binary input from analog potentiometer?

Other Hardware Sensors
4 
const int threshold = 127;
const int center = 1023/2;

const uint8_t xPin = A2;
const uint8_t yPin = A1;

void loop() {
  int xVal = analogRead (xPin);
  int yVal = analogRead (yPin);

  if (xVal < (center - threshold)) { // Left
    ; // left key does nothing in main menu
  }
  if (xVal > (center + threshold)) { // Right
    ; // right key does nothing in main menu
  }

  if (yVal < (center - threshold)) { // Down
    mode_select--;
    if (mode_select < 1)         // wrap around menu
      mode_select = numModes;
  }
  if (yVal > (center + threshold)) { // Up
    mode_select++;
    if (mode_select > numModes)  // wrap around menu
      mode_select = 1;
  }
}

Pieter