Merge pull request arduino#132 from kaysievers/master

USBCore: Read the SAMD51 serial number

Author: ladyada

cores/arduino/USB/USBCore.cpp

@@ -244,26 +244,25 @@ bool USBDeviceClass::sendDescriptor(USBSetup &setup)
 		}
 		else if (setup.wValueL == ISERIAL) {
 #ifdef PLUGGABLE_USB_ENABLED
-#if defined(__SAMD51__)
-			char name[ISERIAL_MAX_LEN];
-			PluggableUSB().getShortName(name);
-			return sendStringDescriptor((uint8_t*)name, setup.wLength);
-#else
+#ifdef __SAMD51__
+			#define SERIAL_NUMBER_WORD_0	*(volatile uint32_t*)(0x008061FC)
+			#define SERIAL_NUMBER_WORD_1	*(volatile uint32_t*)(0x00806010)
+			#define SERIAL_NUMBER_WORD_2	*(volatile uint32_t*)(0x00806014)
+			#define SERIAL_NUMBER_WORD_3	*(volatile uint32_t*)(0x00806018)
+#else // samd21
 			// from section 9.3.3 of the datasheet
 			#define SERIAL_NUMBER_WORD_0	*(volatile uint32_t*)(0x0080A00C)
 			#define SERIAL_NUMBER_WORD_1	*(volatile uint32_t*)(0x0080A040)
 			#define SERIAL_NUMBER_WORD_2	*(volatile uint32_t*)(0x0080A044)
 			#define SERIAL_NUMBER_WORD_3	*(volatile uint32_t*)(0x0080A048)
-
+#endif
 			char name[ISERIAL_MAX_LEN];
 			utox8(SERIAL_NUMBER_WORD_0, &name[0]);
 			utox8(SERIAL_NUMBER_WORD_1, &name[8]);
 			utox8(SERIAL_NUMBER_WORD_2, &name[16]);
 			utox8(SERIAL_NUMBER_WORD_3, &name[24]);
-
-			PluggableUSB().getShortName(&name[32]);
+			name[32] = '\0';
 			return sendStringDescriptor((uint8_t*)name, setup.wLength);
-#endif
 #endif
 		}
 		else {