I am testing my design on Xilinx ML402 board. I can send data from the PC to the FPGA board through the parallel port using LVTTL pin constrains. Header used is J6 at 3.3V. Problem is reading from the FPGA to the PC thorugh the parallel port. It doesn't seem to read anything, I measured the voltage on the header's lines when it is connected to the parallel port and it is 2.5V. When there is no connection to the PC, the voltage is 3.3V which seems OK. But why I can not read anything on my PC from the parallel port?
Thanks, Dan