Thanks for all the tips. Here is what I've done and what happened:


"Measure the current from INT1 to Ground, using a meter."

Done. If I only connect the meter between P3.3 and Gnd the current is 0. (I'm not sure, it's difficult to measure. Using a resistor I can reach the connections better with the meter.)
But the current from P3.3 to the output of the AND is about 4.5 mA (through the resistor, voltage drop is 210 mV with a 47 ohm resistor).


"Is it possible that a static discharge to the P3.3 pin while you were wiring the circuit either caused CMOS latchup of the microcontroller OR simply blew away your INT1 input?"

I don't think so, because I first wired the circuit and then put in the chip.


"Is the P3.3 level at a constant 2.3 V level when you keep the pushbutton pressed?. Are you sure there is not a square waveform at that pin?"

Constant level, no wave ...


"Connect a 470 ohm resistor between P3.3 and ground. If the voltage is still 2.3 V, your uC is probably damaged."

Done. Voltage stays at 2.3.


"BTW: Are you sure no AND-gate input is left unconnected?."

The AND is a dual 4-line gate. I connected Vcc and Gnd, 4 input lines, 1 output. The other 4 input lines and the corresponding output aren't connected yet. 2 pins of the DIL14 are unused and also unconnected.