Schematic Design Entry in VHDL
- Open the ISE project navigator by double clicking on the icon
- Go to file Click new project, Type the name of the project in new project window and click next.
- Select device family, device, package, speed grade and design flow and click next in the design properties window.
- Click next and then click finish
- Click new source ( from Design pane, or project menu-> new source
- Click Schematic entry , Type file name, add to project, then click next
- Click finish
- A new schematic design entry window opens
How to draw schematic:
Under the categories in schematic drawing window, there are variety of symbols like counters, decoders, logic etc
Click on “Symbol info” in the middle left side window, A pdf file will open showing its working.
Here you do not refer in terms of TTL IC numbers, but talk in terms of various blocks.. The procedure for drawing is:
a. Select a category
b. Place the symbol (for TTL IC no. 74LS192 counter) on the workspace.
c. Draw wires for inputs and outputs
d. Place I/O markers for i/p, o/p pins, which you need externally
e. Place Vcc, and GND for input pins which are permanently HIGH or LOW. Ensure you draw wires before connecting i/o markers
f. i/o markers for i/p pin
g. i/o markets for output pinh. Double click the i/o marker for editing
9. Select 4-bit counter “cb4cled” by selecting counter in categories in symbols.
- Place wires on i/o and then place I/O markers
- Edit pin names double clicking on i/o marker.
- Use BUS Taps or I/O slice to bring only relevant signal to IO pin say 1 O/P out of 8 O/Ps of a shift register.
- Bus Taps and I/O markers are available on schematics window <- Bus & Taps
- After drawing click on Sources and processes tab to the left and double click synthesizer & run the schematic to check syntax error. Debug for errors if any and rerun.
- Goto Project-New Sources and click Implementation Constraint file. It will generate UCF file for your schematic.
- Click + beside file_name.vhd then click file_name.ucf
- In the processes tab click + on user constrain and double click edit user constraint to open blank ucf file. Type all the pin entries for the used i/o pin
- Double click implement design in process tab and debug errors if any.
- Connect the FPGA Kit to printer port of PC and connect the power supply to kit. Switch on the power supply.
- Double click Generate programming file.
- Run Configure Device (iMPACT)