Hello,
We have a USB issue on the AM3703 at cold temperature and we would like to generate an eye diagram from the onboard USB host controller. I have a bare-metal memory test app that can be executed by u-boot. I have tried without success to program the controller in the USB test mode to generate the test_packet required for the USB eye diagram. I have the manual for the AM3703, and I can see the register set does support the test_mode, but I have not succeeded in getting it into test_mode.
As I understand it, the official USB compliance app from the USB-IF only runs on Windows, which doesn't help us with our embedded product. I have also looked at the linux testusb code but it does not do what we want. I don't believe our USB driver has support for this either, which would probably not be desired in a production driver anyway.
We are using kernel version is 2.6.39 armv7l
I was thinking even some pseudo code might help get me there . I'm guessing my problem is with the L3 or L4 interconnect, as what I have seen so far is that when I try to read or write to the USB Host register set, I get data aborts. My code has a data abort handler and that's where I end up.
For instance, I can access the General Purpose Timer 0 registers ok, and I can access the serial port ok, but for the USB host controller, I feel like I am not setting up some pre-requisite peripheral muxes or interconnects. I have also tried to access the registers with different widths,:bytes, hword, word, etc but always get data abort.
Thanks for your help.
JC