#define SENSOR_NET  PA0
#define SENSOR_CHG  PA1
#define KEY_BAT     PA4
#define KEY_NET     PA5
#define CHG_CTRL    PA6

void setup() {
  pinMode(SENSOR_NET, INPUT_PULLDOWN);
  pinMode(SENSOR_CHG, INPUT_PULLDOWN);
  
  pinMode(KEY_BAT, OUTPUT);
  pinMode(KEY_NET, OUTPUT);
  pinMode(CHG_CTRL, OUTPUT);

  digitalWrite(KEY_BAT, LOW);
  digitalWrite(KEY_NET, LOW);
  digitalWrite(CHG_CTRL, LOW);
}

void loop() {
  bool net_present = digitalRead(SENSOR_NET);
  bool battery_low = digitalRead(SENSOR_CHG);

  if (net_present) {
    digitalWrite(KEY_NET, HIGH);
    digitalWrite(KEY_BAT, LOW);
    
    if (battery_low) {
      digitalWrite(CHG_CTRL, HIGH);
    } else {
      digitalWrite(CHG_CTRL, LOW);
    }
  } 
  else {
    digitalWrite(KEY_NET, LOW);
    digitalWrite(KEY_BAT, HIGH);
    digitalWrite(CHG_CTRL, LOW);
  }

  delay(500); 
}