First arduino code

software/arduino/keyboard/Makefile

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+
+all: verify
+
+verify:
+	~/Prog/Program/arduino-1.8.9/arduino  --verify keyboard.ino | sed "s/stepper:/stepper.ino:/g"
+	
+upload:
+	~/Prog/Program/arduino-1.8.9/arduino  --upload keyboard.ino | sed "s/stepper:/stepper.ino:/g"
+
+#test: testing.cpp stepper.ino
+#	c++ testing.cpp -std=c++14 -o test -g -pthread

software/arduino/keyboard/keyboard.ino

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+#include "keyboardstate.h"
+#include <array>
+
+namespace {
+
+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;
+
+} // namespace
+
+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) {
+      // Todo: Handle this
+      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);
+  }
+}

software/arduino/keyboard/keyboardstate.h

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+#pragma once
+
+#include <array>
+
+template <size_t width, size_t height>
+class KeyboardState {
+  std::array<char, width*height> _state = {};
+
+public:
+  typedef char state_t;
+
+  // Todo: Bounds check
+  state_t state(size_t x, size_t y) const { return _state[y * width + x]; }
+  state_t &state(size_t x, size_t y) { return _state[y * width + x]; }
+};