Probably, the hardest part of this project is to figure out how your remote control works.



As Dave Jones says, "don't turn it on, take it apart!". Open up the case on your remote control. I hope your's is as easy as mine, it just had 3 screws. Look carefully at the board on your controller and find where the buttons are, most likely they are traces on the PCB activated by rubber button. Follow the traces connected to the button, there should be 2 connections to each button. One side of the button will be connected to a chip on the board (it will either be a black rectangle with legs, or a black plastic blob), the other end will be connected through a resistor to either the battery + or the battery -.



In my case, the buttons were connected to the + of the battery. This means that the button "pulls up" the micrcontroller line to the supply voltage when it is pressed. To emulate the press of a button, we will connect the GPIO of the Raspberry pi through a resistor to the of the button that is connected to the chip on the board (rectangle or blob).



The first schematic shows how the buttons were connected on my remote. The second schematic show how to inject the signal from the Raspberry Pi.



I created a board to make this as small as possible and be able to add the extra hardware into the case for the remote. The layout for the board is included. I used surface mount resistors because I had some, also the values aren't that important, 330 Ohm - 1K Ohms would be good choices. If you have different values and through hole resistors, that's fine, it will work fine. Also, creating a custom board for this is not required, you can certainly solder resistors directly to the remote's board. (good luck :))