HT12E Pushbutton Switch Extension

We have already used the Holtek HT12E as an encoder in several previous projects, primarily for remote controls. This encoder is triggered by a Low level on the TE (Transmission Enable) input. The transmitted address (and optionally data) can be set on the A0–A7 and AD8–AD11 inputs, for instance using DIP switches (internal pull-up resistors are present). The trick is now to change the address at the same time by pressing a second button. This is possible if a diode is added to the circuit.