package rc_meassure;

import com.pi4j.io.gpio.GpioController;
import com.pi4j.io.gpio.GpioFactory;
import com.pi4j.io.gpio.GpioPinDigitalInput;
import com.pi4j.io.gpio.GpioPinDigitalOutput;
import com.pi4j.io.gpio.Pin;
import com.pi4j.io.gpio.PinState;
import com.pi4j.io.gpio.RaspiPin;
import static java.lang.Math.pow;
import java.util.concurrent.TimeUnit;

/**
 *
 * In einer echten Java Anwendung würde man das nicht so machen, das dient wirklich nur als Beispiel.
 */
public class RC_meassure {

    /**
     * @param args the command line arguments
     */
    static Pin rcPin = RaspiPin.GPIO_00;
    static final int r = 100000;
    static final float c = (float) (100 * pow(10, -9));
    /**
     * Vih = 0.625*Vdd
     * http://www.farnell.com/datasheets/1835725.pdf
     */
    static final float vih = (float) 2.976473;
    public static void main(String[] args) throws InterruptedException {
        GpioController gpio = GpioFactory.getInstance();
        gpio.unexportAll();
        final GpioPinDigitalOutput outPin = gpio.provisionDigitalOutputPin(rcPin);
        outPin.setShutdownOptions(true, PinState.LOW);
        outPin.low(); //Entlade Kondensator;
        
        TimeUnit.SECONDS.sleep(1);       
        //gpio.shutdown(); 
        gpio.unprovisionPin(outPin);
        
        long startTime = System.nanoTime();
        final GpioPinDigitalInput inPin = gpio.provisionDigitalInputPin(rcPin);
        
        while(inPin.isLow()){ //warte
            
        }
        long estimatedTime = System.nanoTime() - startTime;
        gpio.unprovisionPin(inPin);
        System.out.println(estimatedTime); 
        System.out.println("Voltage: " + meassureRCVoltage(estimatedTime, r, c, vih));
    }
    static float meassureRCVoltage(long t, float r, float c, float vih_voltage){
        float vbat = (vih_voltage * c * r) /((float)(t * pow(10, -9)));
        return vbat;
    }
}