Hello,
We are using TUSB2036 with 2 CM6571 usb audio codec and a joystick controller. The hub is buspowered, 3 permanently devices,
~EXTMEM is 1
~NP3 is 0
MODE is 0
DP0 is pulled up to Dp0pur via 1.2K
My schematic is attached. At the power up, only the joystick controller and hub (Generic USB hub) is recognized by Win7. The audio codecs are not recognized. But when i connect codecs to DM3,DP3 (joystick downstream), they are recognized.
Can there be a power issue?
The audio codecs have intel8051 in them to handle the usb protocol, and at the power up, the firmware of the codecs read the EEPROMs and get custom Product strings. When i watch the i2xc lines between the codec and the EEPROM, i see cracked bits on the oscilloscope.
By the way, the TPS2044 is not powered, the power to the downstream devices are all Vbus. I unplug the TPS2044 from PCB and make overcurr pins of the hub 3.3V.
How can the hub make the USB port of the PC supply necessary current (in my case it will be nearly 300 mA)? By looking at the permanent devices pins?
Thanks in advance.
