Mega 2560 sometimes cannot connect to Mac using USB hub


I’m encountering a strange problem on Mac OS Sierra.

First I bought Arduino Mega 2560 and installed FTDI driver. All worked fine each time I connect it to Mac via USB Hub.

Then I also bought Arduino Uno and installed CH340 drivers.
Now Mega 2560 sometimes works, sometimes not. This morning I plugged it in, it worked for around 2 hours and then Arduino suddenly stopped. If I unplugged and plug in again, it does now show desired port in list of ports in Arduino IDE. Restarting Mac sometimes helps, sometimes not. I also get the same behavior with Arduino Uno. Sometimes port cant be seen in Arduino IDE, so I cant connect and sometimes it works without any problem.

It is important to note that I’m using Mac 2017, without a USB port, so I’m using USB HUB to connect Arduino via USB cable. Can it maybe cause issues? Of maybe some other program is using same PORT? Or maybe these 2 drivers (FTDI and CH340) are somehow interfering in some moments?

I mean, it is totally inconsistent, sometimes it works, sometimes it simply disappears. Sometimes first restart of Mac helps, sometimes I need to restart 2-3 times to make it work.

Thanks you very much in advance,


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You could try them on a PC, but as neither of you products are Arduino branded boards, I don't have any more experience to go by.

I would change your USB lead, I had one like that once.

Any chance of short circuiting on metal surface, by components you wired to your arduinos etc? I don't have a mac. If you plug in a usb device or unplug, does it play an audible chime like PC does? If it does that unexpectedly and you're not short circuiting your arduino, neither do you have stuff wired up on arduino, then either ports or cables are going bad.

Thanks for answers everyone.

Yes, I hear a sound when I plug usb device to mac. This morning for example all worked fine when I first plug it in. After half of an hour of work, Mega 2560 just turned off (red diodes turned off). After plug off/plug in again, I hear a sound on Mac, red diodes are on again but I cannot see or select a port dev/cu.usbserial-A50285Bl, which I normally chose when mega is connected.

Usually it worked much better on PC with Arduino Uno (which also has same issue on Mac as Mega, as stated in original post). But the thing is I never tried mega on PC, since there is no driver for FTDI installed and yesterday didn't work for some reason. Will try it today hopefully.

Does anything get hot on the Mega?
What sort of current are you drawing?
You could be tripping the excess current circuit in the Mac and disconnected the USB.

My Mac doesn’t make a noise when a USB lead is connected. Maybe it is an option I turned off years ago and have forgotten about it.

If you load a blink sketch and remove anything attached to your arduino, will it stop working after some time?

Sorry for leaving you to wait. I got a new HUB for mac and now it works seamlessly. So no issue with circuit. Thank you for your help.

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