MemristorElm.java

/*    
    Copyright (C) Paul Falstad and Iain Sharp
    
    This file is part of CircuitJS1.

    CircuitJS1 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 2 of the License, or
    (at your option) any later version.

    CircuitJS1 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 CircuitJS1.  If not, see <http://www.gnu.org/licenses/>.
*/

package com.lushprojects.circuitjs1.client;

//import java.awt.*;
//import java.util.StringTokenizer;

class MemristorElm extends CircuitElm {
    double r_on, r_off, dopeWidth, totalWidth, mobility, resistance;
    public MemristorElm(int xx, int yy) {
	super(xx, yy);
	r_on = 100;
	r_off = 160*r_on;
	dopeWidth = 0;
	totalWidth = 10e-9; // meters
	mobility = 1e-10;   // m^2/sV
	resistance = 100;
    }
    public MemristorElm(int xa, int ya, int xb, int yb, int f,
			StringTokenizer st) {
	super(xa, ya, xb, yb, f);
	r_on = new Double(st.nextToken()).doubleValue();
	r_off = new Double(st.nextToken()).doubleValue();
	dopeWidth = new Double(st.nextToken()).doubleValue();
	totalWidth = new Double(st.nextToken()).doubleValue();
	mobility = new Double(st.nextToken()).doubleValue();
	try {
	    current = Double.parseDouble(st.nextToken());
	} catch (Exception e) {}
	resistance = 100;
    }
    int getDumpType() { return 'm'; }
    String dump() {
	return super.dump() + " " + r_on + " " + r_off + " " + dopeWidth + " " +
	    totalWidth + " " + mobility + " " + current;
    }

    Point ps3, ps4;
    void setPoints() {
	super.setPoints();
	calcLeads(32);
	ps3 = new Point();
	ps4 = new Point();
    }
	
    void draw(Graphics g) {
	int segments = 6;
	int i;
	int ox = 0;
	double v1 = volts[0];
	double v2 = volts[1];
	int hs = 2+(int) (8*(1-dopeWidth/totalWidth));
	setBbox(point1, point2, hs);
	draw2Leads(g);
	setPowerColor(g, true);
	double segf = 1./segments;

	// draw zigzag
	for (i = 0; i <= segments; i++) {
	    int nx = (i & 1) == 0 ? 1 : -1;
	    if (i == segments)
		nx = 0;
	    double v = v1+(v2-v1)*i/segments;
	    setVoltageColor(g, v);
	    interpPoint(lead1, lead2, ps1, i*segf, hs*ox);
	    interpPoint(lead1, lead2, ps2, i*segf, hs*nx);
	    drawThickLine(g, ps1, ps2);
	    if (i == segments)
		break;
	    interpPoint(lead1, lead2, ps1, (i+1)*segf, hs*nx);
	    drawThickLine(g, ps1, ps2);
	    ox = nx;
	}
	    
	doDots(g);
	drawPosts(g);
    }
    
    boolean nonLinear() { return true; }
    void calculateCurrent() {
	current = (volts[0]-volts[1])/resistance;
    }
    void reset() {
	dopeWidth = 0;
    }
    void startIteration() {
	double wd = dopeWidth/totalWidth;
	dopeWidth += sim.timeStep*mobility*r_on*current/totalWidth;
	if (dopeWidth < 0)
	    dopeWidth = 0;
	if (dopeWidth > totalWidth)
	    dopeWidth = totalWidth;
	resistance = r_on * wd + r_off * (1-wd);
    }
    void stamp() {
	sim.stampNonLinear(nodes[0]);
	sim.stampNonLinear(nodes[1]);
    }
    void doStep() {
	sim.stampResistor(nodes[0], nodes[1], resistance);
    }
    void getInfo(String arr[]) {
	arr[0] = "memristor";
	getBasicInfo(arr);
	arr[3] = "R = " + getUnitText(resistance, sim.ohmString);
	arr[4] = "P = " + getUnitText(getPower(), "W");
    }
    double getScopeValue(int x) {
	return (x == Scope.VAL_R) ? resistance : super.getScopeValue(x);
    }
    int getScopeUnits(int x) {
	return (x == Scope.VAL_R) ? Scope.UNITS_OHMS : super.getScopeUnits(x);
    }
    boolean canShowValueInScope(int x) {
	return x == Scope.VAL_R;
    }
    public EditInfo getEditInfo(int n) {
	if (n == 0)
	    return new EditInfo("Max Resistance (ohms)", r_on, 0, 0);
	if (n == 1)
	    return new EditInfo("Min Resistance (ohms)", r_off, 0, 0);
	if (n == 2)
	    return new EditInfo("Width of Doped Region (nm)", dopeWidth*1e9, 0, 0);
	if (n == 3)
	    return new EditInfo("Total Width (nm)", totalWidth*1e9, 0, 0);
	if (n == 4)
	    return new EditInfo("Mobility (um^2/(s*V))", mobility*1e12, 0, 0);
	return null;
    }
    public void setEditValue(int n, EditInfo ei) {
	if (n == 0)
	    r_on = ei.value;
	if (n == 1)
	    r_off = ei.value;
	if (n == 2)
	    dopeWidth = ei.value*1e-9;
	if (n == 3)
	    totalWidth = ei.value*1e-9;
	if (n == 4)
	    mobility = ei.value*1e-12;
    }
}