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:: Research Group Embedded Interaction :: Media Informatics :: Ludwig-Maximilians-University Munich

Printed Circuit Board Layout How-To

Please see also our other how-to pages:

In this How-To we will address the design of printed circuit boards with Eagle from Cadsoft.

First, make a new schematic.

Eagle - Create a new project

Give your new project a cool name.

Eagle - label a newly created project

Add a new schematic to your project.

Eagle - add a new schematic

You now will be presented with the schematic editor. In the picture below, the "ADD" button is already highlighted.

Eagle - add electrical parts to a new schematic

After you clicked on the ADD button, you will be presented a search dialog (see below). In the example, I searched the part MA03-1. Click ok and position it somewhere on the free space of the schematic editor. After you left-click it to the pane, press Escape to get back to the ADD dialog. Repeat this step until you have selected and positioned all electronic parts that you need. Click OK or Cancel and leave the ADD dialog. If you just added a part, pressing Escape twice leaves the add mode.

If the parts of your layout are not in the library, check Cadsoft's library download page. If you are lucky, you will get the parts there. If not, you will have to build the packaging and housing and the wiring part of the element yourself. This is at the moment out of the scope of this tutorial.

Eagle - search electrical parts and add them to a schematic

Now that you have added all necessary electrical parts to your schematic, you are ready to hopefully correctly connect the parts together. It is by the way a good time to save your work - if you did not do that yet.

Before we start connecting pins, we first add the pins of the parts to the items that are currently displayed on the editor. To select the layers for display, click on the display icon (see left picture below) and additionally select the layer 93, 'Pins'. Confirm by clicking on ok.

Now you should see green pins near your electrical parts. You can only connect the electrical net to this pins.

Eagle - select layers for display                   Eagle - select pin layer for display for connecting electrical wires

Click on the "NET" icon (see the following picture).

Eagle - add electrical net (wires) to a schematic

Now you can draw electrical lines from one part to another. Left-click to start drawing a wire. To stop drawing a wire, click left twice. In the example below, I connected two parts. I started by left-clicking in the green circle of the pin 3 of the part labeled "SV1". I then moved the cursor to the pin 2 of part "JP1". I clicked left again to stop drawing lines. If you draw edges (or any other intermediate points) click left to fix that point. Stop making points by double-left-clicking.

Eagle - a simple example of how to connected electrical parts with wires

After connecting all parts in the schematic editor, it is now time to check if all electrical rules and requirements are met (if you e.g. forget to connect pins or if you did not add a GND). For the electrical rule check, click on the icon labeled 'Erc'. If everything is ok, in the status bar the text 'ERC: 0 errors, 0 warnings' is displayed. Otherwise a window containing a text with the errors is displayed.

Eagle - electrical rule check

Now that there are no errors left, click on the 'Board' icon.

Eagle - Switch from schematic to board or from board to schematic

When you click on the 'Board' icon for the first time, you will be asked if the board shall be created from the schematic. Answer 'Yes'.

Eagle - create board from schematic

Initially, all parts are placed outside the printed circuit board. You have to move the parts to the position on the board where they are supposed to be.

Eagle - a simple board example

To simplify positioning, turn the grid on. Click on the 'Grid' icon. Configure the grid to your needs, e.g. select the unit of measure and the grid size itself. We are often using half an inch (=1.27mm) as grid. Make sure to select the radio button 'On' in the 'Display' section (top left) which is initially 'Off'. If you like a grid consisting of lines or only dots at the intersections is up to you ('Style' section in the top right of the dialog.)

Eagle - add a grid       Eagle - configure the grid for better positioning of the electrical parts

By left-clicking on an object, you select it. If too many objects are too close together, one gets chosen and you can swap through by right-clicking through the list. You always have to look at the text in the status bar.

You can turn any selected object by right-clicking.

You can select a group on parts by clicking on the 'Group' icon. Select the group of parts you want to move. Click now on the 'Move' icon. Click right on the highlighted group of selected parts. If you click right twice you can turn the group. Move it to where you like it and then left-click to drop the grouped parts there.

Eagle - Group Tool for grouping electrical parts        Eagle - Move tool for moving part or groups of electrical parts

You now have laid out the board. Take a second to verify that all components have enough space around them for e.g. cooling or connecting pins. The Elektor-article (see end of page) tells you some things you should additionally consider.

Now you are ready to make Eagle calculate the electrical wiring. Click on the 'Auto' icon and confirm the now open dialog with 'OK'.

Eagle - auto route tool for automatic wire generation     Eagle - auto router dialog

If everything worked out (that is, if you connected all pins and the ERC check showed no errors), the layout is ready. If you like - or if necessary - you can now move some wires by first deleting them and re-adding them. For this, first select the ripup tool (see picture below) to remove (ripup) the wires from the printed circuit board. Now select the route tool (see below) to re-add it.

Eagle - ripup tool       Eagle - route tool

Links

Links - Programs for Printed Circuit Board Layout

Literature References