I am developing a BMS Lighting/weather control system for building automation using 89c52. Currently, 6 x 6 matrix for keyboard is designed for mechanical pushbutton switches, and it works like a normal matrix keyboard with key-press connecting the scan lines of the matrix. 0 is output on column limbs, and row limbs are scanned. when a pushbutton is depressed, I get a low when I scan, and I will know what key is pressed.

Now, I have converted it into a touch switch panel - using body noise. Instead of a physical connection, I get a zero or 1 from my switch PCB, and I can invert this behaviour if required - 0 for on or 0 for off. I need to use the existing matrix scanning along with the new touch panel. ie: when I touch I get a zero or 1, and this has to be used to replace the pushbutton connection. What is the best method in this case?

I was planning to use a mosfet or a transistor to replace the pushbutton. Using the high signal from the touch switch, I will drive a transistor. Transistor emitter will be connected to the column limb which will have 0 (ground). So the transistor should ideally pull the micro's pin to ground. Or rather, a mosfet. Using a mosfet, I don't have to worry about collector not having a high. ie: switching ground should be more reliable with a mosfet , is this right?

Kindly suggest some method for my scheme.