I'm not 100% sure but I think Chirp will only work with a COM port.
And also there probably is some initial handshake the radio does with
Chirp to tell it to start sending data. I'm by far no expert at this so you might
want to read some other replies from the guys who actually do the Chirp program
modifications for new radios and add more features, bug fixes etc... They read
the list.
From:
Bob Nielsen <n7xy@clearwire.net>
To: Discussion of CHIRP <chirp_users@intrepid.danplanet.com>
Sent: Sunday, November 17, 2013 9:02 PM
Subject: [chirp_users] Uploading to Icom ID-31 uSD memory card