Reverse engineering ELRO DB280 Doorbel

The ELRO DB280 is a doorbel system with a wireless remote. The system has a fixed code, although it can be changed quite easily by changing some "solder bridges"

We analyzed the wireless signal with an Logic analyzer and a 433 receiver.

The jumpers are set:

10000100

After analysing the pulses with the logic analyzer we do see the following

0001010101000101010101010

If we invert the set jumpers and we the code 1 character we see the following:

 0 1 1 1 1 0 1 1
0001010101000101010101010

We can conclude:

• Every pulse uses a 0 in front
• The code is inverted (or it's default up unless it's brought to the ground)
• There is a trailer: "010101010"