diff --git a/src/test/scala/vexriscv/MuraxSim.scala b/src/test/scala/vexriscv/MuraxSim.scala
index 467cfdb..e8c53df 100644
--- a/src/test/scala/vexriscv/MuraxSim.scala
+++ b/src/test/scala/vexriscv/MuraxSim.scala
@@ -1,15 +1,13 @@
 package vexriscv
 
 import java.awt
-import java.awt.event.{ActionEvent, ActionListener}
+import java.awt.event.{ActionEvent, ActionListener, MouseEvent, MouseListener}
 
 import spinal.sim._
 import spinal.core._
 import spinal.core.sim._
 import vexriscv.demo.{Murax, MuraxConfig}
-import java.awt.{Color, Dimension, Graphics, GridLayout}
-import javax.annotation.processing.SupportedSourceVersion
-import javax.swing.{BoxLayout, JButton, JFrame, JPanel}
+import javax.swing._
 
 import spinal.lib.com.jtag.sim.JtagTcp
 import spinal.lib.com.uart.sim.{UartDecoder, UartEncoder}
@@ -53,25 +51,19 @@ object MuraxSim {
         val guiToSim = mutable.Queue[Any]()
 
         var ledsValue = 0l
+        var switchValue : () => BigInt = null
         val ledsFrame = new JFrame{
           setLayout(new BoxLayout(getContentPane, BoxLayout.Y_AXIS))
-          add(new JPanel{
-            val ledDiameter = 20
-            val blackThickness = 2
-            override def paintComponent(g : Graphics) : Unit = {
-              for(i <- 0 to 7) {
-                g.setColor(Color.BLACK)
-                val x = i*ledDiameter + 1
-                g.fillOval(x,1,ledDiameter,ledDiameter);
-                if (((ledsValue >> (7-i)) & 1) != 0) {
-                  g.setColor(Color.GREEN.darker())
-                  g.fillOval(x+blackThickness,3,ledDiameter-blackThickness*2,ledDiameter-blackThickness*2);
-                }
-              }
-              g.setColor(Color.BLACK)
-            }
-            this.setPreferredSize(new Dimension(ledDiameter*8+2, ledDiameter+2))
+          
+          add(new JLedArray(8){
+            override def getValue = ledsValue
           })
+          add{
+            val switches = new JSwitchArray(8)
+            switchValue = switches.getValue
+            switches
+          }
+
           add(new JButton("Reset"){
             addActionListener(new ActionListener {
               override def actionPerformed(actionEvent: ActionEvent): Unit = {
@@ -87,6 +79,12 @@ object MuraxSim {
 
         }
 
+        //Fast refresh
+        clockDomain.onSampling{
+          dut.io.gpioA.read #= (dut.io.gpioA.write.toLong & dut.io.gpioA.writeEnable.toLong) | (switchValue() << 8)
+        }
+
+        //Slow refresh
         while(true){
           sleep(mainClkPeriod*50000)
 
diff --git a/src/test/scala/vexriscv/Swing.scala b/src/test/scala/vexriscv/Swing.scala
new file mode 100644
index 0000000..261a79c
--- /dev/null
+++ b/src/test/scala/vexriscv/Swing.scala
@@ -0,0 +1,55 @@
+package vexriscv
+
+import java.awt.{Color, Dimension, Graphics}
+import java.awt.event.{MouseEvent, MouseListener}
+import javax.swing.JPanel
+
+abstract class JLedArray(ledCount : Int,ledDiameter : Int = 20, blackThickness : Int = 2) extends JPanel{
+  def getValue() : BigInt
+
+  override def paintComponent(g : Graphics) : Unit = {
+    val value = getValue()
+    for(i <- 0 to ledCount-1) {
+      g.setColor(Color.BLACK)
+      val x = i*ledDiameter + 1
+      g.fillOval(x,1,ledDiameter,ledDiameter)
+      if (((value >> (ledCount-1-i)) & 1) != 0) {
+        g.setColor(Color.GREEN.darker())
+        g.fillOval(x+blackThickness,3,ledDiameter-blackThickness*2,ledDiameter-blackThickness*2);
+      }
+    }
+    g.setColor(Color.BLACK)
+  }
+  this.setPreferredSize(new Dimension(ledDiameter*ledCount+2, ledDiameter+2))
+}
+
+class JSwitchArray(ledCount : Int,switchDiameter : Int = 20, blackThickness : Int = 2) extends JPanel{
+  var value = BigInt(0)
+  def getValue() = value
+  addMouseListener(new MouseListener {
+    override def mouseExited(mouseEvent: MouseEvent): Unit = {}
+    override def mousePressed(mouseEvent: MouseEvent): Unit = {}
+    override def mouseReleased(mouseEvent: MouseEvent): Unit = {}
+    override def mouseEntered(mouseEvent: MouseEvent): Unit = {}
+    override def mouseClicked(mouseEvent: MouseEvent): Unit = {
+      val idx = ledCount-1-(mouseEvent.getX-2)/switchDiameter
+      value ^= BigInt(1) << idx
+    }
+  })
+  override def paintComponent(g : Graphics) : Unit = {
+    for(i <- 0 to ledCount-1) {
+      g.setColor(Color.GRAY.darker())
+      val x = i*switchDiameter + 1
+      g.fillRect(x,1,switchDiameter,switchDiameter)
+      if (((value >> (ledCount-1-i)) & 1) != 0) {
+        g.setColor(Color.GRAY)
+      }else{
+        g.setColor(Color.GRAY.brighter())
+      }
+      g.fillRect(x+blackThickness,3,switchDiameter-blackThickness*2,switchDiameter-blackThickness*2);
+
+    }
+    g.setColor(Color.BLACK)
+  }
+  this.setPreferredSize(new Dimension(switchDiameter*ledCount+2, switchDiameter+2))
+}
\ No newline at end of file