View Full Version : Solved Strange USB problem

10-17-2011, 12:15 AM
Here's the setup: iMac uses Parallels to run Windows XP for Prop mainly tasks. I'd not used it for some time, a week or more, and today Prop cannot be found.

If I disable the FDTI my QuickStart board (QS) is powered; if I enable it it is unpowered!!! Very strange; I'd never seen this before.

With the iMac turned off (actually standby power) the QS LEDs glow slightly. When iMac turned back ON, all the LEDs light up until the Prop inits; this makes sense as the Prop i/Os are inputs. Then the Prop program runs and all LEDs are OFF. That is OK.

Now when I go into Windows and Prop IDE, when I enable the USB for FDTI use the LEDs dim again. Why would power be turned OFF when FDTI enabled?

I was about to upload a program to RAM when I found this effect. Baffling.

frank freedman
10-17-2011, 06:43 AM

My first thought was a short, but I remembered that depending on what is in the eeprom that takes off and runs in the prop, it will say that it can not find the prop even though "I" know it is running something fairly intense on timing and thus prevents the usb from seeing the prop long enough for the PC ware to think there is no prop out there. Not sure, but there is also on the forum, someone has noted that there could be problems with the usb serial causing resets depenging on external connections. Can't remember the thread title, but with in sept possibly.


10-17-2011, 07:22 PM
I re-started the iMac (that is turned power off, then back on after a long pause), then restarted Parallels and Windows and now it seems OK. Even printing had been stopped (printer off line or not ready error message). Not sure what that 'funny' was; not sure I've run into it before.

"Sorry, Folks. Move along, nothing happening here of interest" he said.