Other Parts Discussed in Thread: TUSB8044
Tool/software:
I am using a TUSB8044A Hub and utilizing all 4 downstream ports. Ports 1 and 2 are connected to USB type A (USB3) connectors and Ports 3 and 4 are going to 2 different USB devices that are embedded on the same pcb. Downstream 3 has a LAN7800 ethernet device (USB 3.0) and downstream 4 has an Audio Codec chip on it (USB 2.0)
Since Ports 1 and 2 are exposed to the user for pluggable devices i have those VBUS' controlled via load switches while the embedded ports are not going through switches.
When I power on the TUSB8044A a USB tree sees the 2.0 Hub and the 3.0 hub. The Audio codec comes up perfectly on downstream 4 under the USB 2.0 hub, but the LAN7800 on downstream port 3 flaps under the USB 3.0 hub. It goes on and off the the bus roughly every 7-10 seconds. When this happens the audio codec device still remains connected and working properly.
When I get different USB3.0 devices and plug them into the type A connectors they show up on a tree view under USB 3 SS and those devices work great. When i take a LAN7800 evaluation board and plug into those ports i see the same flapping issue. If i take that same LAN7800 and connect it to the Type A ports via a USB 2.0 cable it works fine.
If i take that same LAN7800 eval board and plug it in directly into a PC instead of going through my board then it works fine.
Other note: If i take the TUSB8044 Eval board and plug in the LAN7800 eval board in everything works fine. 205-3827-0.PDF
