No serial ports on imac

[MikeA]

Hi,
I have an imac and teensy 4.1. and using the latest arduino s/w. Most times the Teensy port is not recognised and I cannot work out where the fault lies. Sometimes it works, most time its does not. I have tried unplugging cables, pressing the reset switch etc. It is unreliable and frustrating. I have tried different usb sockets both directly into the imac and on an anker expansion box. Again sometimes they work but not reliably. Arduino boards work flawlessly.

I have spent a lot of time programming with 3.5/6 upgrading to , and new stuff with 4.1, but I have to say I am thinking of giving up and looking for another board to use because I am fed up unplugging and plugging cables in, at this sitting for nearly half an hour and not being able to get on with what i want.

If anyone has any suggestions i would be most grateful.

 

[BriComp]

Have you tried a different cable? Sometimes Teensy 4.x's faster USB exhibits this sort of behaviour with cables that are not quite up to it. This would explain the sometimes it works and sometimes it doesn't.

 

[clinker8]

My Mac Book Pro M3 connects to Teensy 4.1 just fine. Some cables are charge only, they will not connect. Some cables seem to wear out, so I just replace them.

 

[PaulStoffregen]

Here's 3 guesses...

1: Teensy uses HID protocol by default, not Serial. If you only look for /dev/cumodem or other USB serial while it's in HID mode, you would conclude it isn't connected when in fact it is working properly with HID rather than Serial protocol.

2: Teensy 4.0 uses 480 Mbit speed, whereas most other boards are only 12 Mbit speed. Low quality cables, or very long cables, or too many adaptors can cause signal quality problems that impact high speed devices but slower speeds still are able to work.

3: USB-C is supposed to have 5K resistors on 2 pins to tell your Mac to supply power. If using adaptors without these resistors, your Mac might not be turning on power to the port. Easiest solution is to use a powered USB hub.