I'm using and old multi purpose module with LCD, buzzer, key switch. The board is using 3 PCF8574 i2C IC
I could use the LCD, the problem is reading the key switch. The pins are always to a LOW level even when I set the pin to use the internal pullup.
// Set pinMode to OUTPUT
If I set the pin as an output and write a "HIGH" to it, I will get a HIGH level. The pin will always be at a LOW level when I set it to be an input. The board is a module and should be usable without modification to it by adding real pullup resistance.
Any idea on how to resolve the problem?