Re-coding a BX infra-red remote locking controller.

Introduction.

The remote control on a BX uses a TEA5500 chip for both the transmitter(TX) and receiver(RX).  Data on this device seems to be difficult to come by.  The Philips web site returns a 'device not found' on a search.  Some months ago someone posted a link to the data sheet and I downloaded it intending some day to work out just how to do the re-coding, that day has now come!

Programming

The device has 10 programming inputs and each input has 3 possible states, connected to the HIGH or LOW bus or, unusually, left unconnected.  This gives the possibility of 3^10 -2 combinations of code.

At manufacture all 10 program pins are connected to BOTH high and low busses.  The connecting links on the printed circuit boards (PCB) are drilled out at programming time. 

It should be a simple matter, therefore, to re-code either the receiver or the transmitter.  For reasons best known to Philips it's not as simple as it could be, the order of the pins is reversed and the logic levels have a peculiar quirk in that low on a transmitter becomes unconnected on the receiver and vice-versa!

On the pictures, for simplicity, I've marked the pins as A, B C etc, and the cut tracks yellow. 

What you need to do is draw up a table like this, which is the table for the pictures, filling in your own particular code.

The H, O, L refer to the pin connections  HIGH BUS, LOW BUS, OR OPEN

TX pin     LOGIC     LOGIC     RX pin
   A         L         O        K
   B         O         L        J
   C         H         H        H
   D         O         L        G
   E         H         H        F
   F         H         H        E
   G         L         O        D
   H         H         H        C
   J         O         L        B
   K         L         O        A

Note how H stays as H, but O becomes L and L becomes O

It's now a simple matter to make up any code you want, cut the PCB, (I used a 'Dremel' with a burr), to break the appropriate connection or connect by using wire link.  A word of warning when modifying the TX, the area marked as LOW BUS  has a protrusion on the plastic case in contact with it, some care is needed when re-fitting the PCB to the case.  This problem can be overcome by re-coding the receiver.

Disclaimer

This information is given in good faith and is based on work I have done. I can accept no responsibility if you use this information and fail, or worse still damage the TX or RX

Bob Smith 
March 2003

bob@rwbsmith.plus.com