ATtiny84 enable pullup resistors

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  • If PORTxn is written logic one when the pin is configured as an input pin, the pull-up resistor is activated.
  pinMode(PB0,INPUT);     // set PB0 as input
  digitalWrite(PB0,HIGH); // enable the internal pull-up resistor
  • If PORTxn is written logic one when the pin is configured as an output pin, the port pin is driven high (one).