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 (http://davehouston.org). 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.

5759

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. (http://en.wikipedia.org/wiki/KeeLoq)

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 (http://www.picbasic.co.uk/forum/showthread.php?t=198&page=1). 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 (http://en.wikipedia.org/wiki/Manchester_code).

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