Generating a Bitstream
Now that we have our final design, we have to get it into a form that we can put on our board. This is known as a bitstream; an (encrypted) file that represents our implemented design in its entirety.
Encryption
Having the bitstream encrypted is useful from a security perspective; while you may not want sensitive design files to get out, you can leave your bitstream lying around, and no one will be able to reverse-engineer the design it represents.
Generating a Bitstream
Generating a Bitstream
On the left-hand side, in Flow Navigator, under Program and Debug, click Generate Bitstream, then click OK.
This should hopefully take much less time than the implementation, as we’re not going through the flow, but simply packaging the result.
Eventually, you should hopefully get a pop-up that the run completed successfully - we’re good to go!
Generating a Bitstream
Either from Tools -> Run Tcl Script or from the command
line (shown below), run the impl_design.tcl script
% vivado -mode batch -source ../scripts/bitstream/gen_bitstream.tcl
Check the output logs for the line
write_bitstream completed successfully, and you should be good!
Putting a Bitstream on the Board
After this process, we should have a bitstream (located as top.bit in
vivado-walkthrough.runs/impl_1)
Debug Probes
While the .bit file is the primary output, some users may later
incorporate debug probes into their design; see
Appendix B: Using Debug Probes for more
details. In that case, we’d also have a top.ltx file that specifies
our debug probe configuration.
All that’s left to do is put this on our board - this is best done from the GUI.
Programming the Board
Ensure that your device is on and plugged in.
On the left-hand side, in Flow Navigator, under Program and Debug, click Open Hardware Manager.
You should initially have a banner at the top that says “No hardware target open”; click Open target, then Auto Connect. This will launch a “host” to connect to your device; you should see it show up on the left-hand side.
Once there, click Program Device in the banner (or from Tools) to program the device. Vivado should automatically identify the bitstream (and debug probes, if any) associated with your design; click Program.
Vivado will take a second to program the device, and then you should be good to go! For this design, this looks like the LEDs cycling through all gray codes when the switch is on (looks like the LEDs are all on, since it happens very fast), and pauses on a particular one when the switch is turned off.
Congratulations - you’ve just programmed a board with Vivado!
This is also where the portability of bitstreams comes in handy. If you need to program from a different device than you compiled with (perhaps because of license availability), you can simply transfer the bitstream (and possibly the debug probes), and open Vivado only with the hardware manager to program a device (which doesn’t require a license).