TUSB2077A Not Responding

Jerry Joseph

Other Parts Discussed in Thread: TUSB2077A

I have the TUSB2077A and it doesn't seem to respond to anything.

Reset is verified high after startup. Even tried pulling low then releasing after power up.

All OVERCUR lines are pulled high through 10k. All PWRON signals are disabled high.

6MHz clock verified.

PORTPWR and HUBCFG are both low.

One thing I didn't implement is 1.5K resistor from DP0PUR to DP0. Do I need this?

What else should I be looking at?

Thanks for your help.

Jerry

0 Greenja over 12 years ago

Guru 22270 points

Hello Jerry,

According to the USB specs, a pull up resistor is required for high speed USB. Did you try placing the resistor?

What is the output on the SUSPEND pin?

Thanks,

0 Jerry Joseph over 12 years ago in reply to Greenja

The suspend pin is low.

I did not try the resistor and I won't have access to the board until Monday.

Would the absence of the resistor cause the TUSB2077A to not respond? The HUBCFG pin does not go high.

Thanks,

Jerry

0 Elias Villegas M. over 12 years ago in reply to Jerry Joseph

Yes,

The lack of the 1.5K pull up will cause the hub to not respond.

Regards.

0 Jerry Joseph over 12 years ago in reply to Elias Villegas M.

Thanks for the feedback.

We installed the resistor and everything worked fine. This was my first USB app and I didn't recognize the importance of the resistor.

Jerry

Interface forum