Giedrius,

Thank you for schematics! It looks very similar to MircoChip's evolution board schematics.
Do you sell these boards somehow? I'd like to buy it if this is possible to save some time.

On your previous message you was talking about USB 1.1 issue. Yes, it is well-known issue and people use USB 2.0 HUB between AR9331 and USB1.1 devices. We did the same. But we experience some other issues. Our setup can work week or two without issues and after that USB can suddenly glitch. Or can still work ok. The main problem that we can't reproduce issue manually. We tried reduce power quality, generate some noise, etc. Nothing provides a way to glitch it. We can only wait running multiple boards at the same time and waiting if some of them will glitch.

Did you try sending large traffic over the USB UART and WiFi at the same time? Make a loopback UART by shortcircuiting it's TX and RX and run a script which writes and reads lots of data over the USB UART (CDC). Then connect two carambolas together and use a traffic generator (such as iperf) to generate WiFi traffic.

We completely redesigned our board. Now we use USB2640 hub and have much cleaner DC-DC converters. It worked for 1 week w/o glitches so far. Yesterday we installed it in industrial environment for a stress test.

If it will work w/o issues there for 2 weeks we will be very happy

kuzmuk, I'm interested to know if your current solution with the USB2640 hub works as expected?

Glad to know that it works in harsh(er) enviroments.
As for the Carambolas, if it makes you feel any better you're not the only one waiting A new batch should arrive soon, but I have a feeling that it won't last long.