We are working on a tracker project, in that we have to design a common USB connection for ATSAML21J18B and a GSM module, where the functions of USB will be
1. GSM module should be able to firmware upgrade via USB.
2. Flashing the Micro-controller ATSAML21J18B.
3. The ATSAML21J18B will communicate to GSM module via same USB lines.
I have designed an idea for this but not sure whether correct or not, Please if someone can help me resolve this.