Added basic Serial-over-USB functionality

- Added "streams" includes to the Makefile in order to be able to use chprintf().
- Added subsystems/serial/chibiesc_usb.h/.c, configuring an USB CDC device and sending "Test\n" in a loop for testing
- Including the new usb files and calling usb_init() in main.c

Makefile

@@ -114,7 +114,10 @@ CSRC = $(STARTUPSRC) \
        $(PLATFORMSRC) \
        $(BOARDSRC) \
        $(TESTSRC) \
-       main.c
+       $(CHIBIOS)/os/hal/lib/streams/memstreams.c \
+       $(CHIBIOS)/os/hal/lib/streams/chprintf.c \
+       main.c \
+       subsystems/serial/chibiesc_usb.c
 
 # C++ sources that can be compiled in ARM or THUMB mode depending on the global
 # setting.
@@ -145,6 +148,7 @@ ASMSRC = $(STARTUPASM) $(PORTASM) $(OSALASM)
 
 INCDIR = $(STARTUPINC) $(KERNINC) $(PORTINC) $(OSALINC) \
          $(HALINC) $(PLATFORMINC) $(BOARDINC) $(TESTINC) \
+         $(CHIBIOS)/os/hal/lib/streams \
          $(CHIBIOS)/os/various
 
 #

main.c

@@ -17,6 +17,8 @@
 #include "ch.h"
 #include "hal.h"
 #include "test.h"
+#include "chprintf.h"
+#include "subsystems/serial/chibiesc_usb.h"
 
 /*
  * This is a periodic thread that does absolutely nothing except flashing
@@ -49,7 +51,7 @@ int main(void) {
    */
   halInit();
   chSysInit();
-  osalSysEnable(); // just copied here from example to test why LED blinking doesn't work
+  //osalSysEnable(); // just copied here from example to test why LED blinking doesn't work
 
   /*
    * Activates the serial driver 2 using the driver default configuration.
@@ -64,6 +66,7 @@ int main(void) {
    */
   //chThdCreateStatic(waThread1, sizeof(waThread1), NORMALPRIO, Thread1, NULL);
 
+  usb_init(); // Serial over USB initialization
   /*
    * Normal main() thread activity, in this demo it does nothing except
    * sleeping in a loop and check the button state.