o add first working draft of usb version

o having bad sync problems only can use 4 bytes buffer, supper slow

poc/avr_usbload/requests.h

@@ -16,18 +16,18 @@
 #ifndef __REQUESTS_H_INCLUDED__
 #define __REQUESTS_H_INCLUDED__
 
-#define CUSTOM_RQ_ECHO          0
+#define CUSTOM_RQ_UPLOAD        0
 /* Request that the device sends back wValue and wIndex. This is used with
  * random data to test the reliability of the communication.
  */
-#define CUSTOM_RQ_SET_STATUS    1
+#define CUSTOM_RQ_DOWNLOAD     1
 /* Set the LED status. Control-OUT.
  * The requested status is passed in the "wValue" field of the control
  * transfer. No OUT data is sent. Bit 0 of the low byte of wValue controls
  * the LED.
  */
 
-#define CUSTOM_RQ_GET_STATUS    2
+#define CUSTOM_RQ_CRC_CHECK    2
 /* Get the current LED status. Control-IN.
  * This control transfer involves a 1 byte data phase where the device sends
  * the current status to the host. The status is in bit 0 of the byte.