TUSB2077A: HUB_CFG doesn't stay high

Hi Charles:

    Did TUSB2077A and downstream port device get detected by SOC ?

      HUB_CFG can be low if hub get into suspend mode, it didn't mean hub has issue.

Best

Brian

No, when I plug in a down stream device (i.e. a Mouse), hub_cfg flashes high briefly (2x) as it tries to enumerate (optical mouse lights up briefly) but I never see the device in the OS.

So just to confirm what you are saying, it is normal behavior for hub_cfg to be low when there are no devices downstream?

From schematic:

 1; need 15K pulldown for downstream port DP/DM.

 2: need to supply Vbus for downstream port device.

 3: how is reset signal pulse vs VDD supply?

Best

Brian

I have the 15k and supply Vbus on my connectors schematic sheet, so they are there.  The RST controller chip, U2, holds the RST line low until 3V3 is good.  I will scope onto that tomorrow and relay timing information on this thread.

I will try on our EVM to see what happens.

Best

brian

with my design, I am measuring 3V3 going high and 13ms later, RST goes high and stays high.  The behavior is the exact same when I have a device plugged in downstream at startup or if I do it well after the hub has been powered for a while.  I have also toggled RST after this time and it always goes back to the failed downstream enumeration with hub_cfg never staying high.  Do you by chance have any EVMs available that I could get to aid in my debug?

This very old device, we just has few for internal testing.

Best

Brian

CFG always high once a downstream port device is connected, it did jsut goes high for a sec if no device connected.

Best

 Brian