/* -*- tab-width: 4 -*-
*
* Electric(tm) VLSI Design System
*
* File: AmpsVsVolts.java
* Written by Tom O'Neill, Sun Microsystems.
*
* Copyright (c) 2005 Sun Microsystems and Static Free Software
*
* Electric(tm) is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* Electric(tm) is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Electric(tm); see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, Mass 02111-1307, USA.
*/
package com.sun.electric.tool.simulation.test;
import java.io.PrintWriter;
/**
* Measures current as a function of voltage, writing results to file. The user
* is free to change any of the member variables at any time, in order to
* perform a measurement with different characteristics.
*/
public class AmpsVsVolts {
/** Power supply channel supplying the voltage. */
public PowerChannel supply;
/** Current measurement device */
public CurrentReadable ammeter;
/** Minimum voltage in sweep, in Volts */
public float voltsMin = 0.f;
/**
* Maximum voltage in sweep, in Volts. Must be greater than
* <code>voltsMin</code>
*/
public float voltsMax = 2.001f;
/** Voltage step size in Volts, must be greater than zero */
public float voltsStep = 0.2f;
/** Number of seconds between voltage setting and current reading */
public float settleTime = 1.f;
/**
* Specifies a current vs voltage measurement using the default voltage
* range and <code>settleTime</code>.
*
* @param supply
* Power supply channel supplying the voltage
* @param ammeter
* Current measurement device
*/
public AmpsVsVolts(PowerChannel supply, CurrentReadable ammeter) {
this.supply = supply;
this.ammeter = ammeter;
}
/**
* Specifies a current vs voltage measurement.
*
* @param supply
* Power supply channel supplying the voltage
* @param ammeter
* Current measurement device
* @param voltsMin
* Minimum voltage in sweep, in Volts
* @param voltsMax
* Maximum voltage in sweep, in Volts
* @param voltsStep
* Voltage step size in Volts, must be greater than zero
* @param settleTime
* Number of seconds between voltage setting and current reading
*/
public AmpsVsVolts(PowerChannel supply, CurrentReadable ammeter,
float voltsMin, float voltsMax, float voltsStep, float settleTime) {
if (voltsMax < voltsMin || voltsStep < 0.f) {
Infrastructure.fatal("Voltage min=" + voltsMin + ", max="
+ voltsMax + ", step=" + voltsStep
+ ". Require max>min and step>0");
}
this.supply = supply;
this.ammeter = ammeter;
this.voltsMin = voltsMin;
this.voltsMax = voltsMax;
this.voltsStep = voltsStep;
this.settleTime = settleTime;
}
/**
* Write the IV curve specified by this object to the provided file. At end,
* sets voltage to 0 V.
*
* @param file
* File to write the IV curve to
*/
public void measure(PrintWriter file) {
file.println("# (volts, amps) samples");
for (float volts = voltsMin; volts < voltsMax; volts += voltsStep) {
supply.setVoltageWait(volts);
try { Thread.sleep( (int)(1000*settleTime) ); } catch (InterruptedException _) { }
float amps = ammeter.readCurrent();
System.out.println(volts + " V: " + amps + " A");
file.println(volts + " " + amps);
}
supply.setVoltageWait(0.f);
}
/** Unit test */
public static void main(String[] args) {
}
}