3 files changed, 16 insertions, 3 deletions
diff --git a/cores/arduino/CDC.cpp b/cores/arduino/CDC.cpp
index 63983d9..7c7eacf 100644
--- a/cores/arduino/CDC.cpp
+++ b/cores/arduino/CDC.cpp
@@ -49,8 +49,8 @@ const CDCDescriptor _cdcInterface =
 
 	//	CDC data interface
 	D_INTERFACE(CDC_DATA_INTERFACE,2,CDC_DATA_INTERFACE_CLASS,0,0),
-	D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT),USB_ENDPOINT_TYPE_BULK,0x40,0),
-	D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN ),USB_ENDPOINT_TYPE_BULK,0x40,0)
+	D_ENDPOINT(USB_ENDPOINT_OUT(CDC_ENDPOINT_OUT),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0),
+	D_ENDPOINT(USB_ENDPOINT_IN (CDC_ENDPOINT_IN ),USB_ENDPOINT_TYPE_BULK,USB_EP_SIZE,0)
 };
 
 int CDC_GetInterface(u8* interfaceNum)
diff --git a/cores/arduino/USBAPI.h b/cores/arduino/USBAPI.h
index 4abd961..5caacc5 100644
--- a/cores/arduino/USBAPI.h
+++ b/cores/arduino/USBAPI.h
@@ -32,6 +32,12 @@ typedef unsigned long u32;
 
 #include "Arduino.h"
 
+// This definitions is usefull if you want to reduce the EP_SIZE to 16
+// at the moment only 64 and 16 as EP_SIZE for all EPs are supported except the control endpoint
+#ifndef USB_EP_SIZE
+#define USB_EP_SIZE 64
+#endif
+
 #if defined(USBCON)
 
 #include "USBDesc.h"
diff --git a/cores/arduino/USBCore.cpp b/cores/arduino/USBCore.cpp
index 05e2f24..fd25793 100644
--- a/cores/arduino/USBCore.cpp
+++ b/cores/arduino/USBCore.cpp
@@ -253,7 +253,7 @@ u8 USB_SendSpace(u8 ep)
 	LockEP lock(ep);
 	if (!ReadWriteAllowed())
 		return 0;
-	return 64 - FifoByteCount();
+	return USB_EP_SIZE - FifoByteCount();
 }
 
 //	Blocking Send of data to an endpoint
@@ -326,6 +326,7 @@ u8 _initEndpoints[] =
 
 #define EP_SINGLE_64 0x32	// EP0
 #define EP_DOUBLE_64 0x36	// Other endpoints
+#define EP_SINGLE_16 0x12
 
 static
 void InitEP(u8 index, u8 type, u8 size)
@@ -344,7 +345,13 @@ void InitEndpoints()
 		UENUM = i;
 		UECONX = (1<<EPEN);
 		UECFG0X = _initEndpoints[i];
+#if USB_EP_SIZE == 16
+		UECFG1X = EP_SINGLE_16;
+#elif USB_EP_SIZE == 64
 		UECFG1X = EP_DOUBLE_64;
+#else
+#error Unsupported value for USB_EP_SIZE
+#endif
 	}
 	UERST = 0x7E;	// And reset them
 	UERST = 0;