how does PC communicate with FPGA?

Nov 10, 2013 2 Replies

Hi,



I am unable to understand that how a PC communicate with FPGA. I have used Xilinx software to implement codes and then connected a USB cable to Xilinx test kit that did all jobs for me. Of course I assigned the chip pins with the signal names through Xilinx software itself. I am unaware what happens after I connect the USB cable to the kit. Please tell me what devices are in between the PC and the chip in the kit and how does the PC communicate w ith the chip or loads the design into the chip?



thanks Koyel


Most Xilinx kits use some sort of FTDI USB chip. You should be able to find the schematic for your kit on the Xilinx site.

Gabor

The design is loaded into the FPGA through a synchronous serial connection. There should be some Xilinx data sheet that describes the process. If they haven't changed things since I last really paid attention that synchronous serial connection can be used by a processor (on-board or external) to push a bitstream into the FPGA, or it can be used at boot up for the FPGA to suck a bitstream out of a serial flash chip.

In a production system with a separate microprocessor, you can keep the FPGA design in the processor flash memory, and load the FPGA from the microprocessor -- Xilinx has app notes that detail that process, too. I remember doing that during a period when the biggest Xilinx FPGAs were quite a bit bigger than the biggest Xilinx serial flash chips, and 'big' microcontrollers all tended to come equipped for external flash.

Tim Wescott Wescott Design Services http://www.wescottdesign.com

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