diff --git a/.gitignore b/.gitignore
index 62e0404..e02c006 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,10 @@
 *.sch-bak
-*.kicad_pcb-bak
\ No newline at end of file
+*.kicad_pcb-bak
+
+*.o
+*.d
+
+software/arduino/.cproject
+software/arduino/.project
+software/arduino/.settings/
+.vscode/
diff --git a/.gitmodules b/.gitmodules
index 0c8c60b..c87a293 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -22,3 +22,6 @@
 [submodule "hardware/lib/biacco42_promicro"]
 	path = hardware/lib/biacco42_promicro
 	url = https://github.com/Biacco42/ProMicroKiCad.git
+[submodule "software/arduino/sim/matgui"]
+	path = software/arduino/sim/matgui
+	url = https://github.com/mls-m5/matgui
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..e0d31f0
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,3 @@
+
+all:
+	make -C software/arduino/keyboard
\ No newline at end of file
diff --git a/software/arduino/keyboard/Makefile b/software/arduino/keyboard/Makefile
index 9691cd9..caa3efb 100644
--- a/software/arduino/keyboard/Makefile
+++ b/software/arduino/keyboard/Makefile
@@ -2,7 +2,7 @@
 all: verify
 
 verify:
-	~/Prog/Program/arduino-1.8.9/arduino  --verify keyboard.ino | sed "s/stepper:/stepper.ino:/g"
+	~/Prog/Program/arduino-1.8.9/arduino  --verify keyboard.ino -v | sed "s/stepper:/stepper.ino:/g"
 	
 upload:
 	~/Prog/Program/arduino-1.8.9/arduino  --upload keyboard.ino | sed "s/stepper:/stepper.ino:/g"
diff --git a/software/arduino/keyboard/io.h b/software/arduino/keyboard/io.h
new file mode 100644
index 0000000..8099785
--- /dev/null
+++ b/software/arduino/keyboard/io.h
@@ -0,0 +1,65 @@
+/*
+ * io.h
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#pragma once
+
+#include "keyboardmap.h"
+#include "keyboardstate.h"
+#include "pins.h"
+
+// Standad layer
+const char *keyConfig1 = "§12345"
+                         "\tQWERT"
+                         "\177ASDFG"
+                         "\129<ZXCV"
+                         "\128\131\130   ";
+
+typedef KeyboardState<width, height> keyboard_state_t;
+keyboard_state_t state;
+
+KeyboardMap keyboardMap(width, height, keyConfig1);
+
+
+
+void setup() {
+  for (auto pin : xPins) {
+    pinMode(pin, OUTPUT);
+  }
+}
+
+//! Turn on one column pin and turn of the rest
+void changeColumnPin(size_t column) {
+  for (size_t i = 0; i < width; ++i) {
+    digitalWrite(xPins[i], i == column);
+  }
+}
+
+void readRowPins(keyboard_state_t &keyboardState, size_t x) {
+  for (size_t y = 0; y < height; ++y) {
+    int value = digitalRead(yPins[y]);
+    auto &keyState = keyboardState.state(x, y);
+
+    if (keyState != value) {
+      Serial.print("readRowPins: key is changed ");
+      Serial.print(x);
+      Serial.print(y);
+      keyboardMap.publishEvent(x, y, keyState);
+      keyState = value;
+    }
+  }
+}
+
+void loop() {
+  // Cycle through columns
+  for (size_t x = 0; x < width; ++x) {
+    changeColumnPin(x);
+
+    readRowPins(state, x);
+  }
+}
+
+
diff --git a/software/arduino/keyboard/keyboard.ino b/software/arduino/keyboard/keyboard.ino
index a9cfe27..493c7d6 100644
--- a/software/arduino/keyboard/keyboard.ino
+++ b/software/arduino/keyboard/keyboard.ino
@@ -1,27 +1,6 @@
-#include "keyboardmap.h"
-#include "keyboardstate.h"
-#include <array>
 
-namespace {
 
-const char *keyConfig1 = "§12345"
-                         "\tQWERT"
-                         "\177ASDFG"
-                         "\129<ZXCV"
-                         "\128\131\130   ";
-
-constexpr size_t width = 6;
-constexpr size_t height = 5;
-
-const std::array<char, width> xPins = {};
-const std::array<char, height> yPins = {};
-
-typedef KeyboardState<width, height> keyboard_state_t;
-keyboard_state_t state;
-
-KeyboardMap keyboardMap(width, height, keyConfig1);
-
-} // namespace
+#include "io.h"
 
 void writeKeyRelease(char key) {
   // Implement this
@@ -29,39 +8,4 @@ void writeKeyRelease(char key) {
 
 void writeKeyPress(char key) {
   // Implement this
-}
-
-void setup() {
-  for (auto pin : xPins) {
-    pinMode(pin, OUTPUT);
-  }
-}
-
-//! Turn on one column pin and turn of the rest
-void changeColumnPin(size_t column) {
-  for (size_t i = 0; i < xPins.size(); ++i) {
-    digitalWrite(xPins[i], i == column);
-  }
-}
-
-void readRowPins(keyboard_state_t &keyboardState, size_t x) {
-  for (size_t y = 0; y < yPins.size(); ++y) {
-    int value = digitalRead(yPins[y]);
-    auto &keyState = keyboardState.state(x, y);
-
-    if (keyState != value) {
-      keyboardMap.publishEvent(x, y, keyState);
-      Serial.print("key is changed");
-      keyState = value;
-    }
-  }
-}
-
-void loop() {
-  // Cycle through columns
-  for (size_t x = 0; x < width; ++x) {
-    changeColumnPin(x);
-
-    readRowPins(state, x);
-  }
-}
+}
\ No newline at end of file
diff --git a/software/arduino/keyboard/keyboardstate.h b/software/arduino/keyboard/keyboardstate.h
index b20b373..e05c749 100644
--- a/software/arduino/keyboard/keyboardstate.h
+++ b/software/arduino/keyboard/keyboardstate.h
@@ -1,10 +1,8 @@
 #pragma once
 
-#include <array>
-
 template <size_t width, size_t height>
 class KeyboardState {
-  std::array<char, width*height> _state = {};
+  char _state[width * height] = {};
 
 public:
   typedef char state_t;
diff --git a/software/arduino/keyboard/pins.h b/software/arduino/keyboard/pins.h
new file mode 100644
index 0000000..b5995c4
--- /dev/null
+++ b/software/arduino/keyboard/pins.h
@@ -0,0 +1,17 @@
+/*
+ * pins.h
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#pragma once
+
+constexpr size_t width = 6;
+constexpr size_t height = 5;
+
+const char xPins[width] = {1, 2, 3, 4, 5, 6};
+const char yPins[height] = {8, 9, 10, 11, 12};
+
+
+
diff --git a/software/arduino/sim/Matmakefile b/software/arduino/sim/Matmakefile
new file mode 100644
index 0000000..9a0925e
--- /dev/null
+++ b/software/arduino/sim/Matmakefile
@@ -0,0 +1,18 @@
+# using matmake
+# https://github.com/mls-m5/matmake
+
+config +=
+	debug
+	c++14
+
+includes +=
+	../keyboard
+	
+sysincludes +=
+	matgui/include
+
+sim.src = *.cpp
+
+sim.src += matgui/src/*.cpp
+
+sim.libs += -lGL -lSDL2 -lSDL2_image
\ No newline at end of file
diff --git a/software/arduino/sim/keyboard.cpp b/software/arduino/sim/keyboard.cpp
new file mode 100644
index 0000000..55fe9ee
--- /dev/null
+++ b/software/arduino/sim/keyboard.cpp
@@ -0,0 +1,19 @@
+/*
+ * keyboard.cpp
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#include <iostream>
+using namespace std;
+
+void writeKeyRelease(char key) {
+    cout << "Key released " << key << endl;
+}
+
+void writeKeyPress(char key) {
+    cout << "keyboard.cpp: key pressed " << key << ", " << static_cast<unsigned>(key) << endl;
+}
+
+
diff --git a/software/arduino/sim/main.cpp b/software/arduino/sim/main.cpp
new file mode 100644
index 0000000..e45a179
--- /dev/null
+++ b/software/arduino/sim/main.cpp
@@ -0,0 +1,59 @@
+/*
+ * main.cpp
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#include "keys.h"
+
+#include "matgui/application.h"
+#include "matgui/window.h"
+#include "matgui/button.h"
+
+// Simulator
+#include "simio.h"
+#include "keyboardwritefunctions.h"
+
+// The code
+#include "io.h"
+
+#include <iostream>
+
+using namespace std;
+using namespace MatGui;
+
+int main(int argc, char **argv) {
+    Application app(argc, argv);
+
+    Window window("keyboard simulator");
+
+    setup();
+
+    for (size_t y = 0; y < height; ++y) {
+        auto layout = make_unique<LinearLayout>();
+        layout->orientation(LayoutOrientation::LAYOUT_HORIZONTAL);
+        for (size_t x = 0; x < width; ++x) {
+            auto button = make_unique<Button>("hej");
+            button->pointerDown.connect([x, y](Button::PointerArgument arg) {
+                cout << "clicked " << x << ", " << y << endl;
+                simio::setSimKey(x, y, true);
+            });
+            button->pointerUp.connect([x, y](Button::PointerArgument arg) {
+                cout << "main.cpp: released " << x << ", " << y << endl;
+                simio::setSimKey(x, y, false);
+            });
+            layout->addChild(std::move(button));
+        }
+        window.addChild(std::move(layout));
+    }
+
+    window.frameUpdate.connect([]() {
+        loop();
+    });
+
+    app.mainLoop();
+}
+
+
+
diff --git a/software/arduino/sim/matgui b/software/arduino/sim/matgui
new file mode 160000
index 0000000..1b6ba9f
--- /dev/null
+++ b/software/arduino/sim/matgui
@@ -0,0 +1 @@
+Subproject commit 1b6ba9f2d5b2954975eac090895a32e5c3a51027
diff --git a/software/arduino/sim/sim b/software/arduino/sim/sim
new file mode 100755
index 0000000..e3d66c9
Binary files /dev/null and b/software/arduino/sim/sim differ
diff --git a/software/arduino/sim/simio.cpp b/software/arduino/sim/simio.cpp
new file mode 100644
index 0000000..a06c640
--- /dev/null
+++ b/software/arduino/sim/simio.cpp
@@ -0,0 +1,59 @@
+/*
+ * simio.cpp
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#include "simio.h"
+#include <array>
+#include "pins.h"
+#include <algorithm>
+
+using namespace simio;
+
+namespace {
+
+std::array<uint8_t, 255> pinState = {};
+std::array<uint8_t, width * height> simKeyState = {};
+
+auto getSimKey(size_t x, size_t y) {
+    return simKeyState.at(x + y * width);
+}
+
+} // namespace
+
+void digitalWrite(uint8_t pin, uint8_t value) {
+    pinState.at(pin) = value;
+}
+
+
+int digitalRead(uint8_t ypin) {
+    auto found = std::find(yPins, yPins + height, ypin);
+    if (found == yPins + height) {
+        throw "not a valid input pin";
+    }
+    size_t y = found - yPins;
+    for (int x = 0; x < width; ++x) {
+        if (getSimKey(x, y) * pinState.at(xPins[x])) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void pinMode(uint8_t pin, uint8_t mode) {
+    // Does not make so much sense with
+}
+
+namespace simio {
+
+void setSimKey(size_t x, size_t y, uint8_t state) {
+    simKeyState.at(x + y * width) = state;
+}
+
+}
+
+
+
diff --git a/software/arduino/sim/simio.h b/software/arduino/sim/simio.h
new file mode 100644
index 0000000..5d2dd60
--- /dev/null
+++ b/software/arduino/sim/simio.h
@@ -0,0 +1,49 @@
+/*
+ * simio.h
+ *
+ *  Created on: 3 mars 2020
+ *      Author: Mattias Larsson Sköld
+ */
+
+#pragma once
+
+#include <iostream>
+
+#define HIGH 0x1
+#define LOW  0x0
+
+#define INPUT 0x0
+#define OUTPUT 0x1
+#define INPUT_PULLUP 0x2
+
+#define PI 3.1415926535897932384626433832795
+#define HALF_PI 1.5707963267948966192313216916398
+#define TWO_PI 6.283185307179586476925286766559
+#define DEG_TO_RAD 0.017453292519943295769236907684886
+#define RAD_TO_DEG 57.295779513082320876798154814105
+#define EULER 2.718281828459045235360287471352
+
+static class SerialPort {
+public:
+
+    template <class T>
+    void print(const T& value);
+
+} Serial;
+
+void digitalWrite(uint8_t pin, uint8_t value);
+int digitalRead(uint8_t pin);
+void pinMode(uint8_t pin, uint8_t mode);
+
+template<class T>
+inline void SerialPort::print(const T& value)
+        {
+    std::cout << value << std::endl;
+}
+
+namespace simio {
+
+void setSimKey(size_t x, size_t y, uint8_t state);
+
+}
+