extern unsigned char return_on_error;
 extern unsigned char error_occured;
 
-void SendCommand(UsbCommand *c);
-bool ReceiveCommandPoll(UsbCommand *c);
-void ReceiveCommand(UsbCommand *c);
+void SendCommand_(HidCommand *c);
+bool ReceiveCommandPoll(HidCommand *c);
+void ReceiveCommand(HidCommand *c);
 struct usb_dev_handle* FindProxmark(int verbose, unsigned int *iface);
 struct usb_dev_handle* OpenProxmark(int verbose);
 void CloseProxmark(void);
 
+struct prox_unit {
+  usb_dev_handle *handle;
+  char serial_number[256];
+};
+
 #endif