Viable debounce button?

Hardware MKR Family MKRGSM1400
1

Working fine, but is it ok?
Not using millis().

Any input?

void defDI() {  pinMode(MKR_BTN, INPUT_PULLUP); }

uint8_t buttonPoll()
{
static uint8_t mBTNout=0;
static uint8_t cy=0;
if (!digitalRead(MKR_BTN)) {  if (cy>=20)   {    mBTNout=1;    cy=0;  }  if (cy<=220) cy++;  } else { mBTNout=0; cy=0; } 

return mBTNout;
}

Complete code,

#define MKR_BTN A1    //BUTTON PIN.
String debugString = "";

void setup() {
  // put your setup code here, to run once:
defDI();
debugStart();
}

void loop() {
  // put your main code here, to run repeatedly:

uint8_t button = buttonPoll();
debugString = "BUTTON ";
if (button) debugString += "PRESSED";
if (!button) debugString += "NOT PRESSED";

debugPoll();

}

void defDI() {  pinMode(MKR_BTN, INPUT_PULLUP); }

uint8_t buttonPoll()
{
static uint8_t mBTNout=0;
static uint8_t cy=0;
if (!digitalRead(MKR_BTN)) {  if (cy>=20)   {    mBTNout=1;    cy=0;  }  if (cy<=220) cy++;  } else { mBTNout=0; cy=0; } 

return mBTNout;
}


void debugStart() { SerialUSB.begin(9600); }
void debugPoll() { 
 if (SerialUSB) {
    static uint32_t eee = 0;
    const uint8_t interval = 2;
    if (millis() - eee >= interval*200UL) { SerialUSB.print("\n >"); Serial.print(debugString); eee=millis(); }
  }
  if (SerialUSB.available())
  {
    uint8_t temp=0;
    char c=SerialUSB.read();
    switch (c)
    {  //INPUT FUNCTIONS, FOR DEBUGGING.
      case 'A':
      SerialUSB.print("\nA:");
      
    }
  }

}
2

Figuring your code takes about 1ms to run then you have to hold the button for a time longer than 20ms to engage it. I'm not sure why you have it counting up to 220 since it is not necessary. If there is bad or noisy contact then your code allows it to return to "1" instantly and restart the 20ms countdown. What you need for debounce is a latch to hold the data in a triggered state until you have serviced the button push. If your button develops corroded contacts with time it will probably not work as it does new. Consider an operator with a slow finger. You might be better off using a pin assigned to an interrupt. Disable the interrupt while servicing the button push and enable it again afterwards.