Not passing loop-back test on Mac OS X 10.5.8

Hi all,

i started with classic programmer not responding problems, then i found loop back test -- and it's not passing, then i tried programming the arduino from couple of another computers and both of them went ok (Ubuntu and Mac OS X 10.6.x)

SO it's my particular Mac OS X 10.5.8 system - something is wrong with CDC driver - the arduino gets recognized, /dev/tty.usbmodemXX is being created, but when i write to it, it's not working - no TX RX leds flashing, no loopback, nothing.

SO i'm asking all the other mac users in this forum for a HELP - how do i debug CDC on my system? where do i start? to what forums do i write? what keywords do i put to google?

this might be of help to lots of frustrated mac users posting to this forum, cursing arduino

i'm a fulltime programmer and can handle complicated stuff.. please post all your insights

Hi all,

after several days of frustration and my previous email of despair i poked around in my system:

after connecting the arduino i ran sudo kextstat | grep CDC to display loaded kernel extensions relative to CDC:

  141    0 0x2e7f1000 0x3000     0x2000     com.apple.driver.AppleUSBCDC (3.2.13) <46 12>
  142    0 0x344f4000 0x3000     0x2000     com.ZTE.driver.ZTEUSBCDCACMControl (1.2.1) <46 12>
  144    0 0x4bb61000 0x6000     0x5000     com.apple.driver.AppleUSBCDCACMData (3.2.13) <105 46 12 6 5 4>

that ZTE driver looked suspicious for me and i deleted it from /System/Library/Extensions

then kexstat displayed:

  147    0 0x2e7f1000 0x3000     0x2000     com.apple.driver.AppleUSBCDC (3.2.13) <46 12>
  148    0 0x344dc000 0x3000     0x2000     com.apple.driver.AppleUSBCDCACMControl (3.2.13) <46 12>
  149    0 0x4aad5000 0x6000     0x5000     com.apple.driver.AppleUSBCDCACMData (3.2.13) <105 46 12 6 5 4>

note AppleUSBCDCACMControl instead of ZTEUSBCDCACMControl and arduino now works!

So, if you can't pass loop back test on Mac OS X, try looking for some foreign CDC drivers poisoning the well.

Thank you for the follow-up.

Thank you SO MUCH for this aproach!!! I finally made my Arduino UNO work on a Macbook with OSX 10.5.8 after being lost days in the forums and in google and having find nothing. I did exactly what you did and ... voila!

My Best Regards and Long Live wishes!

Hi, i don't know what i have done however, i was mucking around with a couple of different arduinos Uno, leonardo etc, i had two on the go swapping out bits as i got them sorted on one etc...

anyway, I made a mod to a bit of code, and this would not upload, it had the error
ioctl("TIOCMGET"): Inappropriate ioctl for device
as best as I can tell this is a serial port failure of some kind?

I tried a different arduino, same result.

I tried a "new" sketch and still no connect...

I tried the loopback test on both the leonardo and the uno. both failed with a warning
could not open device, device not figured etc.

finally before closing "screen", screen advises me that it could not find a PTY

So anyone know what is up and how to fix it?

Kindest regards.

Graham.