USB Issue Troubleshooting

[aolofsson]

Hi all,

There are quite a few posts related to USB port failures. The goal of this post is to summarize all of them and to set the record straight.

The issue:
The USB phy does not always get initialized properly coming out of reset on some boards. After successful initialization, the USB port works fine.

Statements:
*Since day one, we have tested the USB port on every board shipped
*We have shipped 10,000 Parallella boards to 7,000 customers to date and have only received issue reports from a small number of customers
*We have spent significant time debugging this problem (internal to Adapteva and external) and unfortunately we have not found an acceptable bullet proof workaround yet
*We will keep working on resolving this issue, but given our limited resources and other high priority items that need to be dealt with, we can't give a time line for when this will be resolved.

Some data:
* The probability of successful USB initialization varies between boards.
* Keeping USB device plugged in during powerup increases probability of success
* A power cycle reset is more likely to work than a push button reset
* Probability of success increased by using longer USB cables
* Probability of success increased by using certain USB peripherals/hub setups
* Most boards work with all combination of hubs/peripherals (no restrictions)

How to report a USB problem:
* Failure mode (sometimes or always?)
* Headless/hdmi configuration
* FPGA/Linux/Ubuntu version being used
* Fan used?
* SKU#
* For SKU A101040 boards owners, an indication whether the U13 device is populated
* Power supply used
* Recommended: A picture of your USB setup (as shown here)

Sincerely,
Andreas

[ajtravis]

[Morgaine]

[theover]

Hi,

In my case of the 7010 board without mounted U13 chip, usb regularly fails at startup, maybe 50 % chance, i don't know.

If I reset with the button, USB always works, but of course this can upset the OS.

I've made a de-bounced startup circuit with the supplied wall wart, which seems to increase the chance of a startup with USB.

I don't think HDMI or not made a difference, I used the latest Linux and FPGA of a couple of months ago.

I've used various USB units, a long extension cable improved startup chance (but not near 100%), and conrad switchable hub.

T.

[ajtravis]

[aolofsson]

Tony,

Thanks for the detailed feedback. I noticed in the picture that only one board had USB/HDMI connected. Under what conditions were the 10 tries done for board 1-4? Were all of them connected to USB dongles at power on? Your results fit reasonably well with our data if board 4 is the top one and you only had that USB cable connected. If this was not the case, then we are back to head scratching...

Andreas

[ajtravis]

[RomanLudwig]

[Sean S]

Hi Andreas

Can you please clarify "only received issue reports from a small number of customers"? Through what means are you referring to for receipt of issue reports and do you think this is a realistic reflection of the number of customers that are experiencing USB problems?

If you consider the number of view on the subject of "USB not working" which currently stands at "Views: 4882" then one of two things are possible

- either the same people have nothing better to do than view this thread over and over desperately hoping for a solution...
- or many people are having issues with USB.

You claim to have shipped 10 000 boards to 7 000 customers... Which would mean that roughly half of the people that have boards have viewed this thread - implying that they have issues with USB too. That in my head does not account for a "small number of customers".

It has been suggested that I RMA my board but being in the UK, I can't justify the cost of shipping at my expense. In addition as the board was a gift, I am being told that I cannot RMA the board but need to hassle someone else to go through the RMA process which I don't think it fair. So please don't make that suggestion to me.

I am happy to see that after all of noise, you have finally made a formal statement. However, this needs to be followed up with a full solution - as you said. And I think you need to offer people their money back as well as an option. Many people require USB to be stable.

Honestly, the Parallella concept is great. Just a pity that such a key feature has no resolution or understanding after such a long time.

Sean

[AndyC]

* Failure mode (sometimes or always?)

75% failure


* Headless/hdmi configuration

hdmi


* FPGA/Linux/Ubuntu version being used

Standard ones from http://www.parallella.org/create-sdcard/


* Fan used?

5V60mm - avg temp 55


* SKU#

P1602-DK02


* Power supply used

4A 5V switched