Simple control of the Pi-Lite HAT with Processing

basicpilite.pde

import processing.serial.*;

Serial port;
String portID = "/dev/ttyAMA0";

void setup() {
  size(100,100);
  background(255)
  port = new Serial(this,portID,9600);
}
void draw() {
  port.write("Hello world.");
  noLoop();
}