Help on momentary push switches in series.

Other Hardware General Electronics
20

I think this is a more generic solution:

#define KEY_1 0x01 //key1
#define KEY_2 0x02 //key2
#define KEY_3 0x04 //key3
...

//macro to read 6 keys
#define adcKeyscan6(pin)  ((analogRead(pin) + 2) >> 4)

  key_pressed = adcKeyscan6(BUTTON_PIN1); //read button_pin1
  if (key_pressed & KEY_1) {
    //key_1 pressed, do something
  }

  if (key_pressed & (KEY_2 | KEY_3)) {
    //key_2 or key_3 pressed, do something else
  }

  if ((key_pressed & KEY_4) | (key_pressed & KEY_5)) {
    //key4 and key_5 pressed. 
  }
  ...

You can expand it to read more or less pins. It assumes 10-bit adc and buttons are pulled to Vref.