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> Serial Infrared
Posted: March 19, 2018 10:04 pm
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Hello to all
is there a way to transmit data in synchronous serial mode using infrared but that is simple and safe without errors?
I would like to know if I can use this method to make an infrared remote control.
I thought of a parallel / serial scroll register for the TX and instead a serial / parallel shift register for RX.
TX and RX communicate with a dedicated LED while the clock with another infrared LED then two LEDs. a clock applied to the TX register causes it to advance one step, the next clock uses the infrared LED to activate the clock of the RX receiver.
I hope I explained myself
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Posted: March 20, 2018 11:01 am
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Well... easy way, look up the standards actually used by remote controls.

These are tone-burst, pulse coded methods, the code being based on pulse width, period, or polarity (Manchester encoding).

A complete receiver consists of: IR filter and lens, photodiode, AGC and IF amp, bandpass filter (the carrier frequency is usually 37kHz or thereabouts), and detector. This all fits inside a handy three-pin part, just add logic power (3.3-5V), and usually a pull-up resistor.

You can skimp on any of these building blocks, but you won't get as good performance. Example: omit the bandpass filter, and now it will pick up any carrier frequency, as well as ambient noise (CFLs being the most notorious offender, though nowadays, LED lights shouldn't bother anything). Omit the AGC, and it will only be sensitive over a narrow range of distances. And so on.

They are asynchronous, because the signal is precisely timed and only a single carrier is needed. Synchronous has to provide a clock somehow, and things quickly get very complicated. (Example: to avoid a parallel clock path, "self-clocking" line codings are used, like Manchester, or 8b/10b and the like, which allow a PLL to recover the clock.)


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Posted: March 20, 2018 05:46 pm
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