FEDEVEL
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elessargr , 02-08-2026, 12:29 AM

> do you have the 1.5kΩ pull-up resistor on the D+ line to indicate full speed?
No D+ of the ETH IC doesnt have any resistor on it. I dont believe I have seen a reference for it that is needed.

elessargr , 02-08-2026, 12:29 AM

I will do some check then with Wireshark tomorrow

elessargr , 02-08-2026, 12:29 AM

and share the findings

elessargr , 02-08-2026, 12:33 PM

okay so,
Also with the Wireshark, with USBpcap, it does not see the downstream IC "Device" for ETH. I tried to reset the port and device via the USBTreeView that I have and still nothing. Its only showing the second IC "Device" I have on the downstream port.

elessargr , 02-08-2026, 12:33 PM

So the through the USB port there isnt any communication or negotiation (handshake) that tries to be done and failing from the look of it from what I understand/seeing.

elessargr , 02-08-2026, 12:35 PM

- When plugged to a USB2.0 and the PC starts the PC sees only the one downstream IC (Port2) which is always in a USB2.0 from the HUB.
If I do rst of the HUB, by grounding pin11 of HUB, nothing changes.
- When plugged into a USB2.0 and the PC works and detect both downstream ports on the HUB (ETH & port2) then do a rst on the pin11 on the HUB the ETH gets lost again.

QDrives , 02-08-2026, 08:22 PM

Do you get the correct start-up (idle) signal?
https://www.youtube.com/watch?v=N0O5Uwc3C0o

elessargr , 02-08-2026, 08:41 PM

Well I need an oscilloscope to see the initiate phase I guess correct?
He talks for this (D-/+) at the 1:26-2min I think.

Any specific time to look at the video?

QDrives , 02-08-2026, 08:47 PM

Well, if the discovery does not start, you could simply use a multimeter.
The 'signal' he mentions at around 1:36. For your product, the D+ would have the pull-up (=full-speed or high speed).

elessargr , 02-08-2026, 09:01 PM

So pull-up we mean more than 0 🙂

elessargr , 02-08-2026, 09:01 PM

yes a multimeter I have

QDrives , 02-08-2026, 09:07 PM

In this video https://youtu.be/wdgULBpRoXk?t=360 you also see "idle state".
And yes, the differential voltage should be more than 0V.
If you only have 0V, you could add a 1.5kΩ pull-up to D+ and see if that fixes your problem.

elessargr , 02-08-2026, 09:51 PM

okay so I need to check the D+ if its 0V or more.
If its 0V I can put a resistor to pull-up the D+ to High-Speed.
This would not impact the SuperSpeed of USB3.0 correct?

Like the PCB works fine when I plug it to USB3.0 but having issues with USB2.0.

QDrives , 02-08-2026, 11:44 PM

The pull-up on D+ is just for USB 2.

elessargr , 02-08-2026, 11:53 PM

Then how can I avoid having issues and make it work for both USB2.0 and USB3.0?

QDrives , 02-08-2026, 11:57 PM

I though you said USB 3 works?
The pull-up is only for the USB 2 connection as it is on the D+ line and not on the super speed lines.

elessargr , 02-09-2026, 12:01 AM

Yes with USB3.0 there is no issue.
Even when PC is shutdown and we power it up then the PC detect the ETH IC.
The issue is only present when the I plug the PCB to a USB2.0 and then powering up the PC or I do a reset of the HUB IC.

QDrives , 02-09-2026, 01:07 AM

So measure D+ compared to Gnd (0V USB),
measure D- compared to Gnd (0V USB)
and measure D+ compared to D-.

elessargr , 02-09-2026, 04:54 PM

Here are the values with the tests I did.

USB2.0 USB1_D+ Measurement to GND
- 1.1- PC is power off. The USB1_D+ is 3V
- 1.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D+ is 0.11V. Port1 (ETH) not detected (not HS not FS). Not a proper state
- 1.3- PC is power on and after re-plugging the PCB the USB1_D+ is 0.004-002V. Port1 (ETH) detected as HS. Proper state

USB3.0 USB1_D+ Measurement to GND
- 2.1- PC is power off. The USB1_D+ is 0.11V
- 2.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D+ is 0.11V. Port1 (ETH) detected as SS. Proper state
- 2.3- PC is power on and after re-plugging the PCB the USB1_D+ is 0.011-017V. Port1 (ETH) detected as SS. Proper state

USB2.0 USB1_D- Measurement to GND
- 3.1- PC is power off. The USB1_D- is 0.012V
- 3.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D- is 0.012V. Port1 (ETH) not detected (not HS not FS). Not a proper state
- 3.3- PC is power on and after re-plugging the PCB the USB1_D- is 0.002V. Port1 (ETH) detected as HS. Proper state

USB3.0 USB1_D- Measurement to GND
- 4.1- PC is power off. The USB1_D- is 0.012V
- 4.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D- is 0.017V. Port1 (ETH) detected as SS. Proper state
- 4.3- PC is power on and after re-plugging the PCB the USB1_D- is 0.018V. Port1 (ETH) detected as SS. Proper state

elessargr , 02-09-2026, 04:54 PM

USB2.0 Measurement USB1_D+ <> USB1_D-
- 5.1- PC is power off. The USB1_D+/D- diff is 2.95V
- 5.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D+/D- diff is -0.000/0.000V. Port1 (ETH) not detected (not HS not FS). Not a proper state
- 5.3- PC is power on and after re-plugging the PCB the USB1_D+/D- diff is -0.000/0.000V. Port1 (ETH) detected as HS. Proper state

USB3.0 Measurement USB1_D+ <> USB1_D-
- 6.1- PC is power off. The USB1_D+/D- diff is 0.000V
- 6.2- PC is power on after shutdown and I have left the PCB plugged. The USB1_D+/D- diff is 0.000V. Port1 (ETH) detected as SS. Proper state
- 6.3- PC is power on and after re-plugging the PCB the USB1_D+/D- diff is 0.000V. Port1 (ETH) detected as SS. Proper state

QDrives , 02-09-2026, 09:59 PM

How come in 1.1 (and 5.1) that D+ is high?
1.2 is not correct, unless there is some other issue as well:
- Make sure you remove all "unknown devices" from your PC. You may want to show "hidden" devices too.
- Check that the PC is not giving you a message "unable to detect device".
Can you check D+ also with an oscilloscope? It does not need to be a fast one as we are only interesting in the initials sequence that runs at 12Mbit/s.

Do note that in 3.2, the voltage of D- **is** the proper state.

elessargr , 02-09-2026, 11:50 PM

btw which D+ you are talking about?
Because I have three.
- One between PC to MUX (MUX since I use USB-C)
- One between MUX to HUB
- One between HUB to ETH (This is what I measured. USB1_D+/-)

elessargr , 02-09-2026, 11:51 PM

> How come in 1.1 (and 5.1) that D+ is high?
No idea 🙂

elessargr , 02-09-2026, 11:55 PM

> 1.2 is not correct, unless there is some other issue as well:
> - Make sure you remove all "unknown devices" from your PC. You may want to show "hidden" devices too.
I dont have any unknown or hidden devices 🙂

> - Check that the PC is not giving you a message "unable to detect device".
I havent seen anything. Also it doesnt shows anything plugged to port 1 under the USBTreeViewer which would be showing something if there was an issue with the communication. I had a similar issue on 2 previous version of my prototype.

elessargr , 02-09-2026, 11:56 PM

> Can you check D+ also with an oscilloscope? It does not need to be a fast one as we are only interesting in the initials sequence that runs at 12Mbit/s.
I dont have one 🙁
I will ask a friend to see if he can check this for me. Can you share more details what to look for this so I can tell him?

elessargr , 02-09-2026, 11:58 PM

> Do note that in 3.2, the voltage of D- is the proper state.
hmm interesting. So if this is on the proper state it should be detected though no?

QDrives , 02-10-2026, 01:33 AM

The D+ between hub and ETH, unless your hub itself is not detected.

QDrives , 02-10-2026, 01:35 AM

You can see that in the videos I provided a link to.
It is the D+ going high, and then the process starts... at least, it should start.

QDrives , 02-10-2026, 01:35 AM

No, D- should be low and D+ should be high.

QDrives , 02-10-2026, 05:09 PM

What you could also do:
When the PC does not detect the ETH via USB 2: attach a 1.5k...3k3 resistor between 3.3V and D+.
If it then detects the ETH, you may want to see if added the resistor 'permanently' fixes the problem.

elessargr , 02-11-2026, 05:06 PM

I will try to do this carefully over the weekend.
The thing is that if I place this resistor the ETH would work also if I use USB3.0? I think we said no right?

QDrives , 02-11-2026, 07:31 PM

No no. USB 3 should not be affected by the pull-up resistor (to my knowledge).
In any case, the resistor test is only to see **if** that makes it being detected in USB 2 after power-up.

elessargr , 02-14-2026, 12:19 PM

okay so I managed to install a resistor 2.49k (0402WGF2491TCE) between the USB1_D+ and the pin40 (+3v3). Marked it in blue ont he PCB https://www.lcsc.com/product-detail/C25884.html

https://streamable.com/d447a8
https://streamable.com/pz58by

elessargr , 02-14-2026, 12:24 PM

It did do something new 🙂 .
USB_Tree_viewer is seeing something on port1 of the USB HUB but its failing to start as it says when I power up the PC and the PCB is plugged on it.
If I reseat it in USB2.0 its being detected without any issue.

Now though if I plug the PCB to a USB3.0 its showing similar error on the USB2.0 (HS) interface while the IC its actually detected in the USB3.0 (SS) interface. Similarly if I reset the PCB.

Screenshot attached.

QDrives , 02-14-2026, 04:12 PM

So we see that a pull-up has some effect.

The error 43 is probably that the ETH does not (no longer) work in USB 2 mode at that time.
Do any of the reference designs have the power switched on to the ETH? Or are some also like yours with the power to the hub in parallel?
Your hub does have a PwrCtlX pin....

elessargr , 02-14-2026, 05:39 PM

> Do any of the reference designs have the power switched on to the ETH?
> Or are some also like yours with the power to the hub in parallel?
I dont believe I have seen any to the ones I found online previously.
RTL8153B-VB-CG

The weird part is that this issue is only happening on the USB2.0 and only if its been left plugged to the computer. Otherwise it works fine

elessargr , 02-14-2026, 05:45 PM

> Your hub does have a PwrCtlX pin....
You mean the pin5 on the USB HUB (PWRCTL1/BATEN1) ?

Plus those two?
- PWRCTL_POL/SS_DN1 (pin21)
- FULLPWRMGMTz/SMBA1/SS_UP (pin36)

I dont use battery for this PCB to where its connected to if you mean that.

QDrives , 02-15-2026, 01:10 AM

Where does your power come from? All from the PC through USB?
Anyhow, I think you better check the signals with an oscilloscope.

elessargr , 02-15-2026, 10:51 AM

> Where does your power come from? All from the PC through USB?
Yes, only from the PC (host device).

elessargr , 02-15-2026, 10:51 AM

I am waiting for the lad that has an oscilloscope to do the checks and tell me the results

QDrives , 02-15-2026, 04:56 PM

How many boards have you got?

elessargr , 02-15-2026, 05:27 PM

4x in total.
2x of the previous prototype that has same layout and 2x of the latest prototype.
Both of them have the same issue with the USB2.0 on the ETH IC.

QDrives , 02-16-2026, 11:52 AM

So you can look with the oscilloscope both at one with pull=up resistor and one without it.

elessargr , 03-08-2026, 09:39 AM

okay so, update here.
The lad that has the oscilloscope was able to do some checks and mentioned to me that there isnt anything abnormal in the D+/D- values from what he can see during the cold start in this configuration that I have.

elessargr , 03-08-2026, 09:39 AM

It happen also to have the USB-ETH adapter as an individual PCB with the same parts as we were doing some test prior, on an older prototype version, and when it was power up after a cold start it was detected without issues under a USB2.0.

elessargr , 03-08-2026, 09:39 AM

So this weird state its probably coming from the USB HUB (TUSB8020BI). We are thinking that it has to do with the power coming from the HUB IC and it may being able to get configure with the PWRCTL pins.

elessargr , 03-08-2026, 09:41 AM

Not sure if the PWRCTL can be configure in a way that once the HUB IC is waken up then it powers up the downstream port ETH IC.

QDrives , 03-08-2026, 07:10 PM

The power control pins do not power your ETH directly. You need a "load switch" for that.

elessargr , 03-15-2026, 10:47 AM

I see,
Any recommendation how I can do this or schematic?
I assume I need to use the pwrctl pin and something close to this.

QDrives , 03-15-2026, 04:08 PM

Pick one from these: https://www.digikey.nl/en/products/filter/power-management-pmic/power-distribution-switches-load-drivers/726