My customer is having some trouble using the TUSB2077A chip:
Currently the part does not enable power to the downstream ports. The PWRON lines are still outputting high. The overcurrent lines are pulled up. There is a 750 us reset pulse sent to the chip. The suspend pin measures a low. The clock is running at 6MHz. The DP0 pin measures 3.3V. The HUBCFG pin measures low. The PORTPWR pin measures low. The PORTDIS pin measures high.
I am not sure what needs to be done to get the chip to enable the downstream ports.
I set the bus power pin high based on figure 9 in the TUSB2077A datasheet.
Regarding having trouble getting the hub started: I have attached scope captures of the reset / clock lines, and the reset / suspend signals. At power up we send a reset pulse to the hub, then the clock turns off for about 3 seconds while the hub is suspended, then the clock comes back. After this happens, the hub still does not enable power to any ports. In my scope captures the reset line is the green line, the clock and suspend signals are the yellow lines.
Any help would be appreciated.
Thank you!
