TUSB2046B: TUSB2046BIRHBR

Karthikeya RAM

Part Number: TUSB2046B
Other Parts Discussed in Thread: TUSB2036

Hello,

I have interfaced USB-HUB "TUSB2046BIRHBR", which has 4 downstream ports.
I need to use only 2 ports, remaining 2 ports I don't want to use in my project.

But when I check "Dmesg" logs unused downstream ports also show.

so how can I disable unused ports in USB-HUB.

whether unused ports (D+ & D-) signals required any pull-up or pull-down resistors to VCC & GND respectively.?

Please give an exact solution to my problem.

Regards

NIKHIL

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 243680 points

The TUSB2046B always has four active ports.

You would have to replace it with the TUSB2036. (Or just do not connect anything, and ignore those ports.)

0 JMMN over 2 years ago

TI__Guru 60865 points

HI Nikhil,

The TUSB2046B does not have the option to set ports to unused so that they are not reported to the host. TUSB2036 can do this using the NP3/ pin or the TUSB4020B can be used.

Unused ports should be tied together (DP and DM) and pulled low.

Regards,

JMMN

0 Karthikeya RAM over 2 years ago in reply to JMMN

Prodigy 60 points

Thanks for your reply.

So you mean to say we can't disable unused ports in USB-HUB (TUSB2046BIRHBR).

Regards

NIKHIL

0 Karthikeya RAM over 2 years ago in reply to Clemens Ladisch

Prodigy 60 points

Thank for your reply.

Yes sir as like you said i left unused down stream ports,but when i see USB-HUB logs in linux screen.
my 2 ports are showing its name but other 2 ports also showing in screen with "device not accepting address 58,error-71"
& "unable to enumerate USB device".

But i don't want message of unused ports so i want to disable it so that i don't want unused port .

please suggest me to achieve the same.

Regards

NIKHIL

0 JMMN over 2 years ago in reply to Karthikeya RAM

TI__Guru 60865 points

Correct, the unused ports cannot be disabled in the TUSB2046B. However, an unused port should not report an error - do you have DP/DM pulled low on the unused ports?

0 Karthikeya RAM over 2 years ago in reply to JMMN

Prodigy 60 points

NO i left DP & DM pins without any pull down to GND.

So Mr.JMMN , you want me to pull down to GND with some resistors (10K).

Regards
Nikhil

0 JMMN over 2 years ago in reply to Karthikeya RAM

TI__Guru 60865 points

Yes, it seems that the hub thinks there is a device connected to the unused ports and is trying to enumerate it and failing. Try pulling DP and DM low to prevent this.

0 JMMN over 2 years ago in reply to JMMN

TI__Guru 60865 points

We typically recommend 15K pulldowns on DP/DM, but if no devices will ever be connected to the port then 10K can be used.

0 Karthikeya RAM over 2 years ago in reply to JMMN

Prodigy 60 points

Okay thank you i will do the same and verify once.

i have one more issue here out of 2 down stream ports one of my down stream port is not get detecting.

Even i have verified whole section of 2 nd down steam port still device not get detecting.

NOTE:-

I can read even high (3.3v) at DP pin of 2nd down stream port.

still my USB-HUB can't detect the device.

so please suggests me what might be the issue

0 Karthikeya RAM over 2 years ago in reply to JMMN

Prodigy 60 points

Okay may i know what is the purpose of connecting 15k pull down to differential pair signal when it is connected to some device?

+1 JMMN over 2 years ago in reply to Karthikeya RAM

TI__Guru 60865 points

Downstream USB 2.0 ports require 15K pulldowns for normal operation. Some of the newer hubs integrate the 15K pulldowns into the hub chip, but the older hubs like the TUSB2046B require the external pulldowns be installed.

It sounds like your second hub port may have gotten damaged. Are you able to see this issue on multiple platforms?

Regards,

JMMN

0 Karthikeya RAM over 2 years ago in reply to JMMN

Prodigy 60 points

Yes only my first port is working.

The remaining 3 ports are not working.

0 JMMN over 2 years ago in reply to Karthikeya RAM

TI__Guru 60865 points

Do you see this same failure on multiple boards or just one?

If you are seeing the issue on multiple boards, can you provide the schematic?

I have sent you a friend request, you can send me the schematic directly if you do not want to post it.

Regards,

JMMN

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TUSB2046B: TUSB2046BIRHBR