MAKING FRIENDS WITH A FIELD PROGRAMMABLE GATE ARRAY
items in the same general vicinity as I have in Figure 5.
Once everything is on the
screen, you can start wiring. You
can use the same cursor to wire
the project as was used to place
components. If you can't get the
wires to run in a neat manner,
you can always choose the line
cursor by clicking the line button
on the sidebar. Either way, simply click and hold over an input
and drag to an output.
Connect all the wires the
same as shown in the diagram.
Before you compile the file,
you need to rename the Input
and Output pins. After renaming
the pins to something logical —
like where they connect to the
display LEDs and Trigger — save
the file. Then click the <Max+plus
II> menu item and click on
<Compiler>. When the compiler
window pops up, click on start.
Once the compilation is complete, a pop-up will appear
informing you of any warning and/or error messages. A
second compiler message window will also appear. It will
contain any warning, error, or information messages generated by the compiler.
In this case, you will get a
green, "Not-gate pushback" information message. This message
means very little to our project. If
there is a red error message,
there is a convenient "Help on
Message" button available. Select
the message you are curious
about and then click the help button.
The compiler creates several
files. The .rpt file shows which
pins have been assigned as
inputs and outputs. The .pof file
is the file that is used to program
the FPGA. The compiler assigns
physical pins to your specified
inputs and outputs, but you will
probably want to change its
choices. I did, and if you do,
beware of the fact that the chip is
mounted to a board meant for
So, there are several multifunction pins that cannot be
used as input or output even
Figure 3. Truth Table for 7447.
bols for Gnd, Vcc, Input, and Output. This time, choose
the primitive (Prim) library. You will only need one Gnd,
Vcc, and Input. You will need 11 Outputs. It is possible to
copy and paste these just like the inverters. Place all
NUTS & VOLTS
Figure 4. Screenshot of MAX+plus counter circuit.