tusb8041: GRStz pin explainationi

Niranjan Madhavan

Intellectual 605 points

Other Parts Discussed in Thread: TUSB8041

Hi,

I am on bringing up the board. But I am getting "unknown device" when connecting to the computer.

Correct me if I am wrong:

If GRSTz is low, the chip will not work. The pin needs to be high (higher than 2V to get the circuite working right?

I am using a POR circuit for the powering on the circuit initially. I am using a POR circuit to be designed for Open drain reset pins but GRSTz pin is a pus pull type pin. Would that be the reason, the device is unrecognizable when I am connecting to the laptop port?

schematic1122.usb pdf.pdf

over 10 years ago

0 Jose Carlos Gil over 10 years ago

TI__Genius 9315 points

Hi Niranjan,

Please make sure that timing requirements and power-up sequence are met. Refer to page 11 on datasheet.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

I cannot control 3.3V and 1.1 V stability. So I have a POR which triggers the system after 140 ms, after both power are stable. So, it should be way beyond the timing requirement right?

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Yes, you're right but remember that this pin has an internal pull-up resistance, so, you might need to add 1uf capacitor in series to GND. Depending on the supply ramp of the two supplies the capacitor may have to be adjusted.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

I believe I did tried that. but no luck

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Can you share your schematic to review?

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

I added a pdf on my beginning question right now.

Just schematic of USB hub is good enough right? Or I dont have problem in giving schematic of the full circuit

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Schematic of the HUB is OK, I'll review and will come back with any suggestions I may have.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

usb_pdf.pdf

"1122.usb pdf.pdf " is the schematic file on my first post. Or attached usb_pdf.pdf is also the same

0 Jose Carlos Gil over 10 years ago in reply to Jose Carlos Gil

TI__Genius 9315 points

The schematic looks fine, I will recommend to change 10K pull-down resistors to 4.7K resistors, although these resistors are not the problem.
Please remove pull-up resistor on GRSTz pin (R68) and also remove U23, U24 & U25 which I assume are ESD protection just to check if this is causing some kind of interference, some times those devices interfere with the enumeration.
Is R1 9.53K?
Please let me know your comments after these changes.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

Yes R1 is 9.53k

Pullup resistor at GRTz is a DNI so it is not installed. I just kept them for debugging purpose.

Yes you are right, U23, 24 and 25 are ESD diodes and Its a good catch. thanks let me try removing them.

Is there any mix ups in my pinouts in micro B?

0 Niranjan Madhavan over 10 years ago in reply to Niranjan Madhavan

Intellectual 605 points

I removed ESD diodes, but no luck.

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Pinout of MicroB looks fine.
You have swapped SS lines but it's ok.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Niranjan Madhavan

Intellectual 605 points

Hi Jose,

I got two updates.

I tried to trigger GRTz pin manually may be after couple of seconds after vdd stable, but still got the same result.

I connected a USB 2.0 micro B connector and still got same "unknown device" on widows 7.

Is there any way I can factory reset the registers? or check what is inside the configuration registers ?

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Hi Niranjan,

We have a tool to check the registers on the external EEPROM if using for custom configuration, but if no EEPROM is used, the internal registers should be without any change.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

Could you share that tool for EEPROM, I have the option to connect the EEprom on my board. In-fact, we are looking for EEPROM for final production version to get USB 3.0 certification.

what is 3 One Time Programmable (OTP) Configuration? Is it same as EEPROM? I have not done any OTP on my IC. Is that something the problem? Currently, the IC is just placed on board from the package. Do registers need to be configured first by OTP to work or it is manufacturer configured ?

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Hi Niranjan,

I will send by mail the tool.
The TUSB8041 can be custom programmed by eFuse (OTP) but these configurations are not needed for the IC to work, the device should work just fine as is.

Regards.
JC

0 Jose Carlos Gil over 10 years ago in reply to Jose Carlos Gil

TI__Genius 9315 points

Niranjan,

Have you tried to use different cable to connect the upstream port to the computer? A shorter one?
Is your trace impedance of 90 ohms?

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

Yes I tried longer and shorter cables.

And yes the trace impedance is designed for 90 ohms. Is there any way we can measure on board?

The stack up is attached. And all the USB lines are in top layer with width 8 and separation 6.

HR3_Stackup (002).pdf

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

I have tried to send you the EEPROM programmer to your registered email but it was rejected, can you share another email? preferably corporate mail.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

nmadhavan@perceptron.com

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

I have sent the file.

I have shared your schematic with a colleague and he didn't found anything wrong either.
Can you please check that the USB 2.0 lines are not swapped.
Those are not swapped on schematic but there may be physically swapped .
Are you connecting the upstream port of device to a USB3.0 or USB2.0 port of computer?

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

upstream.zipI did not swapped the USB 2 lines. The usb 2 lines are taken around the pin.

I am attaching the upstream lay out screenshot.

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

Are you connecting device to USB2.0 or USB3.0 port in computer?

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

The port is marked SS and the driver shows it is USB3.0 hub.

And TUSB8041RGCEVM (eval board) is working properly on that port.

How can I test the chip is broken?

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

The best and fast option to verify if the chip is broken is to replace it on the board, if you have the EVM and it's working properly I suggest to switch both chips and then test the boards.
Please let me know results.

Regards.
JC

0 Niranjan Madhavan over 10 years ago in reply to Jose Carlos Gil

Intellectual 605 points

I am not able to swap the chips. But I replaced the chip with a new one, but still getting exact problem. I am able to turn it OFF and ON by manually triggering at pin 50, but detecting it as a unknown device.

It could be a design issue. My high speed traces are bad? there is no way to check it right?

I am using a connector which is vertical to the board for up stream port, which may be causing the problem!?

0 Niranjan Madhavan over 10 years ago in reply to Niranjan Madhavan

Intellectual 605 points

I think I got the reason for the issue. It is somebody removed the resistor R1 from the board. I am looking into where in the loop has gone bad!. I apologize for this silly mistake. It is not reflected in BOM, build process, initial check etc. So need to figure out, how it is removed.

0 Jose Carlos Gil over 10 years ago in reply to Niranjan Madhavan

TI__Genius 9315 points

A few comments above I have asked about R1.

Regards.
JC

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tusb8041: GRStz pin explainationi