In this video you will learn how to transfer file to NuttX using the ZMODEM protocol in a separated serial port instead of using the serial console port.
These are the commands used on Linux to setup the USB/Serial port:
$ stty 115200 cs8 -parenb -crtscts -F /dev/ttyUSB1
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https://www.youtube.com/watch?v=xZIX0SjkSbk