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TPS2546: USB device not functional after resume from S3

Antony Lin
Genius 13480 points
Part Number: TPS2546

Hi,

Currently TPS2546 is configured as below.

  • System S0 mode: CTL1/CTL2/CTL3/ILIM_SEL = 1101 (SDP)
  • System S3 mode: CTL1/CTL2/CTL3/ILIM_SEL = 0101 (SDP)

The system can be waken up from me from S3 mode to S0 mode by USB mouse, but some of the USB mouses becomes not workable after system resume to S0, and it can be recovered by re-plugin the USB mouse.  Meanwhile, I see VBUS drop and back to 5V during resume, is it normal.  Please check below for 2 failed mouses and two passed mouses.  Please share your inputs.  THanks!

Antony

  • 0
    TI__Genius 9630 points

    Hi Antony,

    Two things about your test:

    1. The first thing is that you are not using the right CTL pin inputs. The only CTL pin inputs that are recommended to be used for Wake on USB are:

    1. 111 (CDP/SDP2) to 011 (DCP-Auto)

    2. 010 (SDP1) to 011 (DCP-Auto)

     

    2. I believe you are experiencing another issue as well. I tested your issue in the lab using the TPS2546EVM and discovered I was running into the same problem, my mouse was not able to wake up the system. The issue only arose when my computer was not plugged in. I am not sure how you are testing, but if your test set up is similar to mine, then the problem is in the computer's sleep features, not with the TPS2546 itself. Here is how I performed my test: 

    - Plugged the TPS2546EVM into a computer and plugged a wireless mouse (tested also with wired keyboard) into the TPS2546EVM. 

    - I tested this in both supported wake states: 111 and 010

    - Put the computer to sleep

    - Used the mouse or keyboard to wake the computer

    I was only able to wake the computer if my computer was plugged into power. My results of the passing tests are shown below. As you noted, VBUS does not ever discharge when the computer is put to sleep and then consequently woken up. The wake up is attempted at the trigger point on the scope capture. 

    111 S0 state:

    010 S0 State:

    My scope captures looked very similar to yours when the computer was not plugged in to power. VBUS would discharge when the mouse was moved to attempt to wake up the computer and the computer would not wake. 

    If this is your issue as well, then your solution will be found in changing your computer's wake settings. 

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    TI__Genius 13480 points

    Hi Emma,

    Thanks for your comments.  Some further questions,

    • Currently the customer issue is "mouse not workable after resume from S3" instead of "System can't wake up from S3 mode through USB mouse."  Since their S0/S3 configuration does not match the only two configurations specified for "Wake-on-USB", do you mean their wake-up behavior is not right which cause the issue of "mouse not workable after resume from S3"?
    • Normally we do not expect a VBUS drop during wake-on USB, right?  Do you think they have a VBUS drop during resume due to incorrect configurations or not charging adapter connected to their NB?

    Antony

  • 0 in reply to Antony Lin
    TI__Genius 9630 points

    Hi Antony,

    • I think that the reason the mouse is not working after resume from S3 is because VBUS is discharging. I am not sure whether the customer system has VBUS discharge due to their incorrect configuration or due to their computer's power settings. The issue I saw while on battery power was that my computer would go to sleep, and the mouse or keyboard would stay connected. As soon as I would shake the mouse or tap on the keyboard, VBUS would discharge. 
    • VBUS should not drop during wake-up on USB. They would have to test on their system.

    Thanks,

    Emma

  • 0 in reply to Emma Hoying
    TI__Genius 9630 points

    Hi Antony,

    After doing some more testing, I found that in the 111 configuration, that VBUS would discharge and the system would never wake up on battery power (shown below) which is different from the issue your customer is seeing. 

    So because you are seeing a slightly different issue, please try changing the CTL pins. The system will override the pin change from 111 to 011 and will also override the pin change from 010 to 011. 

    Thanks,

    Emma