Android : android make button square

I have several Buttons inside a linear layout One of the buttons (sett) needs to be square however the height changes depending on the screen size and resolution

How to i make the width the same as the height?

the button in question is "@+id/sett"

My code is below

activity_activity1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/background2"
android:background="#EEEDEB"
android:layout_width="match_parent"
android:layout_height="match_parent"

android:orientation="vertical" >
<ImageView
    android:id="@+id/imageView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:adjustViewBounds="true"
    android:src="@drawable/sodexotop" />



    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:layout_marginLeft="15dp"
        android:layout_marginRight="15dp"
        android:background="#ffffff"
        android:gravity="center_horizontal"
        android:orientation="vertical" >

<Button
            android:id="@+id/Button01"
            android:layout_width="match_parent"
            android:layout_marginLeft="50sp"
            android:layout_marginRight="50sp"
            android:onClick="clk_fault"
            android:text="Enter Fault"
            android:textColor="#000000"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:layout_marginTop="10sp"
            android:background="@drawable/butt1"
            android:textSize="30sp" />

        <Button
            android:id="@+id/Button03"
            android:layout_width="match_parent"
            android:layout_marginLeft="50sp"
            android:layout_marginRight="50sp"
            android:onClick="clk_send"
            android:text="Send Data"
            android:textColor="#000000"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:layout_marginTop="10sp"
            android:background="@drawable/butt1"
            android:textSize="30sp" />

        <Button
            android:id="@+id/Button04"
            android:layout_width="match_parent"
            android:layout_marginLeft="50sp"
            android:layout_marginRight="50sp"
            android:onClick="clk_clear"
            android:text="Clear Data"
            android:textColor="#000000"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:layout_marginTop="10sp"
            android:background="@drawable/butt1"
            android:textSize="30sp" />



            <Button
                android:id="@+id/sett"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingLeft="10sp"
                android:paddingTop="10sp"
                android:paddingRight="10sp"
                android:paddingBottom="10sp"
                android:layout_marginTop="10sp"

                android:background="@drawable/butt1"
                android:onClick="clk_sett"
                android:text="S"
                android:textColor="#000000"
                android:textSize="50sp" />




         <Button
            android:id="@+id/exitbtn2"
            android:text="O"
            android:textColor="#000000"
            android:textSize="30sp"
            android:layout_width="60sp"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:layout_marginTop="10sp"
            android:background="@drawable/butt1"
            android:onClick="clk_exit" />
<TextView
        android:id="@+id/label_xxx3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:text=""
        android:layout_marginTop="10sp"
        android:textSize="10sp" />
    </LinearLayout>

<ImageView
    android:id="@+id/imageView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:adjustViewBounds="true"
    android:src="@drawable/sodexobottom" />
</LinearLayout>

Activity1.java

public class Activity1 extends Activity {
String BACK="";
public static Drawable myDrawable;
/** Called when the activity is first created. */
DBAdapter db;
final int ACTIVITY_CHOOSE_FILE = 1;
@Override
public void onStart()
{
    // RUN SUPER | REGISTER ACTIVITY AS INSTANTIATED IN APP CLASS
    super.onStart();
        App.Activity1 = this;
}   
 @Override
 public void onCreate(Bundle savedInstanceState) {
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,     WindowManager.LayoutParams.FLAG_FULLSCREEN);
    super.onCreate(savedInstanceState);
    getWindow().setFormat(PixelFormat.RGBA_8888);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_DITHER);
    setContentView(R.layout.activity_activity1);

    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    int h = metrics.heightPixels;
    int w = metrics.widthPixels;
    int w1 = (w/2);



    String testStringw = Integer.toString(w);
    String testStringh = Integer.toString(h);
    Button txt1 = (Button) findViewById(R.id.Button01);  
    Typeface font1 = Typeface.createFromAsset(getAssets(), "fonts/DistProTh.otf");  
    txt1.setTypeface(font1);
    Button txt2 = (Button) findViewById(R.id.Button03);        
    Typeface font2 = Typeface.createFromAsset(getAssets(), "fonts/DistProTh.otf");  
    txt2.setTypeface(font2);
    Button txt3 = (Button) findViewById(R.id.Button04);  
    Typeface font3 = Typeface.createFromAsset(getAssets(), "fonts/DistProTh.otf");  
    txt3.setTypeface(font3);
    Button txt4 = (Button) findViewById(R.id.sett);  
    Typeface font4 = Typeface.createFromAsset(getAssets(), "fonts/WebSymbols-Regular.otf");  
    txt4.setTypeface(font4);


    txt4.setLayoutParams(new LayoutParams(60, 60));




    Button txt5 = (Button) findViewById(R.id.exitbtn2);  
    Typeface font5 = Typeface.createFromAsset(getAssets(), "fonts/heydings_controls.ttf");  
    txt5.setTypeface(font5);



}

Any help is appreciated

Mark