I tried adding the -P usb argument and got the same error message, except instead of "unknown" it calls it "usb." The avrdude tutorial said it will automatically look in the usb for the programmer so it wasn't necessary. I looked up the name of the usb, thinking I may have not used the correct name to call it and tried again, but I got the same error. Here's both attempts:
Roberts-MacBook-Pro:~ robertwinter$ avrdude -P usb -c arduino -p t45 -U flash:w:firefly.hex
avrdude: ser_open(): can't open device "usb": No such file or directory
ioctl("TIOCMGET"): Inappropriate ioctl for device
avrdude done. Thank you.
Roberts-MacBook-Pro:~ robertwinter$ ls -l /dev/cu.*
crw-rw-rw- 1 root wheel 33, 1 Aug 20 09:17 /dev/cu.Bluetooth-Modem
crw-rw-rw- 1 root wheel 33, 3 Aug 20 09:17 /dev/cu.Bluetooth-PDA-Sync
crw-rw-rw- 1 root wheel 33, 11 Aug 20 11:17 /dev/cu.usbmodemfa131 <--------------- I then tried using this instead
Roberts-MacBook-Pro:~ robertwinter$ avrdude -P usbmodemfa131 -c arduino -p t45 -U flash:w:firefly.hex
avrdude: ser_open(): can't open device "usbmodemfa131": No such file or directory
ioctl("TIOCMGET"): Inappropriate ioctl for device
avrdude done. Thank you.
Am I specifying the serial port correctly?
And I guess the biggest question I have is: Is there an easier way to do this? I feel like I'm over complicating things, and perhaps there is a better way to insert the source code (in C++ instead of hex?) into the Arduino environment so I can get this chip programmed? What would you do if you were me?