On Sierra (iMac) my Arduino IDE does not show up a usb port for the TinyDuino. For my Arduino Uno the USB port is ok.
On Yosemite (MacBook Pro 13) the Arduino IDE shows up the usb port and everything works fine.
What is the trouble with Sierra?
Is this a known issue?
How can I fix this?

Hello nobsy,

I have successfully been able to program a TinyDuino on MacOS Sierra for a couple of different projects, so I'm not sure what issue you may be encountering as the Port seems to show up for the Yosemite OS and not Sierra.

I'll first advise you to ensure the power switch on is toggled to 'on.'

If that's not the issue, you may want to check out the latter part of this tutorial to first see if your laptop is even recognizing the USB port: https://tinycircuits.com/blogs/learn/port-trouble-windows-and-mac-help

This will quickly show you how to identify whether your Mac is identifying the TinyDuino connected via USB or not, removing the Arduino IDE from the equation.

If you're still having issues, we will look further into this, so please let me know!

-Laveréna