I'm having some trouble using the USB-to-UART bridge on a KC724 board to communicate with a Raspberry Pi - I can send data from the FPGA to the Pi, but data sent from the Pi never appears on the FPGA. I've done the following:
1. Tried a design using the UARTlite IP and Debug cores - no data was received at the FPGA, and setting a trigger on rx_ibuf transition from low to high never triggers
2. Made a crude bit generator on FPGA and transmitted data with the correct UART "format" from FPGA to pi - I received data on the Pi as expected
3. Connected USB_TXD_O to USB_RXD_I of the FPGA - no data was received from the Pi, and no data made it back to the Pi from the FPGA
I've looked through both the UART bridge device manufacturer's data sheets as well as the Xilinx forums and general google searches, but with no luck.
Pin assignments and standards were copied from the master XDC for the board. I'm using Vivado 2015.1
Please let me know if any other information is needed.