Testing loopback from ttyACM0 <-> ttyACM1.

example-usb-serial/cdc.h

@@ -2,8 +2,10 @@
 
 struct cdc;
 
+void cdc_init (void);
+void cdc_wait_configured (void);
+
 struct cdc *cdc_open (uint8_t num);
-void cdc_wait_configured (struct cdc *);
 void cdc_wait_connection (struct cdc *);
 int cdc_send (struct cdc *s, const char *buf, int count);
 int cdc_recv (struct cdc *s, char *buf, uint32_t *timeout);