Arduino code:

• pinMode(GPIO, OUTPUT);
  
• digitalWrite(GPIO, STATE);
  

• pinMode(GPIO, INPUT);
  
• digitalRead(GPIO);
  

The following modes are supported for the basic input and output:

• INPUT sets the GPIO as input without pullup or pulldown (high impedance).
• OUTPUT sets the GPIO as output/read mode.
• INPUT_PULLDOWN sets the GPIO as input with the internal pulldown.
• INPUT_PULLUP sets the GPIO as input with the internal pullup.