Introduction

This tutorial leads you through the steps necessary to make a simple two-sided PCB using EAGLE. This guide is operational: it shows in detail what you do and how to do it. Before you start the tutorial take 5 minutes to go through the Cadsoft EAGLE Guided tour, to get an overview. It will pay you to work through all of this guide, following the steps yourself, before attempting your first unguided PCB.

A short note about the EAGLE on-line help documentation. This is pretty good but based on the command-line interface to EAGLE. It is easier when learning to use the drag-and-drop GUI, which we follow in this tutorial.

This guide assumes that you are designing a two-sided PCB with plated-through holes (PTH), the normal case, and supported by the freeware version of EAGLE providing your board is no larger than 100mmX80mm. If you want to download the freeware EAGLE to your own PC this is easy. Look for the latest freeware version for your operating system & language (e.g. eagle-win-5.2.exe for windows XP and English). 

EAGLE can also be used to design multi-layer and single-sided PCBs, non-PTH PCBs, etc. It can also be easily adapted to produce boards with coarser features, suitable for low quality optical processes and manual manufacture. See the EAGLE Configuration Guide for more details of use with different technologies after you have followed this guide. In order to design a PCB, you need to complete the following steps:

1. Create a schematic sheet & add components
2. Add nets to the schematic (connect components)
3. Check schematic (Electrical Rule Check or ERC)
4. Create a board outline
5. Position components on the board
6. Route tracks between the components
7. Check board (Design Rule Check or DRC)
8. Pour copper to fill empty spaces on the board
9. Perform Final Checks

This tutorial leads you through the steps necessary to make a simple two-sided PCB using EAGLE. This guide is operational: it shows in detail what you do and how to do it. Before you start the tutorial take 5 minutes to go through the Cadsoft EAGLE Guided tour, to get an overview. It will pay you to work through all of this guide, following the steps yourself, before attempting your first unguided PCB.

A short note about the EAGLE on-line help documentation. This is pretty good but based on the command-line interface to EAGLE. It is easier when learning to use the drag-and-drop GUI, which we follow in this tutorial.

This guide assumes that you are designing a two-sided PCB with plated-through holes (PTH), the normal case, and supported by the freeware version of EAGLE providing your board is no larger than 100mmX80mm. If you want to download the freeware EAGLE to your own PC this is easy. Look for the latest freeware version for your operating system & language (e.g. eagle-win-5.2.exe for windows XP and English). 

EAGLE can also be used to design multi-layer and single-sided PCBs, non-PTH PCBs, etc. It can also be easily adapted to produce boards with coarser features, suitable for low quality optical processes and manual manufacture. See the EAGLE Configuration Guide for more details of use with different technologies after you have followed this guide. In order to design a PCB, you need to complete the following steps:

1. Create a schematic sheet & add components
2. Add nets to the schematic (connect components)
3. Check schematic (Electrical Rule Check or ERC)
4. Create a board outline
5. Position components on the board
6. Route tracks between the components
7. Check board (Design Rule Check or DRC)
8. Pour copper to fill empty spaces on the board
9. Perform Final Checks

Step 1: Schematic Creation

File->New->Project.
Rename the project if you wish as follows: the control panel window indicates whether a project is open with a green circle next to the project name. Click this if necessary to close theproject. Then
Right-click->Rename
on the project’s name. After having renamed the project you can reopen it.Right-click on the 

Project name ->New->Schematic. The schematic window will open. Inside the schematic window:
File->Save as (choose a suitable name for your schematic sheet. NB – the freeware version of EAGLE allows only one sheet per design). For the first half of this tutorial you will be working with the schematic window, and can minimise the control panel window.

                              

Add components to your schematic

Edit->Add-> Select component.

Each open library in the ADD window contains a list of components (click + if not visible).Some components have multiple packages (click on + to select the correct package). The component schematic symbol and package layout appear in the two windows to the right of the library window. Each component has a description you can check to see what it is. When you have identified the correct component and package (component & package will be visible in the two windows) click OK to start the ADD procedure (NB DONT click Drop in this box,

if you do this you will lose the current component and need to re-open the library with USE to retrieve it). The ADD window will vanish and a schematic outline will track the cursor when it is over the main schematic sheet window. Left-click to place each component. Right-click before placing to rotate the component. Any number of the selected component can be added.

To stop the ADD procedure select Edit->Stop Command.

File->New->Project.
Rename the project if you wish as follows: the control panel window indicates whether a project is open with a green circle next to the project name. Click this if necessary to close theproject. Then
Right-click->Rename
on the project’s name. After having renamed the project you can reopen it.Right-click on the 

Project name ->New->Schematic. The schematic window will open. Inside the schematic window:
File->Save as (choose a suitable name for your schematic sheet. NB – the freeware version of EAGLE allows only one sheet per design). For the first half of this tutorial you will be working with the schematic window, and can minimise the control panel window.

                              

Add components to your schematic

Edit->Add-> Select component.

Each open library in the ADD window contains a list of components (click + if not visible).Some components have multiple packages (click on + to select the correct package). The component schematic symbol and package layout appear in the two windows to the right of the library window. Each component has a description you can check to see what it is. When you have identified the correct component and package (component & package will be visible in the two windows) click OK to start the ADD procedure (NB DONT click Drop in this box,

if you do this you will lose the current component and need to re-open the library with USE to retrieve it). The ADD window will vanish and a schematic outline will track the cursor when it is over the main schematic sheet window. Left-click to place each component. Right-click before placing to rotate the component. Any number of the selected component can be added.

To stop the ADD procedure select Edit->Stop Command.

Step 2: Add nets to schematic

Use the Draw->Net command to connect components. DO NOT use Draw->Wire.
Draw->Net Left-mouse click on end of source pin or wire, left-mouse click when a change of direction in
the wire is required, left-mouse click on the destination. A connection will be made and highlighted green with connected wires indicated by a bobble. Note that single right-anglebends will be made automatically, and that right-mouse click during the net command willcycle between different possible wire directions.

EAGLE has an excellent unlimited UNDO facility (Edit->Undo). Use this when nets go wrong. If they go very wrong use Edit->Delete (followed by right-clicks on unwanted objects) to remove unwanted nets and start again.

Step 2a Add supply connectors to the schematic –

Supply connectors are a special type of component which does not exist physically on the PCB. You can use them to make the schematic neater by naming supplies, and using

connectors instead of nets to join together supply connections which are not adjacent. All supply connectors with the same name connect together. Some useful connectors can be found in the ee2parts library. Supply connectors have one more very clever use. Some ICs have supply pins which do not show on the schematic symbol. These will be automatically connected to a net with the correct supply connector (which has the same name as the pin). If you do not have a supply connector with the correct name it will result in an ERC error (see
next step). Obviously it is an error not to connect the supply pins for op-amps that you use. Sometimes you will want to connect together distant subnets which are NOT a supply. You can’t use a supply connector for this since op-amp outputs joined to supply connectors is an error. Choose a suitable alphanumeric name (e.g. sigout). Use Edit->Name and left-click on each of the nets to be connected – giving them the same name will connect them together. IMPORTANT: to make this connection visible on the schematic use Draw->Label to add a label (which will display the net name) to each subnet so joined. Try labelling the op-amp inverting output “OUT” to see how this works and then undo the operations (Edit->Undo or Ctrl-Z will work through any number of commands).

Step 2b add I/O pads and testpoints to the layout –

To get signals on and off the PCB you need either connector components or connecting wires. The best way to join wires to a prototype PCB is via terminal pads which have circuit pins soldered – wires can then be soldered to the pins. Add the PAD-TERMINAL component from the EEE library to allow wires for the V+, V- and GND supplies. Throughout your circuit you will have internal nets which you need to measure when testing. Add testpoints (PAD- TESTPOINT component) to these nets. Testpoints will appear on the schematic as small pads similar to terminal pads – you do not however need to solder circuit pins onto testpoints.

Use the Draw->Net command to connect components. DO NOT use Draw->Wire.
Draw->Net Left-mouse click on end of source pin or wire, left-mouse click when a change of direction in
the wire is required, left-mouse click on the destination. A connection will be made and highlighted green with connected wires indicated by a bobble. Note that single right-anglebends will be made automatically, and that right-mouse click during the net command willcycle between different possible wire directions.

EAGLE has an excellent unlimited UNDO facility (Edit->Undo). Use this when nets go wrong. If they go very wrong use Edit->Delete (followed by right-clicks on unwanted objects) to remove unwanted nets and start again.

Step 2a Add supply connectors to the schematic –

Supply connectors are a special type of component which does not exist physically on the PCB. You can use them to make the schematic neater by naming supplies, and using

connectors instead of nets to join together supply connections which are not adjacent. All supply connectors with the same name connect together. Some useful connectors can be found in the ee2parts library. Supply connectors have one more very clever use. Some ICs have supply pins which do not show on the schematic symbol. These will be automatically connected to a net with the correct supply connector (which has the same name as the pin). If you do not have a supply connector with the correct name it will result in an ERC error (see
next step). Obviously it is an error not to connect the supply pins for op-amps that you use. Sometimes you will want to connect together distant subnets which are NOT a supply. You can’t use a supply connector for this since op-amp outputs joined to supply connectors is an error. Choose a suitable alphanumeric name (e.g. sigout). Use Edit->Name and left-click on each of the nets to be connected – giving them the same name will connect them together. IMPORTANT: to make this connection visible on the schematic use Draw->Label to add a label (which will display the net name) to each subnet so joined. Try labelling the op-amp inverting output “OUT” to see how this works and then undo the operations (Edit->Undo or Ctrl-Z will work through any number of commands).

Step 2b add I/O pads and testpoints to the layout –

To get signals on and off the PCB you need either connector components or connecting wires. The best way to join wires to a prototype PCB is via terminal pads which have circuit pins soldered – wires can then be soldered to the pins. Add the PAD-TERMINAL component from the EEE library to allow wires for the V+, V- and GND supplies. Throughout your circuit you will have internal nets which you need to measure when testing. Add testpoints (PAD- TESTPOINT component) to these nets. Testpoints will appear on the schematic as small pads similar to terminal pads – you do not however need to solder circuit pins onto testpoints.

Step 3: Electrical Rule Check

When you think you have connected everything you must do an ERC which will identify
disconnected pins, nets which are next to each other but not connected, etc.
Tools->ERC

The error messages indicate what is wrong. The error check is quite intelligent and knows about power supplies, inputs, outputs, etc. Click on a message to highlight the corresponding error on the schematic.

ERC messages indicate either errors – must be mended – or warnings – will not stop board layout but nevertheless indicate a problem. You should normally eliminate all warnings. One common source of ERC error is when wires which you want to connect look as though they connect are in fact not joined. Where a wire joins the middle of another there must be a green circle (Draw->Junction) to indicate connection. Sometimes two nets are adjacent and appear joined but in fact are not. The View->Show tool ( ) is invaluable here. If you click on any part of a net it will highlight all connected wires and component endpoints. You can then easily check what is missing. When you encounter such an error simply delete (Edit->Delete) line segments around the problem and rewire again (Draw->Net).

 

When you think you have connected everything you must do an ERC which will identify
disconnected pins, nets which are next to each other but not connected, etc.
Tools->ERC

The error messages indicate what is wrong. The error check is quite intelligent and knows about power supplies, inputs, outputs, etc. Click on a message to highlight the corresponding error on the schematic.

ERC messages indicate either errors – must be mended – or warnings – will not stop board layout but nevertheless indicate a problem. You should normally eliminate all warnings. One common source of ERC error is when wires which you want to connect look as though they connect are in fact not joined. Where a wire joins the middle of another there must be a green circle (Draw->Junction) to indicate connection. Sometimes two nets are adjacent and appear joined but in fact are not. The View->Show tool ( ) is invaluable here. If you click on any part of a net it will highlight all connected wires and component endpoints. You can then easily check what is missing. When you encounter such an error simply delete (Edit->Delete) line segments around the problem and rewire again (Draw->Net).

Step 4: Create the board

Open the schematic created previously, which should now be correct and pass its ERC check(see Step 3 above for warnings which can be ignored – all other warnings and errors must be corrected).

File->Switch to Board

Since the schematic does not yet have a board attached you will be asked whether you want to create one from the schematic: say yes. The board consists of all your components, with connections shown as a rats-nest, and a rectangular wire outline (default 100mmX80mm) which represents the board area.

Change the user interface so that the board background is displayed in white or light yellow:

Option->User interface->layout->tick white or coloured

Open the schematic created previously, which should now be correct and pass its ERC check(see Step 3 above for warnings which can be ignored – all other warnings and errors must be corrected).

File->Switch to Board

Since the schematic does not yet have a board attached you will be asked whether you want to create one from the schematic: say yes. The board consists of all your components, with connections shown as a rats-nest, and a rectangular wire outline (default 100mmX80mm) which represents the board area.

Change the user interface so that the board background is displayed in white or light yellow:

Option->User interface->layout->tick white or coloured

Step 5: Position the components inside the board outline

Move the components one by one inside the rectangular board outline (Edit->Move) and position them where you want. Note that you must move components into the allowed 100*80mm area and cannot rearrange them outside the allowed area – this is a restriction imposed by freeware EAGLE. It is a good idea first to print out the schematic so you know what is connected to what and can easily position components in a logical order. Do not worry if you get things wrong, you can reposition at a later stage. Note that you can also rotate
components (Edit->Rotate). NB – you are allowed to flip/mirror PCB components. DONT DO
THIS – it will require the component to be mounted on the wrong side of the board!

Move the components one by one inside the rectangular board outline (Edit->Move) and position them where you want. Note that you must move components into the allowed 100*80mm area and cannot rearrange them outside the allowed area – this is a restriction imposed by freeware EAGLE. It is a good idea first to print out the schematic so you know what is connected to what and can easily position components in a logical order. Do not worry if you get things wrong, you can reposition at a later stage. Note that you can also rotate
components (Edit->Rotate). NB – you are allowed to flip/mirror PCB components. DONT DO
THIS – it will require the component to be mounted on the wrong side of the board!

Step 6: Route the tracks

This has many options, but the EEE defaults (which you loaded via ee_autoroute.ctl) normally work fine so click OK. The rats-nest connections will be changed into routed PCB tracks as in Figure 7b. You know the routing is complete because of the message in the bottom edge of the window. Anything less than 100% indicates some connections not routed.

This has many options, but the EEE defaults (which you loaded via ee_autoroute.ctl) normally work fine so click OK. The rats-nest connections will be changed into routed PCB tracks as in Figure 7b. You know the routing is complete because of the message in the bottom edge of the window. Anything less than 100% indicates some connections not routed.

Step 7: Design Rule Check

Tools->DRC

This command will bring up a window showing the currently loaded set of design rules – for the EE2 design project this should be ee_rules_dp latest version, which you loaded in step 4. To change to a new set of rules (in a .dru file), click Load, select the new file, click Open, to view the new rules, then click Apply to use them with the board.
Click Check and this will run the design rules and say whether there are any errors. If there are errors 

Tools->Errors will display them. You must correct all DRU errors.

Tools->DRC

This command will bring up a window showing the currently loaded set of design rules – for the EE2 design project this should be ee_rules_dp latest version, which you loaded in step 4. To change to a new set of rules (in a .dru file), click Load, select the new file, click Open, to view the new rules, then click Apply to use them with the board.
Click Check and this will run the design rules and say whether there are any errors. If there are errors 

Tools->Errors will display them. You must correct all DRU errors.

Step 8: Pour Copper

PCBs should normally have all area not used for tracks covered with copper “ground plane” to reduce high-frequency noise. This does not interfere with the normal tracks, in fact it can be used to reduce the tracks required. Normally, all “poured copper” is connected to a single circuit supply connector. EAGLE is clever  enough to route connections on this supply using the poured copper, thus reducing the number of tracks.

An added bonus is that the poured copper connections are much lower impedance than is possible using tracks. We will first add poured copper to the tutorial board in the simplest possible way. We use oneside only and connect the poured copper to the power supply connector GND.

EAGLE uses polygons drawn on top or bottom of the board to mark the boundary of an area within which copper will be automatically poured.

To draw a polygon for the V- supply type “Polygon GND” in board wndow command box

PCBs should normally have all area not used for tracks covered with copper “ground plane” to reduce high-frequency noise. This does not interfere with the normal tracks, in fact it can be used to reduce the tracks required. Normally, all “poured copper” is connected to a single circuit supply connector. EAGLE is clever  enough to route connections on this supply using the poured copper, thus reducing the number of tracks.

An added bonus is that the poured copper connections are much lower impedance than is possible using tracks. We will first add poured copper to the tutorial board in the simplest possible way. We use oneside only and connect the poured copper to the power supply connector GND.

EAGLE uses polygons drawn on top or bottom of the board to mark the boundary of an area within which copper will be automatically poured.

To draw a polygon for the V- supply type “Polygon GND” in board wndow command box

Step 9 Final Checks before Manufacture

YOU MUST check these before submitting your final brd and sch files.

 Check current board layout is saved
 Check no ERC warnings or errors (except lack of value for R,C and supply nets with wrong name – and these must be checked on schematic).
 Check DRC rules loaded are correct for manufacturer (eerules_dp.dru v3.40 2008).
 Check board size is rectangular and has precisely the specified X,Y dimensions using run->statistic_brd. Boards with incorrect dimensions will be rejected
 Check auto command gives 100% routing without polygons falling apart (message at bottom of window after auto command)
 Check there are no DRC errors
 Check component names (layer 25) are all visible, on board, not overlapping pads, and if possible not hidden under components. Note that component values (layer 27) are not printed on silk screen. (Board will be OK if you do not do this but less easy to build)
 Check that no object (track or pad) lies within 2mm of the board edge
 Check you have included, easily visible, a layer 21 caption giving your lab group Your .brd file now contains all the information necessary to manufacture the PCB, however make sure you keep safe both this and the schematic – you will be able to print schematics, layouts, component value lists etc for use in debugging.\

To know more….. 

Copyright©Tom Clarke

YOU MUST check these before submitting your final brd and sch files.

 Check current board layout is saved
 Check no ERC warnings or errors (except lack of value for R,C and supply nets with wrong name – and these must be checked on schematic).
 Check DRC rules loaded are correct for manufacturer (eerules_dp.dru v3.40 2008).
 Check board size is rectangular and has precisely the specified X,Y dimensions using run->statistic_brd. Boards with incorrect dimensions will be rejected
 Check auto command gives 100% routing without polygons falling apart (message at bottom of window after auto command)
 Check there are no DRC errors
 Check component names (layer 25) are all visible, on board, not overlapping pads, and if possible not hidden under components. Note that component values (layer 27) are not printed on silk screen. (Board will be OK if you do not do this but less easy to build)
 Check that no object (track or pad) lies within 2mm of the board edge
 Check you have included, easily visible, a layer 21 caption giving your lab group Your .brd file now contains all the information necessary to manufacture the PCB, however make sure you keep safe both this and the schematic – you will be able to print schematics, layouts, component value lists etc for use in debugging.

To know more….. 

Copyright©Tom Clarke

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