diff --git a/CPP/CRTP/example/main.cpp b/CPP/CRTP/example/main.cpp
index 3039948..4bbbd67 100644
--- a/CPP/CRTP/example/main.cpp
+++ b/CPP/CRTP/example/main.cpp
@@ -1,14 +1,138 @@
+#include <memory>
 #include <iostream>
 
+// https://www.modernescpp.com/index.php/c-is-still-lazy
 
-struct  Shape
+//
+//  CRTP base class of pin
+//
+
+/*
+    avoiding virtual call (static polymorphism)
+*/
+
+template <typename Derived>
+struct PinBase
 {
-    
+    void set(bool logic)
+    {
+        static_cast<Derived*>(this)->setImp(logic);
+    }
+
+    void toggle()
+    {
+        static_cast<Derived*>(this)->toggleImp();
+    }
+
+    bool get(void)
+    {
+        return static_cast<Derived*>(this)->getImp();
+    }
+
+    private:
+
+    //
+    // base implementations
+    //
+
+    void setImp()
+    {
+        std::cout << "base implementation of set()!" << std::endl;
+    }
+
+    void toggleImp()
+    {
+        std::cout << "base implementation of toggle()!" << std::endl;
+    }
+
+    bool getImp(void)
+    {
+        std::cout << "base implementation of get()!" << std::endl;
+        return true;
+    }
 };
 
+//
+//  implementations
+//
+
+struct STM32_Pin : PinBase<STM32_Pin>
+{
+    STM32_Pin()
+    {
+        std::cout << "created STM32_Pin" << std::endl;
+    }
+
+    void setImp(bool logic)
+    {
+        std::cout << "stm32 pin set to " << logic << std::endl;
+    }
+
+    void toggleImp()
+    {
+        std::cout << "toggled stm32 pin" << std::endl;
+    }
+
+    bool getImp()
+    {
+        return true;
+    }
+
+
+    void STM32_stuff()
+    {
+        std::cout << "STM_32 specific stuff" << std::endl;
+    }
+};
+
+struct AVR_Pin : PinBase<AVR_Pin>
+{
+    AVR_Pin()
+    {
+        std::cout << "created AVR_Pin" << std::endl;
+    }
+
+    void setImp(bool logic)
+    {
+        std::cout << "AVR pin set to " << logic << std::endl;
+    }
+
+    void toggleImp()
+    {
+        std::cout << "toggled AVR pin" << std::endl;
+    }
+
+    bool getImp()
+    {
+        return true;
+    }
+
+    void avr_stuff()
+    {
+        std::cout << "AVR specific stuff" << std::endl;
+    }
+};
+
+template<typename T>
+void foo(T& base)
+{
+    base.set(true);
+    base.set(false);
+    base.toggle();
+}
 
 int main(void)
 {
-    std::cout << "CRTP example" <<std::endl;
+    STM32_Pin pin1;
+    AVR_Pin pin2;
+
+
+    pin1.STM32_stuff();
+
+    pin2.avr_stuff();
+
+    foo(pin1);
+    foo(pin2);
+
     return 0;
 }
\ No newline at end of file
diff --git a/CPP/CRTP/example/runtest b/CPP/CRTP/example/runtest
index f728227..12fab27 100755
Binary files a/CPP/CRTP/example/runtest and b/CPP/CRTP/example/runtest differ