Re: Ir remotes

On 5/20/24 1:07 PM, LM wrote:

On Mon, 20 May 2024 00:01:18 -0700, Don Y
<blockedofcourse@foo.invalid> wrote:
 

My understanding is that Ir remotes modulate an Ir "carrier" signal
in a particular pattern to express a particular "code" corresponding to
the key pressed/held.
>
And, that different "chipsets" use different carriers and encodings.
>
Is there a front-end that is tuned to the particular carrier
in the receiver?  Or, is all of this done "digitally"?
>
I.e., with a fast-enough (Ir) photodetector, should I be able to
decode ANY signal from ANY "remote"?
>
Said another way, is the fact that a particular device ONLY
recognizes a particular remote related to its use of a particular
chipset (or, equivalently, decoding algorithm in software)?
>
[The former would be hard to change but the latter should be relatively easy]

Are you looking for something like this:
https://en.wikipedia.org/wiki/RC-5
 Years ago  a long range remote used IR leds which could take 1A
current, but only for a microsecond or so.  Microsecond pulses were
modulated with 33-38kHz "carrioer" and that was keyed with data,
around 1-2kHz.
There are dedicated deceiver modules which  can output that data

Such as:
https://cdn-shop.adafruit.com/datasheets/tsop382.pdf
They do all the analogue processing and just output a datastream to the decoder.
Typically the bitstream runs about 1kbit/s so easily decoded by software.
The transmitter can also be handled by driving an LED from a timer programmed to output the 38kHz then doing on-off keying (OOK) to provide the modulation. Minimal hardware outside a microprocessor is required.
kw