View source for Tutorial: Printed-Circuit Boards

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<font size="+2">Page under construction!</font>
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--[[User:Thiebaut|D. Thiebaut]] 12:37, 20 June 2011 (EDT)
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=Software=

All are open-source.

* [http://sourceforge.net/projects/tinycad/ TinyCAD]
* [http://www.freepcb.com/downloads.htm FreePCB]
* [http://www.pentalogix.com/index.php?option=com_content&view=article&id=50&Itemid=55 ViewMate] (get the free registration code via email to install)
* [http://www.pcbexpress.com/ PCBExpress/Sunstone]: Web site where to order PCB from.


=Process=

* First create schematics with TinyCAD
* Then route the lines on a 4-layer board with FreePCB
* Check the CAM files generated by FreePCB with ViewMate
* Once the output files are ready, upload them to PCBExpress (accept 4-layers+mask option).

=An Example=
* We'll create a PCB for the following simple circuit taken from [http://www.seekic.com/forum/22_circuit_diagram/14875_SIMPLE_TTL_CRYSTAL_OSCILLATOR.html seekic.com]:
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[[Image:7404Oscillator.jpg|500px]]
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==TinyCAD==
===Generating the Schematics===
* Open TinyCAD
* Open the 74TTL library in the left pane
* Pick the Hex Inverters
* Drop two inverters on the blank schematics pane
* Update the reference for each gate (U1A and U1B) in the '''Tool Options''' window.
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[[Image:TinyCAD1.png|500px]]
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* Open the '''Analog''' library, and pick the '''Resistor''', and drop it on the schematics pane where resistors are needed.  Use the '''Tool Options''' window to set the orientation of the resistors to '''left'''.
* For each resistor, use the '''Tool Option''' menu to set the '''Ref''' to R''n'' where ''n'' is 1, 2, 3, or 4, and '''Add''' a '''value''' field to the''' Parameter''' list for indicating the value in ohm.
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[[Image:TinyCAD2.png|500px]]
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* To add the crystal, search for it in the '''Filter''' box and pick the '''X-Crystal''' symbol.
* It might be a good time to save your work!

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[[Image:TinyCad3.png|500px]]
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* Click on the '''Wire''' tool button and use the mouse to connect all the component pins together, recreating the wiring of the original circuit.
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[[Image:TinyCad4.png|500px]]
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* Add out output connector ('''J0 - Connection Output''')
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[[Image:TinyCad5.png|300px]]
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===Assigning Packages to Parts===
* Depending on the type of circuits you will be using, you can now edit your different parts and add a new '''Package''' field, as illustrated here for the 7404 chip.
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[[Image:TinyCad7.png|500px]]
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* Refer to the FreePCB documentation for the type of packages supported.  Here's the list of packages picked for this project:
<code><pre>
U1   14DIP300
Rn   RC06
X1   CK12-B
J0   HOLE_100_SQR_200
</pre></code>
:(where ''n'' in R''n'' is 1, 2, 3, and 4.)
* Assigning packages to the parts now will allow the FreePCB, our next software tool to automatically generate footprints for our parts.

===Testing===
* Check your design by clicking on '''Special''' in the top menu, then '''Check Design Rules'''.  
* Accept the defaults and click '''Check'''
* You should get a message indicating that Vcc and GND of the 7404 are not connected.
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[[Image:TinyCad6.png|500px]]
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===Generate the Net-List File===
* Using the top menu, click '''Special''', '''Create PCB Net List''', select '''PADS-PCB''' for the format, and save to file.
* You should get the following output:

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[[Image:TinyCAD8.png|500px]]
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* You are now ready for the second step

==FreePCB==
* The official manual for FreePCB is a ''Must-Read'' and can be found [http://www.freepcb.com/freepcb_user_guide.pdf here].
* Open '''FreePCB'''
* From the menu, '''File''', '''New''', and create a new project
** Name: '''oscillator'''
** Layers: '''2''' (sufficient for right now)
** accept all the other default value
* Click '''Ok'''
* You should be presented with an empty grid:

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[[Image:FreePCB1.png|500px]]
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===Board Outline===
* Create the outline of your board.  This can be any polygone shape you can define by consecutive points.
* From the top menu, click '''Add''', '''Board Outline''', then click points on the grid to create a rectangle.  Don't worry about the size yet, all the points can be moved in or out later to create as tight a layout as you wish.
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[[Image:FreePCB2.png|500px]]
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* Make sure your last point coincide with your first point.
===Import the Net List file===
* From the main menu, browse around your file system and pick the '''oscillator.net''' file created by ''TinyCAD'' in the steps above.
* FreePCB should show the parts and rat wires connecting the different parts of your circuit:
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[[Image:FreePCB3.png|500px]]
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[[Category:PCB]][[Category:CSC270]][[Category:TinyCAD]][[Category:FreePCB]][[Category:ViewMate]][[Category:PCBExpress]]