#if CPU_CM3_SAM3X
#define TWI0_BASE 0x4008C000
#define TWI1_BASE 0x40090000
+#elif CPU_CM3_SAM3N || CPU_CM3_SAM3S
+ #define TWI0_BASE 0x40018000
+ #define TWI1_BASE 0x4001C000
+#elif CPU_CM3_SAM3U
+ #define TWI0_BASE 0x40084000
+ #define TWI1_BASE 0x40088000
#else
#error TWI registers not defined for selected CPU
#endif