3, the bi-phase code words modu-late
a 36 kHz carrier, before being transmitted via the
IR LED. Since the repetition period of the 36 kHz car-rier
is 27.778 us and the duty factor is 25 %, the car-rier
pulse duration is 6.944 us.
Because the high part of each bit of the RC5 code
word contains 32 carrier pulses, 1 bit period is 64 x
27.778 us = 1.778 ms.
A complete RC5 code word contains 14 bits, so it
takes 24.889 ms to transmit. Each 14 bit RC5 code
word consists of:
§ a field bit (F) which denotes command codes 0 to
63 or 64 to 127
§ a control bit (C) which toggles after each key re-lease
and initiates a new transmission
§ five system address bits for selecting one of 32
possible systems
§ six command bits representing one of the 128
possible RC5 commands
SOFTWARE
Main loop (see figure 4)
After initialisation of the hardware, the four scan-lines
(port pins P1.0-3) are pulled low and the LPC76x is
forced into power down mode.
If one of the 16 keys is pressed a keyboard interrupt
will be generated and the micro will wake up from
power down mode. The main program checks for a
valid key hit. Next, the control bit (C) of the system
byte is set or reset. After that, a routine is called for
sending out the key info as an RC5 code word. Fi-nally
power down mode is entered again, waiting to
wake up at the next keyboard or watchdog interrupt.