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Old 04-19-2022, 02:10 PM   #5
Dannyx's Avatar
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
Red face Re: Using car key fob as generic remote control

After doing some more reading, I learned (or rather inferred) some more about this particular PCF chip, despite the info being very scarce. It's quite complex. Inside the key fob, the chip isn't actually transmitting anything itself (i.e. it doesn't drive the antenna directly): instead, it "hands off" whatever data needs transmitting to a dedicated transmitter chip, which is what actually does the transmitting.

The PCF chip also handles the immobilizer part, which prevents the car from starting if the key is turned in the barrel, but the fob is not actually IN the barrel. I actually confirmed this myself a while back when I replaced the shell of my fob and tried giving it a turn without the board in the shell: the engine started for a second, but it immediately turned off. I don't care about that part at all and I probably don't care about the encrypted part of the 433Mhz message either - all I want is to pick up the "payload" (?) and work out what button was pushed.

I found something HERE, but again, I'm not sure if it'd work with my particular fob. I need to get myself a receiver and actually try it. I imagine it should pick up SOMETHING at least (it IS 433Mhz after all), even if the info would be encrypted/incomplete. It's not an issue, because as the guy said in the end of his article, we don't care about that data anyway because we don't want to interact with the car itself...
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