TUSB8020B-Q1: unable to enumerate devices with usb 2.0 when the divice is inserted into dowmstream of tusb8020

Hi,

On the downstream port scope waveform, if channel 1 is D+ and stays low, and channel 2 is D- are being driven high by the device, then the device indicates itself to be a low-speed device, not a full-speed or high-speed device.

Thanks

David

Hi,

thanks for your reply.

upstream can't detect any change on the D+/D- when any low-speed device,full-speed device and high-speed device were inserted into downstream port

Hi,

For the devices that were inserted into the downstream ports, are they self-powered or bus-powered device?

Can you take a scope picture of the DN1_VBUS, DP and DM? 

Thanks

David

Hi,

the devices is bus powerd

DN1_VBUS is 5V,have no scope picture

DP and DM scope pitcure is like this

Hi,

Does the TUSB8020B show up as a USB2.0 device also?

Thanks

David

Hi,

yes

lsusb show both USB3.0 device and USB2.0 device of TUSB8020

I think that upstream signals have no change when downstream have some devices inserted,so that host can't enumerate the devices

Hi,

When a hub detects a change on a port or when the hub changes its own state, it uses the Status Change endpoint to transfers data to the host.

Have you tried to plug a self-power device into the hub downstream port? I am trying to see if the issue is power related. 

In the scope waveform you attached, is channel 1 DP and channel 2 DM?

Thanks

David

HI,

In the scope waveform attached,channel 1 is DP and channel 2 is DM

I'll try self-power device later

Hi,

With Channel 1 being DP and stays low, and channel 2 being DM and goes high, the downstream device is indicating itself to be a low speed device, is this expected?

Thanks

David

Hi,

yes,the device is mouse

Can you send schematic for review?

Regards

Brian

Hi,

Are you seeing DM ever go low? What should happen is that the DM goes high, and stays high for ~100 ms and then a USB reset is sent from the host. In this case, the host is the USB3220C.

Thanks

David