Wednesday, December 15, 2010

Using the Codec-Adaptative Wireless Relay with the 315Mhz Wireless Car Key Fob

I recently bought the Codec-Adaptative Wireless Relay

And the 315Mhz Wireless Car Key Fob

Luckly they work together. And quite well. As soon as you get yours, all you need to learn how to use them is to plug the 12 V DC power source to the Relay.

You can't program the Key Fob, but you have to program the Relay.

1. Choose the operation mode for the Relay:

A. Latch – Connect pin 1 and 2 – all memorized signals toggles the relay state.
B. Interlock – Connect pin 2 and 3 – some signals activates the relay, while other signals deactivates it.
C. Non-latch – Empty – the relay remains in a normal state except when it is receiving a expected signal. As soon as the signal reception is interrupted, the relay returns to its normal state.

2. You can clear all memorized signals by pressing the programming button until the led goes off.
3. You can add program new signals by pressing the programming button and then sending the signal.

The key fob emits different signals for each button and button combination. So button 1 sends a different signal than button 2, and both signals are different from pressing button 1 and 2 together. A single key fob can emit up to 16 different signals, but due to hardware limitations you can only use 15 of these, by pressing button combinations.

Two key fobs are unlikely to emit the same signals, as the main component (HS1527) datasheet states that it uses a 20 bit random salt for its signals. That means that you can have up to 1M (1,048,576) different key fobs.

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