add keyboard source code

Code/uconsole_keyboard/tickwaiter.h

@@ -0,0 +1,30 @@
+#ifndef TICKWAITER_H
+#define TICKWAITER_H
+
+#include <cstdint>
+#include "math.h"
+
+template<uint32_t TargetInterval>
+class TickWaiter {
+  public:
+    uint8_t waitForNextTick() {
+      const auto last = this->last;
+      const auto now = millis();
+      this->last = now;
+
+      const auto delta = getDelta(last, now, 255);
+
+      if (delta >= TargetInterval) {
+        return delta;
+      }
+
+      delay(TargetInterval - delta);
+
+      const auto now2 = millis();
+      return getDelta(last, now2, 255);
+    }
+  private:
+    uint32_t last = 0;
+};
+
+#endif