diff --git a/Arduino/CanGrow/CanGrow.ino b/Arduino/CanGrow/CanGrow.ino
index 56dd492..a737ebe 100644
--- a/Arduino/CanGrow/CanGrow.ino
+++ b/Arduino/CanGrow/CanGrow.ino
@@ -68,23 +68,17 @@
 
 
 
-/*
- *  CanGrow platform specific includes
- */
-
-#ifdef ESP8266
-#include "include/CanGrow_ESP8266.h"
-#endif
-
-#ifdef ESP32
-#include "include/CanGrow_ESP32.h"
-#endif
 
 /*
  *  CanGrow includes
  */
 
+/* main header file, where all variables, consts and structs get defined */
 #include "include/CanGrow.h"
+/* CanGrow platform specific includes */
+#include "include/CanGrow_ESP8266.h"
+#include "include/CanGrow_ESP32.h"
+/* CanGrow header with all functions */
 #include "include/CanGrow_Core.h"
 #include "include/CanGrow_Wifi.h"
 #include "include/CanGrow_LittleFS.h"
diff --git a/Arduino/CanGrow/include/CanGrow.h b/Arduino/CanGrow/include/CanGrow.h
index 93186e7..87d313f 100644
--- a/Arduino/CanGrow/include/CanGrow.h
+++ b/Arduino/CanGrow/include/CanGrow.h
@@ -96,14 +96,29 @@ struct Config_Grow {
 Config_Grow configGrow;
 
 
-
-
-
-
-
-
 struct Config {
   char test[16] = "123";
 };
 
 Config config;
+
+/* actual structure initialization for Pin_Index is done within the header files
+ * for ESP32 and ESP8266
+ * 
+ * notes explenation:
+ *   - BF_L: BootFails when LOW
+ *   - BF_H: BootFails when HIGH
+ *   - FM_L: FlashMode needs LOW to enter
+ *   - IN_O: Input Only
+ */
+const char* BF_L = "BF_L";
+const char* BF_H = "BF_H";
+const char* FM_L = "FM_L";
+const char* IN_O = "IN_O";
+
+struct Pin_Index {
+  const byte gpio;
+  const char* notes[8];
+  char* usedBy[8];
+};
+
diff --git a/Arduino/CanGrow/include/CanGrow_ESP32.h b/Arduino/CanGrow/include/CanGrow_ESP32.h
index 2bbdc7c..4e3ea05 100644
--- a/Arduino/CanGrow/include/CanGrow_ESP32.h
+++ b/Arduino/CanGrow/include/CanGrow_ESP32.h
@@ -26,11 +26,62 @@
  * THE SOFTWARE.
  *
  */
-
+#ifdef ESP32
 
 #define PinWIPE 2
 #define PinWIPE_default LOW
 #define Pin_I2C_SCL = 22;
 #define Pin_I2C_SDA = 21;
 
-// free usable pins
+/* https://randomnerdtutorials.com/esp32-pinout-reference-gpios/
+ * 
+ * free usable pins
+ * - GPIO 0     PU    OK    outputs PWM signal at boot, must be LOW to enter flashing mode
+ * - GPIO 4     OK    OK    
+ * - GPIO 5     OK    OK    outputs PWM signal at boot, strapping pin
+ * - GPIO 12    OK    OK    boot fails if pulled high, strapping pin
+ * - GPIO 13    OK    OK    
+ * - GPIO 14    OK    OK    outputs PWM signal at boot
+ * - GPIO 15    OK    OK    outputs PWM signal at boot, strapping pin
+ * - GPIO 16    OK    OK    
+ * - GPIO 17    OK    OK    
+ * - GPIO 18    OK    OK    
+ * - GPIO 19    OK    OK    
+ * - GPIO 23    OK    OK    
+ * - GPIO 25    OK    OK    
+ * - GPIO 26    OK    OK    
+ * - GPIO 27    OK    OK    
+ * - GPIO 32    OK    OK    
+ * - GPIO 33    OK    OK    
+ * - GPIO 34    OK    input only
+ * - GPIO 35    OK    input only
+ * - GPIO 36    OK    input only
+ * - GPIO 39    OK    input only
+ */
+
+
+// 
+const byte pinIndex_length = 21;
+// initialize pinIndex with all usable GPIOs
+Pin_Index pinIndex[] = {  { 0, FM_L },
+                          { 4 },
+                          { 5 },
+                          { 12, BF_H },
+                          { 13 },
+                          { 14 },
+                          { 15 },
+                          { 16 },
+                          { 17 },
+                          { 18 },
+                          { 19 },
+                          { 23 },
+                          { 25 },
+                          { 26 },
+                          { 27 },
+                          { 32 },
+                          { 33 },
+                          { 34, IN_O },
+                          { 35, IN_O },
+                          { 36, IN_O },
+                          { 39, IN_O }  };
+#endif
diff --git a/Arduino/CanGrow/include/CanGrow_ESP8266.h b/Arduino/CanGrow/include/CanGrow_ESP8266.h
index 1595039..0921818 100644
--- a/Arduino/CanGrow/include/CanGrow_ESP8266.h
+++ b/Arduino/CanGrow/include/CanGrow_ESP8266.h
@@ -26,14 +26,16 @@
  * THE SOFTWARE.
  *
  */
+#ifdef ESP8266
 
-
+// GPIO 2 Boot fails if pulled to LOW
 #define PinWIPE 2
 #define PinWIPE_default HIGH
 #define Pin_I2C_SCL = 5;
 #define Pin_I2C_SDA = 4;
 
-/*
+/* https://randomnerdtutorials.com/esp8266-pinout-reference-gpios/
+ * 
  * free usable pins
  * - GPIO 0 / D3 boot fails if pulled LOW
  * - GPIO 12 / D6
@@ -42,3 +44,14 @@
  * - GPIO 15 / D8 Boot fails if pulled HIGH
  * - GPIO 16 / D0
  */
+
+const byte pinIndex_length = 6;
+// initialize pinIndex with all usable GPIOs
+Pin_Index pinIndex[] = {  { 0, BF_L },
+                          { 12 },
+                          { 13 },
+                          { 14 },
+                          { 15, BF_H },
+                          { 16 }  };
+
+#endif
diff --git a/Arduino/CanGrow/include/CanGrow_Webserver.h b/Arduino/CanGrow/include/CanGrow_Webserver.h
index 771df33..7cf1840 100644
--- a/Arduino/CanGrow/include/CanGrow_Webserver.h
+++ b/Arduino/CanGrow/include/CanGrow_Webserver.h
@@ -47,7 +47,7 @@
 
 
 AsyncWebServer webserver(80);
-// log incoming requests
+// load requestLogger middleware
 LoggingMiddleware requestLogger;