AT91SAM9RL64-EK USB "Device Not Recognized" running from ext SDRAM (using Keil toolset)

We are failing to get the USB to work on both our own module and the AT91SAM9RL64-EK when running from external SDRAM. The PC justs reports "Device Not Recognized". The software is responding to the incoming requests and the device descriptor is sent out when it is requested but it looks as though the PC is not getting it.

We are using the Atmel supplied USB CDC example running from ext SDRAM as well as our own modified code - neither of which will work. There are no problems with other USB devices enumerating on the PC.

Please can someone give us some help? Does anyone have source files (boot and USB in External SDRAM) that use the Keil compiler (or even any compiler!) that we can look at?

Many thanks

Mike

Mike, we are using Linux kernel 2.6.30, U-boot 1.3.4, AT91Bootstrap 1.14 and the Codesourcery GNU compiler toolchain (Linux i386 host to AT91Sam9 target). The CPU we use is the AT91SAM9G20 and we are having troubles with the USB Device Port also.

The test we run on the development board has run for over a day with no issue, but our board only runs for a few minutes before locking up. I assume our board layout is leading to more bad USB messages and the current Linux driver (patches for 2.6.30) does not respond properly to missed ACKs.

You might have to invest a lot of time to move to our environment... so I don't have a solution for you, but the Atmel USB device port does seem to work on the 9G20 (and earlier.)

Have you tried printing out the UDP_CSRx register contents, to see how the flags are responding to the communications with the host (PC)? That is what we have done to isolate our problem down to bad packets and bad timeout handling in the Linux driver.

JBond

Thanks JBond for your reply.

For some reason our USB device is now enumerating 25% of the time (after weeks of it not even getting past the device descriptor being sent!). It's very strange as this code has not been changed!! The wind must be blowing in a different direction or something!

It is still not reliable though as sometimes it does "device not recognized", sometimes it comes up with the yellow exclamation in Device Manager and other times it looks ok in Device Manager and can connect a Terminal session to it though haven't got my code implemented yet to anything with any received characters.

I will continue looking at this and post how it goes.

Thanks

Mike

Mike it really sounds like a hardware issue, namely a signal integrity issue. Try putting a cell phone (or any source of noise like a switching power supply might be better) next to it and see if the Device Not Recognized happens more often.

Have the engineer check out the gerber files (graphical files depicting the copper layout) for the layout of the DDP and DDM signals for the USB Device Port. If they run by clocks in the 10 MHz region or nearby the guts of a switching power supply then those could be it.

Another very likely issue is the power supply having too much noise from the switcher... but I could go on forever, the hardware guys should know what to look for.

All you can do is look at the packets in your driver received from the computer and see how clean they are. If you are using the UMDF on Windows to develop a USB device driver, then you can look at the packets on that side. It would be nice if Windows had a packet statistics view for USB devices. (I could not find it while trying to debug my wife's Motorola phone last night, sigh).

JBond

Hello Mike,
where did you get sample USB source code.Could you please reply so that it helps me working with at91sam9g45 board