Download Protel Tutorial - Machine Intelligence Lab

Protel Tutorial
In this tutorial, we will use Protel to design an 8-bit counter using two 74’163 devices. This project will
show all of the requisite Protel functions. The circuit is not guaranteed to work J
Schematic Entry:
Wire tool
Bus Entry tool
Bus line tool
Net tool
Special symbols tool
Port entry tool
Firstly, locate the schematic libraries you need. For the 74’163 you will need the D_TTL.LIB
library. For the connectors you will need both DEVICE.LIB and D_DEVICE.LIB. Add these
libraries by clicking on “Add/Remove” in the upper left corner.
Select the D_TTL library and choose the 74HC163 device. Click “Add” to add two of the parts to
the sheet.
You will notice that the parts will have the designators “U?” on top and the name of the part
below. We will later change these to “U1” and “U2”.
We want a 8-bit output bus (to show how to use busses) so we will use the wire tool to extend the
eight outputs of both devices. Now, using the bus entry tool, add bus entries to the ends of each
wire. Now run a bus up through the ends of the entry symbols. Terminate it in a port symbol using
the port entry tool. After placing the port symbol, double click on it and change the name to
“D[0..8].”
Since busses don’t have any connectivity associated with them, we need to add nets to the wires.
To do this, click on the net tool bus before laying a net, press TAB. A dialog box will appear. This
will let you specify the net name you would like to place. Enter “D0”. Now place the net on a wire
(a small red dot will appear to show that it is connected.) By using the TAB key, Protel will
automatically increment (and never decrement) the netname if the last character is a number. So
you can simply add the rest of the nets by clicking on the wires.
Lets connect the CLK lines of the two devices together using wires. Extend one wire out to add a
net called CLK.
We need a source for power and ground so lets add a MIL-STD (Machine Intelligence Lab
Standard) power connector. It is a four pin header with power-NC-GND-NC. You cannot do
damage if you connect this backwards. The four pin header we will use is in the D_DEVICE
library. It is called “4 PIN.” You will notice that the part has a designator “U?”. We want it to be
“CON?”. Double-click on the part and change that problem.
Using the special symbols tool, add two symbols (it doesn’t matter how they look but make one
upside down by pressing the space-bar twice.) Double click on the first one and change the net
name to “VCC” and the style to “Arrow.” Double click on the second one and make the net name
“GND” and the style “Power Ground.” You will now have power and ground. Connect those
symbols (VCC and GND) to the first and third pins of the connector, respectively.
I want to ground all of the parallel inputs to the counter devices and ground some of the control
signals so add another special symbol and make it a ground. Connect it to the parallel loads with
wires. Connect TC of the lowest significant nibble to the CET (count-enable trickle) of the MSN.
Follow my diagram in connecting grounds and VCCs to the various signals. NOTE: It is generally
not advisable to connect VCC (power) directly to an input. In this case, I don’t care but if you did,
place a resistor in line.
We need a connector to get the clock in and signals out. So add a CON9 part from the DEVICE
library. Once again, change “J?” to “CON?.” On the first pin, extend the pin with a wire and give
it a net called CLK. Extend the rest of the pins, add bus entries, a bus wire, a port (called D[0..8])
and finally all of the nets.
The circuit is almost finished. There are a couple of final steps:
1)
Back-annotate the part names. Under Tools/Annotate click Re-Annotate all parts
and click OK. By doing this you change all question marks to numbers. Now
you will have U1, U2, CON1, CON2.
2)
Run an Electric Rule Check (ERC.) This is located under Tools/ERC. The ERC
checks for problems such as power on inputs (as mentioned before, this is not
recommended), multiple net names for the same net and more. (FYI: Protel only
“knows” inputs from outputs by the signal description entered by the person
who created the part. If the person was lazy, they may have made the pins
“passive” and Protel will assume that they are anything: input, output, power or
whatever. The moral is: always give the pins signal descriptions when you make
a part – it will help you in the long run.)
3)
Give the parts footprints. This is so that you can make a PCB out of it. The way
you do this is by double clicking on the part and entering a footprint name. Use
the footprint sheets to determine what footprints you need.
4)
Create a netlist. This is under Tools/Create Netlist. The netlist is how you
convert the schematic to a PCB. More on that later…
You are now done with schematic.
NOTES:
You might be wondering how the chips get power. Well, if you double click on a chip
part, select Hidden Pins. Suddenly two wires will show. You cannot connect wires or
nets to them because they already have nets attached – created when the part was made.
In this (and most) instances this is VCC for power and GND for ground.
1
2
3
4
5
6
VCC
CON1
1
2
3
4
D
D
D[0..8]
4PIN
CON2
CLK
U1
3
4
5
6
VCC
CLK
7
10
2
9
1
P0
P1
P2
P3
Q0
Q1
Q2
Q3
TC
14
13
12
11
15
D4
D5
D6
D7
CEP
CET
CLK
PE
MR
1
2
3
4
5
6
7
8
9
CON9
D[0..8]
74HC163
U2
3
4
5
6
7
10
2
9
1
C
P0
P1
P2
P3
Q0
Q1
Q2
Q3
TC
14
13
12
11
15
D0
D1
D2
D3
CEP
CET
CLK
PE
MR
C
74HC163
B
B
A
A
Title
Size
Number
Revision
B
Date:
File:
1
2
3
4
5
18-Feb-1999
Sheet of
F:\POMALLEY\TUTORIAL\TUT1.SCH Drawn By:
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