Is there any license issue in distributing the source codes from ATMEL point of view?
Yes, you can distribute it:
"Copyright (C) 2010 Atmel Corporation. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. The name of ATMEL may not be used to endorse or promote products derived from this software without specific prior written permission.
4. ATMEL grants developer a non-exclusive, limited license to use the Software as a development platform solely in connection with an Atmel AVR product
You can find the license on the asf.atmel.no
© 2019 Microchip Technology Inc.