Schematic Capture

If you are going to design your circuit using Xilinx library parts rather than Mentor Graphics generic parts in Design Architecture or da, start Design Manager first.

1. Make a directory for this class and change to it. Invoke Design Manager by entering pld_dmgr in a Unix shell.
2. To start da from Design Manager, click on the icon pld_da in the Tools window on left. Refer to the information in the section on Schematic Capture for information on using da.
3. To start a new design (or open an existing design) in da, click on the icon OPEN SHEET in the session_pallet on the right. A dialog box named Open Sheet will come up. Enter a component name and click on OK to open a blank sheet.
4. To change to the library pallet for the Xilinx library parts, go to the Menu bar and select Libraries and XACT_LIB. The session pallet should have a header XACT_lib_Main_Menu. Click on UNIFIED LIB then XC4000 LIB then ALL PARTS to get to each individual component. The functionality of each component in the list is described in detail in the Xilinx online documentation.
5. Build the full adder as shown in Figure 7. When working in da, you can use the Menu bar, the right mouse button, the softkeys at the bottom, the session pallet or the center mouse button. Draw a question mark with the center mouse button to see a list of commands that you can execute with mouse strokes.
6. The highest level of your design which will be downloaded onto the Xilinx chip must use the buffers and ports shown in the figure. These components are ibuf, obuf, ipad and opad. The property values inside the ports, for example P60, indicate this port is assigned to pin #60 on the Xilinx chip. Refer to Table 1-2 and Table 1-4 in Chapter 1 of the Xilinx Hardware & Peripherals User Guide for pin location and function. pin location and function.
7. Check the circuit by typing check then save the sheet.

       
   Figure 6: Using a Full Adder As a Component
   Figure 5: Full Adder
   

8. If you want to make this circuit into a symbol, in the pull down menu click on Miscellaneous and Generate Symbol... then OK. A sheet will open with a symbol in it. Check the sheet and save it. You could open a new sheet, put just this symbol in it, add the Xilinx ports and buffers to the symbol and download it to the Xilinx board. But you'll probably use this component in a larger design so you would add the Xilinx I/O parts at the highest level as shown in Figure 5. Also note that if you have created a schematic using VHDL code and AutoLogic II it might already have these buffers. Don't add another buffer in series, you'll get an error.