On/Off led with RF Link and 16F628

[gingomkc]

Hi at all, i write because i have an question.
It's possible view an example that explaining as turn on and off a led with a RF receiver 433MHz connected for example at the pin RB5 of an pic 16F628??
I own a remote control that generates a signal (i presume) manchester.
Is there any example on this?

Thanks at all.

Gingomkc

[dhouston]

Take a look at my web page. There are a few articles there that you should find useful. Trying to control an LED without capturing/decoding the RF signal is problematic - depending on the type of RF receiver (e.g. superheterodyne or superregenerative) the output may be extremely noisy, meaning your LED would be on at all times. Read through a few articles there and then you should be able to formulate a more specific question. BTW, only a few RF remote codes use manchester coding - most are OOK.

[gingomkc]

Thank dhouston for your reply. I'm looking at on your site that recommended.

So i did some measurements with the oscilloscope, and the output pin of the receiver (AC-RX2-Aurel CS) i have this signal.

Remote control signal.txt

The signals are 2 because the remote has 2 channels.
What kind of encryption is it?
How do i implement a decoder in the pic?

Thanks

Fabbri Mattia

[dhouston]

Hmm - after me saying manchester encoding is rare, you seem to have a manchester encoded signal.

However, that particular receiver used the Microchip KeeLoc decoder chips (with encoders on the transmitters).and I cannot help you decode it. Even if you could decode it, KeeLoq practices code-hopping (sorta like serial monogamy) with the code changing with each transmission, so you would have spent a lot of time and effort for nothing. You can read about KeeLoq here.

If you follow the link in the references, there's one that claims they can break it with access to the remote (even near proximity) and drive away in your car after a few hours.

[gingomkc]

Thanks dhouston for the answer.
I'm sorry if i insist again, my idea was to store any code from an RF receiver connected to a pin anywhere on the pic, save it in the pic and then later compare what i get with what i have stored.
The problem is that i can not understand how to distinguish the 0 to 1.
You can do this?

Thanks

[dhouston]

Try searching the forum on manchester code. There's a transition in the middle of the bit period. Its direction determines 1 or 0.

   _          _
1=| |_   0=|_|

or vice versa - which is 1 and which is 0 is arbitrary.

There's usually a series of pulses without spaces to denote the start of a code.

However, if the codes use KeeLoq, you'll never see the same code twice so storing for comparison with later codes is a waste of time and effort..

[dhouston]

Wikipedia has better pictures and a description of manchester codes.

The widest pulse or space equals 1 bit period. The shortest pulse or space equals 1/2 bit period. Find the middle of each bit period and check the transition.

[wiger123]

Thanks dhouston for the answer.
I'm apologetic if i assert again, my abstraction was to abundance any cipher from an RF receiver affiliated to a pin anywhere on the pic, save it in the pic and again after analyze what i get with what i accept stored.
The botheration is that i can not accept how to analyze the 0 to 1.
You can do this?

[Ramius]

Not sure if this will be of any benefit to your project and you may wish to look at: http://www.rentron.com/PicBasic/RemoteControl.htm

Best, Ed