TUSB8043: USB 2.0 enumeration issue

Hi Rohith,

In a typical application, USB 3.0 and USB 2.0 are enabled simultaneously.  The USB 3.0 and USB 2.0 sides of the hub operate independently of each other with the exception of port power control.  Can you confirm that power is enabled on the port when USB 3.0 is disabled?

Regards,

JMMN

Hi JMMN,

we have not used any power control functionality in the HUB, we have left the PWRCTLz and the OVERCURz pins in their default state.
and the state of the other pins are:
39 -SMBUSz/SS_SUSPEND - PU
40 -FULLPWRMGMTz /FULLAUTOz /SMBA1/SS_UP- PD
41 -PWRCTL_POL- PU
42 -GANGED/SMBA2/HS_UP - PD
45 -AUTOENz/HS_SUSPEND - PU
the power is enabled in the HUB and the devices all the time.

Regards,
R.Rohith yadav

Can you provide a schematic?

Hi ,

pls find the chematics for the USB_HUB section.

in this section we have used a USB-C connector and for that we have used a USB MUX for which the select lines have been given from our MCU.

PI3USB302-AZBEX- USB MUX

105450-0101 - USB-C connector

MUX working:

MUX_SEL=0 - TX1+/- and RX1 +/- is selected

MUX_SEL=1 - TX2+/- and RX2 +/- is selected

1. by default the MUX_SEL value is 0 so TX1+/- and RX1 +/- is of USB mux is connected to the USB HUB

2. when the USB-C cable is connected in the direction when the data comes from  TX1+/- and RX1 +/- the device enumarates as USB3.0 and works propely

3. when the USB-C cable is connected in the direction when the data comes from  TX2+/- and RX2+/- then the device enumrates as USB2.0, then we switch the MUX_SEL to 1 and reset the USB_HUB. now the HUB and the devices enumerate as USB 3.0 device

so the difficulty we are facing is when USB3.0 is active , USB2.0 does not work for the downstream devices (HUB enumerates as USB2.0 but not its downstream device).

so in the point 3 the device does not enumerate as USB3.0 and USB2.0 so we are not able to switch the mux .

so when we disable USB3.0, the USB2.0 lines of the downstream works fine.

We have also provided enough power for the USB HUB and its devices.

Regards,

R.Rohith yadav

Hi Rohith,

Can you confirm if the USB 2.0 downstream ports of the hub work if a USB 2.0 device is attached?  Is the problem that a USB 3.0 device is not being recognized in USB 2.0 mode or do the USB 2.0 ports not work at all when USB 3.0 is enabled?

Thanks,

JMMN

Hi ,

our downstream device is completely conneected to the HUB in a single board, even when USB upstream port of teh HUB is connected to USB2.0 port the USB2.0 lines of the HUB does not work, only aftetr disabling the USB3.0 in S\W, the HUB's 2.0 downstrem lines are working.

yes the USB2.0 does not work when the USB 3.0 is enabled

Regards,

Rohith

Hi Rohith,

It sounds like the embedded downstream device is still seeing the USB SS terminations on the downstream ports of the hub even when they are disabled. Can you confirm if an external USB 2.0 only device can be successfully connected to the hub when the USB 3.0 is enabled?

Regards,
JMMN

Hi JMMN,
We have checked the USB2.0 only device and found that it works properly without any issue.

i also have few other questions,
1. do you have any revision change for this HUB(TUSB8043RGCT)?
2. do you have any tool to read/write the registers in the HUB using USB interface

Thanks and Regards,
R.Rohith yadav

Hi Rohith,

1. No, there is no revision to the TUSB8043

2. The registers can only be set by I2C or SMBUS.

Can you confirm that after the TUSB8043 and embedded USB 3.0 device are connected to a USB 3.0 host, VBUS toggles low for the hub and device before the host connection is dropped to USB 2.0 only?  This may be why the USB 3.0 device is not appearing at USB 2.0 speeds, it may think it is still connected at USB 3.0 speed.  Also, please confirm the device between the type C port and the upstream port of the hub removes the superspeed terminations when the type C port is connected to a USB 2.0 only port.

Regards,

JMMN

Hi JMMN,

we have tested the VBUS supply from the type-C connector and did not find any togglling or fluctuation in the power supply, as you acn see in the below image.

and i would like to confirm that even after removing the USB MUX(the device between the type C port and the upstream port of the hub) and connecting the device to USB2.0 host, we have the same behaviour i.e., the USB2.0 signals dont work.

the USB 2.0 in the downstream of the HUB works only if the USB3.0 is disabled by the firmware of the embedded device of the HUB

Thanks,

R.Rohith yadav

Hi Rohith,

It sounds like the embedded device is not able to detect when the TUSB8043 removes its rx terminations and enters USB 2.0 mode. When the device is supposed to transition from USB 3.0 to USB 2.0, can you confirm that it is in an active power state (U0/U1/U2) and that VBUS toggles to the device? If the device is in U3 power state and VBUS remains on during the transition, the device may not properly transition to USB 2.0 mode.

Regards,
JMMN

Hi JMMN,

I have a few question,

 1. What do you mean by transition from USB3.0 to USB2.0 mode, once our device is connected to USB3.0 Host, we enumerate the device in USB3.0, we dont transition to USB2.0 mode. 

 2. This problem occus only in downstream port of HUB, The upstream port USB2,0 works properly.

 3. Do you have any method to test the power state and VBUS signals, we cannot check it as the device is not enumerating in USB2.0 at all.

Thanks,

R.Rohith yadav 

Hi JMMN,
do you have any updates on this issue.

Thanks,
R.Rohith yadav

1. / 2. When the upstream port of the hub disconnects from a USB 3.0 host and connects to a USB 2.0 host, all the downstream USB 3.0 devices should drop and reconnect at USB 2.0 speeds. The issue is that the downstream device is not transitioning from USB 3.0 to USB 2.0. It is remaining in USB 3.0 mode.

3. Can you probe the VBUS / power source to the downstream device on the board? it should toggle low when the upstream port of the hub is disconnected from a USB 3.0 host and connected to a USB 2.0 host.

Hi JMMN,

The power supply for the embedded deivces on our board are direct 5V supply from the USB host, so this voltage comes directly from our PC.

and we have this problem even when we connect the board directly to the USB 2.0 Host. so, in that case we dont have any switching between USB3.0 and USB2.0

Thanks,

R.Rohith yadav

Hi JMMN,

any updates on this issue.

Thnaks,

R.Rohith yadav

Hi JMMN,

do you have any updates on this issue.

Thnaks,

R.Rohith yadav

Hi Rohith,

This device has been implemented in many Type-C applications and we haven't seen any problems like this. Can you test asserting the PD of the mux switch between the Type-C connector and the upstream port of the hub? I want to determine if the hub is falsely detecting RX terminations on the upstream port.

REgards,
JMMN

Hi JMMN,

We have tested the boards by asserting the PD of the mux switch, still the downstream port USB2.0 is not detecting.

we have also tested by removing the mux switch and still the downstream port USB2.0 lines dont work.

Thanks,

R.Rohith yadav

Hi Rohith,

Without additional information on what states the device or USB hub are entering during the error mode, it is difficult to suggest a fix or workaround. We have many customers using the TUSB804x products with permanently connected USB 3.1 devices that are not seeing similar issues. This appears to be an application / implementation issue, not a silicon issue.

Regards,
JMMN