TUSB2036: Problem to use PORT1 as USB RNDIS support

Chendjou Merlin Claude

Part Number: TUSB2036

Tool/software:

Hi,

I am encountering a usage problem on PORT 1. 
The design uses 3 permanently connected ports: 
- PORT 1: Connection to equipment integrating embedded Linux with USB configured as Ethernet via USB (RNDIS).
- PORT 2:  USB-Serial connection using a CP2102 circuit which works perfectly. 
- PORT 3: Using a Lithium battery charger circuit. USB communication is only used to determine the maximum charging current.

I am currently experiencing a communication problem on PORT 1. The USB connection is detected and the RNDIS driver is loaded but communication is not taking place.
 If I disconnect the USB RNDIS from the HUB and connect it directly everything works. It is clear that the problem is with the TUSB2036 HUB.

I am adding my electronic diagram here if you can help me identify the problem.
Thanks in advance, 
Best regards,

8 months ago

0 Brian Zhou 8 months ago

TI__Guru*** 146055 points

Hi Chendjou:

Can you upload schematic again (PDF)?

Do you have datasheet for RNDIS?

Best

Brian

0 Chendjou Merlin Claude 8 months ago

Prodigy 40 points

Hi,

That's the shematic circuit in pdf https://drive.google.com/file/d/1qHjkgGF-MgP1yflCYxlRaeQW99AW9fM7/view?usp=sharing

For the RNDIS, the device use USB 2.0 stack usb linux embedded https://elixir.bootlin.com/linux/v6.12.6/source/drivers/usb/gadget/function/f_rndis.c#L374

Sorry but i don't have more information.

Best regards,

0 Brian Zhou 8 months ago in reply to Chendjou Merlin Claude

TI__Guru*** 146055 points

I 'm working on schematic review and will send feedback by tomorrow.

Best

Brian

0 Chendjou Merlin Claude 8 months ago in reply to Brian Zhou

Prodigy 40 points

Thank you very much in advance.

0 Brian Zhou 8 months ago in reply to Chendjou Merlin Claude

TI__Guru*** 146055 points

I can not access google drive from TI laptop, can you accept my friendship request and send by private message?

Best

Brian

0 Chendjou Merlin Claude 8 months ago in reply to Brian Zhou

Prodigy 40 points

hello,

Please find the file attached.

https://jmp.sh/s/qZCdhLo6djgW5iDbHH5f

https://we.tl/t-S7K0fw5Vui

Best regards,

0 Brian Zhou 8 months ago in reply to Chendjou Merlin Claude

TI__Guru*** 146055 points

Can you just upload PDF here or send to me by private message without any link?

the above link got blocked by TI site

Best

Brian

0 Brian Zhou 7 months ago in reply to Brian Zhou

TI__Guru*** 146055 points

I reviewed schematic, does CPU need Vbus detection on Port 1?

Best

Brian

0 Chendjou Merlin Claude 7 months ago in reply to Brian Zhou

Prodigy 40 points

Hello Brian,

Yes the CPU need Vbus detection. On the schematic, it's USB_DETECT_PA16 pin that is used for detection.

The detection is done by the CPU when connecting USB because I can see it via the Debug messages of the Linux Kernel. On the Machine Host side in windows 10, I can also see that the USB Ethernet RNSDIS driver is mounted but the communication is not present. As already explained, if I bypass the Hub circuit TUSB2036VRF and make the USB connection directly on the CPU everything goes well.

Best regards,

0 Brian Zhou 7 months ago in reply to Chendjou Merlin Claude

TI__Guru*** 146055 points

Can you force USB_DETECT_PA16 pin high all the time?

usually USB_DETECT_PA16 should be connected to TUSB2036 port 1 Vbus .

Best

Brian

0 Chendjou Merlin Claude 7 months ago in reply to Brian Zhou

Prodigy 40 points

Hello Brian, 

Sorry for the late response. This pin is high all the time. The USB_DETECT_PA16 pin is a signal from a USB power supply divider bridge. So when I power up the electronics via USB, the USB_DETECT_PA16 is always forced high during the entire Linux boot process.
Best regards, 

Merlin,

0 Brian Zhou 7 months ago in reply to Chendjou Merlin Claude

TI__Guru*** 146055 points

ok, let me check schematic again.

Best

Brian

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TUSB2036: Problem to use PORT1 as USB RNDIS support