Downloading your BIT file to the on-chip FPGA PROM

This tutorial will teach you how to make download your design onto the chip such that you can turn the board off, and then turn it on again, and your design will be automatically downloaded and executed. Much better than constantly downloading the bit file!

The new Xilinx IMPACT tools make the process much easier than in the past, and also don't require a JTAG cable. Everything can be done right through the USB cable which you should already be familiar using.

Step 1

Open up the program IMPACT from the Start Menu. It is located in the Accessories sub-folder underneath your Xilinx ISE folder. Create a new project.

Step 2

Click the radio button that says "Prepare a PROM file". Click Next.

Step 3

On the next screen, make sure that you want to target a Xilinx PROM. The radio button should be checked by default, but make sure before clicking Next.

Step 4

Check the box that says "Auto Select PROM" and then click Next.

Step 5

You don't need to do anything on this screen. Press Finish.

Step 6

Click OK on the first little popup that shows up. The next screen will then prompt you to select a bit file to be put on the PROM. Click on the bit file you want to use, and press Open. After this screen, IMPACT will ask you if you would like to add another device file. Click No.

Step 7

Your screen should now look like the screen below. Highlighted on my screen in the middle left is some text saying "Generate File". Double click that.

Step 8

You have now successfully created a file we can download to the PROM onboard the FPGA. We now need to create a new project. ( No need to save the old project). Click File, New... Now check the radio button to "Configure devices using Boundary-Scan". This is the same as we have always done. Click Finish. Three prompts will come up. Press Bypass on all of them.

Step 9

I'm sure you've noticed everytime you program your FPGA that there are 3 chips that show up in IMPACT. The second one is the on-board PROM. The memory is non-volatile, meaning we can turn the board off, and the memory will be unaffected. Also, when we turn on the chip, the bit file in the PROM will be downloaded to the board for us. No more going through IMPACT!

Right click the second chip in the chain, and click "Assign New Configuration File"

Step 10

The PROM takes the file of type .mcs. If you clicked "Generate File" in one of the earlier steps, there should be a mcs file in your directory. Open that file. Again right click the second chip and press Program. A status bar should come up giving you details as to how far along the process is. Typically, it takes a few more seconds to program the PROM than the actual FPGA.

Step 11

In order to test that everything worked, power down your board and then power it back up. The bit file will be downloaded within a few milliseconds, and your design will be executed. Congrats! and hope this helped!