diff --git a/README.md b/README.md
index cc2743a..dcce4e0 100644
--- a/README.md
+++ b/README.md
@@ -302,6 +302,15 @@ MuraxFast bypassed stages (0.55 DMIPS/Mhz) ->
 
 There is some scripts to generate the SoC and call the icestorm toolchain there : scripts/Murax/
 
+Note that now a toplevel simulation testbench with the same feature + a GUI is implemented with SpinalSim. You can find it in src/test/scala/vexriscv/MuraxSim.scala.
+
+To run it : 
+
+```sh
+#This will generate the Murax RTL + run its testbench. You need Verilator 3.9xx installated.
+sbt "test:runMain vexriscv.MuraxSim"
+```
+
 ## Build the RISC-V GCC
 
 In fact, now you can find some prebuild GCC : <br>
diff --git a/src/test/scala/vexriscv/MuraxSim.scala b/src/test/scala/vexriscv/MuraxSim.scala
index 5cc2637..375f8dd 100644
--- a/src/test/scala/vexriscv/MuraxSim.scala
+++ b/src/test/scala/vexriscv/MuraxSim.scala
@@ -1,21 +1,27 @@
 package vexriscv
 
+import java.awt
+import java.awt.event.{ActionEvent, ActionListener}
+
 import spinal.sim._
 import spinal.core._
 import spinal.core.sim._
 import vexriscv.demo.{Murax, MuraxConfig}
-import java.awt.Graphics
-import javax.swing.{JFrame, JPanel}
+import java.awt.{Color, Dimension, Graphics, GridLayout}
+import javax.annotation.processing.SupportedSourceVersion
+import javax.swing.{BoxLayout, JButton, JFrame, JPanel}
 
 import spinal.lib.com.jtag.sim.JtagTcp
 import spinal.lib.com.uart.sim.{UartDecoder, UartEncoder}
 
+import scala.collection.mutable
+
 
 
 object MuraxSim {
   def main(args: Array[String]): Unit = {
-//    def config = MuraxConfig.default.copy(onChipRamSize = 256 kB)
-    def config = MuraxConfig.default.copy(onChipRamSize = 4 kB, onChipRamHexFile = "src/main/ressource/hex/muraxDemo.hex")
+    def config = MuraxConfig.default.copy(onChipRamSize = 256 kB)
+//    def config = MuraxConfig.default.copy(onChipRamSize = 4 kB, onChipRamHexFile = "src/main/ressource/hex/muraxDemo.hex")
 
     SimConfig.allOptimisation.compile(new Murax(config)).doSimUntilVoid{dut =>
       val mainClkPeriod = (1e12/dut.config.coreFrequency.toDouble).toLong
@@ -25,7 +31,7 @@ object MuraxSim {
 
       val clockDomain = ClockDomain(dut.io.mainClk, dut.io.asyncReset)
       clockDomain.forkStimulus(mainClkPeriod)
-//      clockDomain.forkSimSpeedPrinter()
+//      clockDomain.forkSimSpeedPrinter(2)
 
       val tcpJtag = JtagTcp(
         jtag = dut.io.jtag,
@@ -43,28 +49,56 @@ object MuraxSim {
       )
 
 
-      val leds = fork{
+      val guiThread = fork{
+        val guiToSim = mutable.Queue[Any]()
+
         var ledsValue = 0l
         val ledsFrame = new JFrame{
-          setContentPane(new DrawPane());
-          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
-          setSize(400, 400);
-          setVisible(true);
-
-          //create a component that you can actually draw on.
-          class DrawPane extends JPanel{
+          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) {
-                if (((ledsValue >> i) & 1) != 0) {
-                  g.fillRect(20*i, 20, 20, 20)
+                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 JButton("Reset"){
+            addActionListener(new ActionListener {
+              override def actionPerformed(actionEvent: ActionEvent): Unit = {
+                println("ASYNC RESET")
+                guiToSim.enqueue("asyncReset")
+              }
+            })
+            setAlignmentX(awt.Component.CENTER_ALIGNMENT)
+          })
+          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
+          pack()
+          setVisible(true)
+
         }
 
         while(true){
-          sleep(mainClkPeriod*100000)
+          sleep(mainClkPeriod*50000)
+
+          val dummy = if(guiToSim.nonEmpty){
+            val request = guiToSim.dequeue()
+            if(request == "asyncReset"){
+              dut.io.asyncReset #= true
+              sleep(mainClkPeriod*32)
+              dut.io.asyncReset #= false
+            }
+          }
+
           ledsValue = dut.io.gpioA.write.toLong
           ledsFrame.repaint()
         }