TUSB2077A: TUSB2077A device unknow

Coumba NDIAYE

Part Number: TUSB2077A

Hello,

I use two TUSB2077A to have 12 USB ports on my deisgn. The first TUSB2077 works perfectly but for the second one I got “Unknown USB Device".

If I pull the reset to GND for the second device I detect dowstream USB ports connected to it but I have a "Power surge on the USB port" message.

The reset only work for a while, and if I power off and on the board again the “Unknown USB Device". message is back.

Does anyone have idea to solve this problem?

Thanks,

over 2 years ago

0 Brian Zhou over 2 years ago

TI__Guru*** 145215 points

so U3 is first hub, U5 is 2nd hub?

whch downstream port is connected to 2nd hub?

Regards

Brian

0 Coumba NDIAYE over 2 years ago in reply to Brian Zhou

Prodigy 10 points

Hello Brian,

Yes U3 is first and U5 second. Downstream 6 of U3 is used for the second hub.

0 Brian Zhou over 2 years ago in reply to Coumba NDIAYE

TI__Guru*** 145215 points

is this bus powered? do you have vbus switch for 1st hub downstream port?

Regards

Brian

0 Coumba NDIAYE over 2 years ago in reply to Brian Zhou

Prodigy 10 points

Hi Brian,

All hubs are powered by an external 5V (I don't use or connect my laptop's USB vbus) and 3V3 step-down, first hub has downstream ports 1-5 powered and working, downstream 7 connected to the FTDI is also detected, it is just downstream 6 connected to the second hub which was not detected.

And when the second is detected (by pulling its reset) I get the message "the power surge" and I can see it with the external 5V power supply that there is a surge greater than 1A for one to two seconds.

I have no idea why the second hub is not detected and why I have this surge even though no downstream is connected to a device.

Best regards,

0 Brian Zhou over 2 years ago in reply to Coumba NDIAYE

TI__Guru*** 145215 points

1: you need to set power control/overcurrent for port 6 as well.

2: max current for each downstream port is 500ma.

Regards

Brian

0 Coumba NDIAYE over 2 years ago in reply to Brian Zhou

Prodigy 10 points

Hi,

What do you mean? I set OVRCUR6 hub1 on high and hub 2 is not power by bus but by local supply. Downstream 7 hub1 is on the same configuration than the 6.