Difference between revisions of "PWM"

#!/bin/sh
#
# script to command imx pwm 
# usage : pwm_imx frequency duty 
#

if [ $# -lt 2 ] 
then
echo "Provide two arguments to this script !"
echo "pwm_imx frequency dutycycle"
exit 1
fi

SYS_DIR="/sys/class/pwm/pwm0/"
FREQUENCY=$1
DUTY=$2

DUTY=`(echo $DUTY | awk '{ print $1*10}')`

if [ ! -d "$SYS_DIR" ]; then
echo "Can't find /sys/ interface for PWM"
exit 1
fi

echo "Starting PWM"
echo 1 > $SYS_DIR/active

#SET FREQUENCY
echo $FREQUENCY > $SYS_DIR/frequency
echo "Setting PWM to $FREQUENCY Hz"

#SET DUTY CYCLE
echo $DUTY > $SYS_DIR/duty
echo "Setting DUTY to $2 %"

exit 0

import java.io.*;

public class Imxpwm {

	private FileReader activeReader;

	private FileWriter activeWriter;

	private FileReader frequencyReader;

	private FileWriter frequencyWriter;

	private FileReader periodReader;

	private FileWriter periodWriter;

	private FileReader dutyReader;

	private FileWriter dutyWriter;

	public boolean isActive() {
		try {
			int result = this.activeReader.read();
			if (result == 0) {
				return true;
			} else {
				return false;
			}
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
	}

	public void setActive(boolean active) {
		try {
			if (active) {
				this.activeWriter.write("1");
				this.activeWriter.flush();
			} else {
				this.activeWriter.write("0");
				this.activeWriter.flush();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public double getDuty() {
		try {
			return this.dutyReader.read()/10.0;
		} catch (Exception e) {
			e.printStackTrace();
			return -1.0;
		}
	}

	public void setDuty(double duty) {
		try {
			this.dutyWriter.write(Double.toString(duty * 10));
			this.dutyWriter.flush();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public int getFrequency() {
		try {
			return this.frequencyReader.read();
		} catch (Exception e) {
			e.printStackTrace();
			return -1;
		}
	}

	public void setFrequency(int frequency) {
		try {
			this.frequencyWriter.write(Integer.toString(frequency));
			this.frequencyWriter.flush();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public int getPeriod() {
		try {
			return this.periodReader.read();
		} catch (Exception e) {
			e.printStackTrace();
			return -1;
		}
	}

	public void setPeriod(int period) {
		try {
			// en µs
			this.periodWriter.write(Integer.toString(period));
			this.periodWriter.flush();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * @param frequency
	 * @param duty
	 * @param period
	 * @param active
	 */
	public Imxpwm(int frequency, int duty, boolean active) {

		try {
			activeReader = new FileReader("/sys/class/pwm/pwm0/active");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			activeWriter = new FileWriter("/sys/class/pwm/pwm0/active");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			frequencyReader = new FileReader("/sys/class/pwm/pwm0/frequency");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			frequencyWriter = new FileWriter("/sys/class/pwm/pwm0/frequency");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			periodReader = new FileReader("/sys/class/pwm/pwm0/period");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			periodWriter = new FileWriter("/sys/class/pwm/pwm0/period");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			dutyReader = new FileReader("/sys/class/pwm/pwm0/duty");
		} catch (Exception e) {
			e.printStackTrace();
		}
		try {
			dutyWriter = new FileWriter("/sys/class/pwm/pwm0/duty");
		} catch (Exception e) {
			e.printStackTrace();
		}
		this.setActive(active);
		this.setDuty(duty);
		this.setFrequency(frequency);
	}

	public static void main(String[] args) throws Exception {
		Imxpwm maPWM = new Imxpwm(50, 75, true);
		double d = 0.0;
		for (int j = 0; j < 100; j++) {
			for (int i = 5; i <= 999; i++) {
				d = i * 1.0 / 10.0;
				maPWM.setDuty(d);
			}
		}
		maPWM.setFrequency(500);
		maPWM.setPeriod(50000);
	}

}