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Garage door opener for 2 doors with 8 remotes
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ozcar:

--- Quote from: voltsandjolts on April 03, 2020, 01:02:20 pm ---
--- Quote from: ozcar on April 02, 2020, 08:46:53 pm ---Not sure what you mean about "fobs with different identities".

--- End quote ---

IIRC Keeloq fob ICs (HCS301 etc) have a crypt secrect code (encyption key derived from a secret manufacturer code*) and the fob 'serial' number.

* All of your system components must use a key derived from the manufacturer secret code.
This is what allows them to charge an-arm-and-a-leg for a new button remote.
With the code at my link above you become the manufacturer, with your own secret code.

--- End quote ---

Well, yes, I know that, but...

Swake mentioned difficulty finding fobs with different identities. For ones using Keeloq, the identity would be the serial number, and I would have thought that it would be difficult to find fobs with the same serial number (except for the far-out possibility that I mentioned of a maker getting very lazy).

Nor do I know why fobs with the same identity would be useful, as that would surely make it difficult to erase one of them only from the receiver (besides the fact that using two fobs with the same identity on the same receiver could be problematic).

Of course, if you make your own receiver, then you are free to come up with some way to erase only one of the fobs. You don't have to make your own fobs, but you'd have to know, or be able to derive, the fob keys, or else reprogram the fobs (if possible) with your own keys. Well, for Keeloq classic you could totally cheat in the receiver, and just ignore the encrypted portion of the transmission (all you need to react to a button press is contained in the non-encrypted part). That would, of course, totally defeat the purpose of having a rolling/hopping code, but, would you believe it, I have found "universal" receivers that do exactly that.
Peabody:
My opener is very old, and it is triggered by shorting the two receiver terminals.  Long ago I replaced the original Sears remote with a third party addon which works the same way.  This has a fixed key which is set by dip switches on both transmitter and receiver, with no provision for multiple transmitters each with its own key.  Of course this is the old style - before rolling codes and such.  But up to a point it would be possible to use multiple transmitter/receiver pairs, each with its own key, with all of the receiver outputs in a wired-OR setup to trigger the door opener.  To disable one transmitter, you would just unplug, or change the key of, its receiver.  Anyway, the point is that if you're talking about three-buck arduinos as the receivers, it might be easier to just do multiple copies, one for each transmitter, instead of jumping through hoops making one of them super intelligent.  But that would depend on how the door opener is actually triggered.
voltsandjolts:

--- Quote from: ozcar on April 03, 2020, 07:48:57 pm ---You don't have to make your own fobs, but you'd have to know, or be able to derive, the fob keys, or else reprogram the fobs (if possible) with your own keys.

--- End quote ---

Just reprogram the fob HCS300/301 with your own manufacturer code and serial.
Then, of course, use the same manufacturer code in the Keeloq classic receiver code, which I linked above.
Job done.
ozcar:

--- Quote from: voltsandjolts on April 04, 2020, 08:21:25 am ---
Just reprogram the fob HCS300/301 with your own manufacturer code and serial.


--- End quote ---

The fact that you get to choose the fob serial numbers maybe makes it a bit easier to keep track of them. For example, you could give them a 5 character "name", using a 5-bit character set (enough for single-case alphabetic).
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