I'm trying to get my picozed to operate in USB device mode, and apart from the massive struggle with Petalinux kernel configuration, I'm starting to wonder if the hardware is not part of the problem as well.
According to page 74 of the USB phy datasheet:
The Vbus pin of the phy needs to be connected (with appropriate series resistance and bypass capacitance) to the +5V power coming from the host.
The jumpers on the carrier board allow for appropriate configuration in terms of Rvbus and Cvbus mentioned above, but diode D5 on the carrier board is preventing the phy from seeing the +5V from the host. I suspect that this will prevent it from enabling its pull-up speed-identification resistor on D+ which is what tells the host that a device is connected.
Can anybody confirm for me that their PicoZed+Carrier board is capable of operating in device mode? and if so can you share your linux image and/or kernel configuration options?