TUSB542: USB 3.0 device not detected

Nanjunda

Why do you have resistors on SuperSpeed signal lines?

Have you tried other USB3.0 devices and have you tried both Type C orientation?

Please probe the SuperSpeed signal lines, are you seeing LFPS when storage device is plugged into TUSB542?

Thanks
David

Hi David,

As this is a proto model, we have provided options to transmit and receive lines; just in case to make wiring.

We have tried everytime with 3.0 working storage devices and we have tried both orientations.

We will check the LFPS on Supespeed signals and let you know.

Thanks & Regards,

Nanjunda M

Hi David,

I did not see any LFPS on SS signals.

Do you have any suggestions on how to move further.

Thanks & Regards,

Nanjunda M

Nanjunda

Where did you probe the LFPS signal, between host and TUSB542 or between TUSB542 and Type C connector? If it is between TUSB542 and Type C connector, did you check both TX/RX1 and TX/RX2?

1. Please check 1.8V to TUSB542 and make sure it is powered correctly
2. The connection looks to be correct between Type C connector and TUSB542, please check the connection between the host and TUSB542, TX is connected to the host transmitter and RX is connected to the host receiver
3. Remove R276 and manually change SEL pin, set to high and try both orientation of Type C cable, set to low and try both orientation of Type C cable.

Thanks
David

Hi David,

Seems like we had some software issue with configuration. Now we are able to detect the USB3.0+USB2.0 on one side.

This brings us with one more issue, where the Mux selection IC (CC Controller) is not able to detect the reverse direction. (Initially for experimentation we did wiring of the D+ and D- signals)

We have observed the below things:

1. Input to  CC1 & CC2 are toggling when nothing is connected and when the USB is connected they are either high or low based on the USB insertion.

2. The DIR pin is constantly high

3. ID pin is also Constantly high

4. VBUS_DET pin is at 0.48V (other side of the pull-up resistor is 5V)

Could you please let me know how to debug this issue?

Thanks & Regards,

Nanjunda M

Nanjunda

Looking at the schematic, I noticed you have CC1 of TUSB322I connected to Type C connector CC2, and CC2 of TUSB322I connected to Type C connector CC1. 

The CC1 and CC2 are used to resolve cable orientation and twist connections to establish USB data bus routing. Only one CC pin is connected through the cable to establish signal orientation and the other CC pin is VCONN.

The standard USB Type-C cable is wired such that a single CC wire is position aligned with the first USB SuperSpeed signal pairs (SSTXp1/SSTXn1 and SSRXp1/SSRXn1) – in this way, the CC wire and USB SuperSpeed data bus wires that are used for signaling within the cable track with regard to the orientation and twist of the cable. So CC1 should be aligned with SSTXp1/SSTXn1 and SSRXp1/SSRXn1 but this is not case right now.

Thanks

David

Hi David,

The connection was reversed based on the input instruction provided in the TUSB542 datasheet (Reference schematic).

Could you please verify that ?

Thanks & Regards,

Nanjunda M

hi
any update on this?

Nanjunda

To minimize crossing in routing the USB3 SS signals to the USB Type C connector, the connection of CC1 and CC2 to the TUSB322I is swapped.
When swapping the CC1 and CC2 connection, the CABLE_DIR register will also be reversed (0 = CC2 and 1 = CC1). So please check that the DIR pin of TUSB322I is appropriately driving the SEL pin of TUSB542.

Are the other side which does not work, do you see LFPS?

Thanks
David

Hi David,

As said before we have below observations with TUSB322I:

1. Input to  CC1 & CC2 are toggling when nothing is connected and when the USB is connected they are either high or low based on the USB insertion.

2. The DIR pin is constantly high

3. ID pin is also Constantly high

4. VBUS_DET pin is at 0.48V (other side of the pull-up resistor is 5V)

Could you please let me know how to debug this issue?

Thanks & Regards,

Nanjunda M

Nanjunda

How are you controlling VBUS? VBUS can only go high after CC pin detection and debounce.

Thanks
David

Hi David,

We are not controlling the Vbus, VBUS will be always available for the device as our requirement is to have the interface as Host only.

Thanks & Regards,

Nanjunda M

Also we tried probing the DIR pin with pull-up resistor removed, we observed high on this pin all the time.

Regards,

Nanjunda M

Nanjunda

VBUS_TYPE_C is connected to 5V, where does 5V get generated? You need to make sure VBUS can only go high after CC pin detection and debounce per the spec, otherwise the CC detection logic will not work properly.

Thanks
David

Hi David,

Seems like this was the issue, we are now able to see the toggling of the DIR pin with respect to the position of the Connector position.
I couldn't find this dependency info on the datasheet.
Could you please let me know, is it ok to leave the VBUS_det pin floating w.r.t. our design?

Thanks & Regards,
Nanjunda M

Nanjunda

No, the system VBUS voltage must be routed through a 900-kΩ resistor to the VBUS_DET pin on the TUSB322I device.

Thanks
David

At present I do not have any alternate to delay the VBUS voltage to VBUS_DET on TUSB322I, so what would be the effects of floating the VBUS_DET ?
Could you please elaborate.

Thanks & Regards,
Nanjunda M

Nanjunda

VBUS_DET is needed to make sure VBUS is at vSafe before enabling VBUS. So if leave floating, VBUS will not get enabled.

Thanks
David

Hi David,

If you look at our schematics, we are directly passing the 5V(generated on board) to VBUS, so there is no enable pin over here. We do not have any control over the VBUS. 

Also to be clear we are connecting only passive devices to the Type-C port.

So could you please tell me now, whether its going to matter particular to my case?

Thanks & Regards,

Nanjunda M

Nanjunda

What do you mean "passive devices"?

You need to isolate the VBUS by using a VBUS switch such as TPS25910 so that CC detection can be done first without VBUS.

Thanks
David

Passive device - I meant to say the memory sticks(Pendrive), which do not supply power to the connector.

Thanks
Nanjunda

Nanjunda

The memory stick get its power from VBUS. But the issue here is that you can't pass 5V directly to VBUS, you need to have a VBUS switch controlled by the TUSB322 to isolate the VBUS.

Thanks
David

To the Type-C connector VBUS is always connected and its always present
But why do we need to Isolate the VBUS? Why do we need VBUS switch?
Could you please explain?

Thanks & Regards,
Nanjunda M

Nanjunda

VBUS can only go high after CC pin detection and debounce per the spec, otherwise the CC detection logic will not work properly. If you have 5V connected permanently VBUS, how do you plan to control the VBUS?

Thanks
David

David,

I agree with what the spec says, but looking into the application I'm using whether we need to control this VBUS is my doubt.

One more doubt is with the "CC detection logic will not work properly" statement, whether you are saying this particular to the TUSB322 IC or you are saying that the Connector also will follow the same rule?

Thanks & Regards,
Nanjunda M

Nanjunda

If you are designing USB Type-C system, then you need to provide VBUS switching capability, otherwise the design is a spec violation. TUSB322I follows the same spec in its implementation.

Thanks
David

David

 

I completely agree with your point that the present design is violating the Type-C spec.

But can we make it to work with this design is the question. 

Could you please help us with that.

 

Thanks & Regards,

Nanjunda M

Nanjunda

I can't provide a solution to a design that is out of spec.

Thanks
David