diff --git a/Chapter09/type_safety/app/src/main_strong_types.cpp b/Chapter09/type_safety/app/src/main_strong_types.cpp
new file mode 100644
index 0000000..1031aaa
--- /dev/null
+++ b/Chapter09/type_safety/app/src/main_strong_types.cpp
@@ -0,0 +1,103 @@
+#include <cstdint>
+#include <cstdio>
+
+#include <stm32f072xb.h>
+
+#include <hal.hpp>
+#include <uart_stm32.hpp>
+
+#include <retarget.hpp>
+#include <cstring>
+
+#include <type_traits>
+
+namespace {
+
+constexpr uint8_t c_PUBLIC_ADDR = 0x01;
+constexpr uint16_t c_SUPERV_TIMEOUT = 0x0C80;
+
+class time {
+private:
+	uint16_t time_in_ms_;
+public:
+	explicit time(uint16_t time_in_ms) : time_in_ms_(time_in_ms){}
+	uint16_t & get_ms() {return time_in_ms_;}
+};
+
+time operator""_ms(unsigned long long t) {
+    return time(t);
+}
+
+class conn_l {
+private:
+	uint16_t val_; 
+public:
+	explicit conn_l(time t) : val_(t.get_ms()/0.625f){}
+	uint16_t & get() {return val_;}
+};
+
+class conn_p {
+private:
+	uint16_t val_; 
+public:
+	explicit conn_p(time t) : val_(t.get_ms()/1.25f){}
+	uint16_t & get() {return val_;}
+};
+
+
+using tBleStatus = bool;
+
+tBleStatus aci_gap_create_connection_wrapper( 
+                            conn_l LE_Scan_Interval, 
+                            conn_l LE_Scan_Window, 
+                            uint8_t Peer_Address_Type, 
+                            uint8_t Peer_Address[6], 
+                            conn_p Conn_Interval_Min, 
+                            conn_p Conn_Interval_Max, 
+                            time Conn_Latency, 
+                            time Supervision_Timeout, 
+                            conn_l Minimum_CE_Length, 
+                            conn_l Maximum_CE_Length) {
+                                static_cast<void>(LE_Scan_Interval);
+                                static_cast<void>(LE_Scan_Window);
+                                static_cast<void>(Peer_Address_Type);
+                                static_cast<void>(Peer_Address);
+                                static_cast<void>(Conn_Interval_Min);
+                                static_cast<void>(Conn_Interval_Max);
+                                static_cast<void>(Conn_Latency);
+                                static_cast<void>(Supervision_Timeout);
+                                static_cast<void>(Minimum_CE_Length);
+                                static_cast<void>(Maximum_CE_Length);
+
+                                return true;
+                            }
+};
+
+int main()
+{
+    hal::init();
+
+    hal::uart_stm32 uart(USART2);
+    uart.init();
+
+    retarget::set_stdio_uart(&uart);
+
+    const tBleStatus stat = aci_gap_create_connection_wrapper(
+            conn_l(80_ms),
+            conn_l(120_ms),
+            c_PUBLIC_ADDR,
+            nullptr,
+            conn_p(50_ms),
+            conn_p(60_ms),
+            0_ms,
+            4000_ms,
+            conn_l(10_ms),
+            conn_l(15_ms)
+    );
+
+    static_cast<void>(stat);
+    
+    while(true)
+    {
+    }
+}