adds matrix i2c swap

drivers/arm/twi2c.h

@@ -15,4 +15,14 @@
  */
 
 #include "ch.h"
-#include "hal.h"
+#include "hal.h"
+
+#define slaveI2Caddress  0x30       /* Address in our terms - halved by later code */
+//#define myOtherI2Caddress 0x19
+
+I2CSlaveMsgCB twi2c_slave_message_process, catchError, clearAfterSend;
+
+void twi2c_slave_init(void);
+
+void twi2c_master_init(void);
+msg_t twi2c_master_send(i2caddr_t address, const uint8_t * txbuf, uint8_t * rxbuf, systime_t timeout);