Arduino:Problems using A6 and A7 with push buttons - arduino

Question

I'm developing an Arduino project with push buttons. I need some action to be executed after a button is pressed. The problem is that whenever I use buttons on A6 and A7 pins, I get unexpected results like a button receives HIGH without being physically pressed. As long as I use digital pins with buttons, the code works just fine.
Could you please explain to me what may be the problem using A6 and A7 pins or maybe there is some tricky thing with these pins that I need to consider.
Thanks a lot!
Here is my code:
int buttonBack = A6;
int flagLeft, flagRight;
int eventBack;
int currentButtonStatus = 0;
unsigned long currentButtonStatusStart1;
unsigned long currentButtonStatusStart2;
unsigned long currentButtonStatusStart3;
const int delayFalse = 30;
const int delayLongSingleClick = 300;
const int delayDeltaDoubleClick = 200;
void setup() {
pinMode(buttonBack,INPUT);
}
void loop() {
int eventBack = changeButtonStatus();
if (eventBack > 0) {
if(eventBack == 1) { // single button press
flagLeft = 1; flagRight = 0;
// move motor to the left code goes here
}
if(eventBack == 4) {
// long button press
flagLeft = 0; flagRight = 1;
// move motor to the right code goes here
}
}
}
int changeButtonStatus() {
int event = 0;
int currentButtonClick = analogRead(buttonBack);
unsigned long timeButton = millis();
switch(currentButtonStatus) {
case 0:
if(currentButtonClick) {
currentButtonStatus = 1;
currentButtonStatusStart1 = millis();
} else {
}
break;
case 1:
if(currentButtonClick) {
if(timeButton - currentButtonStatusStart1 >= delayLongSingleClick) {
event = 3;
}
} else {
if(timeButton - currentButtonStatusStart1 < delayFalse) {
currentButtonStatus = 0;
event = 0;
} else if(timeButton - currentButtonStatusStart1 < delayLongSingleClick) {
currentButtonStatus = 2;
currentButtonStatusStart2 = millis();
} else {
currentButtonStatus = 0;
event = 4;
}
}
break;
case 2:
if(currentButtonClick) {
if(timeButton - currentButtonStatusStart2 < delayFalse) {
currentButtonStatus = 1;
} else {
currentButtonStatus = 3;
currentButtonStatusStart3 = millis();
}
} else {
if(timeButton - currentButtonStatusStart2 > delayDeltaDoubleClick) {
currentButtonStatus = 0;
event = 1;
}
}
break;
case 3:
if(currentButtonClick) {
} else {
if(timeButton - currentButtonStatusStart3 < delayFalse) {
} else {
event = 2;
currentButtonStatus = 0;
}
}
break;
}
return event;
}

Answer 1

A6 and A7 do not have GPIO capability. They can only be used as analog inputs which means that you will need to provide external pullups if you are attempting to emulate digital inputs with them.